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Glossary of WJ Products

A

ACI	Adjacent Channel Interface. ACI is interference caused by extraneous power from a signal in an adjacent channel.
ACPR	Adjacent Channel Power Ratio. The ratio of unwanted power in the adjacent channel relative to the wanted channel power.
Active Bias	A circuit that employs feedback to maintain bias level. Often a constant current circuit is used.
Active Tag	An RFID tag that has a transmitter to send back information rather than reflecting back a signal from the reader like passive tags do. Most active tags use batteries as a partial or complete source of power to transmit a signal back tot he reader. Active tags can be read from long distances, but they're much more expensive than passive tags. They're mostly used for tracking expensive items over long ranges.
ADC	Analogue to Digital Converter. An electronic circuit that converts an analogue signal into a binary number. The reverse operation is formed by a DAC.
AFC	Automatic Frequency Control. A device or circuit that maintains the frequency of an oscillator within the specified limits with respect to a reference frequency.
AGC	Automatic Gain Control. A device or circuit that maintains the gain of a circuit or amplifier by comparing it with a known reference.
AGC Threshold	The level of input current at which the AGC circuit becomes active.
AGC Time Constant	The amount of time it takes to achieve the required AGC level; also, the amount of time it takes to recover from AGC.
Air Interface Protocol	The rules that govern how RFID tags and RFID readers communicate.
AM	Amplitude Modulation. A form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal.
Ampere (A)	A unit of electric current equal to one coulomb (C) of charge per second.
Amplitude	The maximum absolute value of a periodic curve measured along its vertical axis (the height of a wave, in layman's terms).
AMPS	Advanced Mobile Phone System. An analog mobile phone system standard introduced in the Americas in 1984.
Antenna	A structure that is intended to radiate electromagnetic waves into or collect electromagnetic energy from space.
ASIC	Application Specific Integration Circuit. An integrated circuit (IC) customized for a particular use, rather than intended for general-purpose use.
ASSP	Application Specific Standard Product. An integrated circuit that implements a specific function that appeals to a wide market, as opposed to ASICs that are designed for one customer.
Attenuation	The degree to which an input signal is reduced in amplitude at the output of a circuit or device. Measured in dB.
Auto-ID Center	A non-profit collaboration between private companies and academia that pioneered the development of an Internet-like infrastructure for tracking goods globally through the use of RFID tags.
Automatic Identification	A broad term that covers methods of collecting data and entering it directly into computer systems without human involvement. Technologies normally considered part of auto-ID include bar codes, biometrics, RFID and voice recognition.

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B

Balanced Mixer	A type of mixer that forms from two signals.
Balun	A transformer circuit that couples a balanced transmission line to an unbalanced transmission line.
Bandwidth (BW)	The range (or band) of frequencies occupied by a system. Measured in Hertz (Hz).
Back Scatter	A standard method of identifying the manufacturer and product category of a particular item.
Bias Point	The dc voltage which allows the circuit to operate with a certain characteristic. Also known as quiescent point or operating point.
BiCMOS	Bipolar Complementary Metal Oxide Semiconductor. Refers to the integration of bipolar junction transistors and CMOS technology into a single device.
Bipolar Junction Transistor (BJT)	A type of transistor so named because the main conduction channel employs both electrons and holes to carry the main electric current.
Bluetooth	Bluetooth is a short range radio standard operating at a frequency of 2.45GHz, primarily designed for low power consumption and low data rate (2.1Mbit/s) applications. Bluetooth creates a wireless personal area network (PAN) and is used to exchange information between devices like personal digital assistants (PDAs) and mobile phones.
BTS	Base Transceiver Station. The BTS contains the equipment for transmitting and receiving of radio signals at a fixed location to create a cell site for mobile communications.

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C

Cascade	A tandem arrangement of two or more components in which the output of one component is connected to the input of the next component.
CATV	Community Antenna Television (or cable television). A system of providing television and radio services to consumers directly to people's televisions through fixed optical fibers or coaxial cables.
CDMA	Code Division Multiple Access. A digital transmission technique based on direct sequence spread spectrum.
CDMA2000	Code Division Multiple Access 2000. A third generation (3G)wireless system, CDMA2000 is a trademark of Qualcomm, the company that commercialized CDMA.
Cellular	A wireless phone system that uses a grid of cells, each managed by a base station. Often refers to such systems that operate in our around the 800 - 1000 MHz band.
Celsius (°C)	The degree Celsius (°C) is a common unit of temperature. It can be converted to Kelvin (K) using K = °C+273.15.
Channel	A path of communication, either electrical or electromagnetic, between two or more points.
Channel 1	The first allocated broadcast TV frequencies in the United States. In 1945 the FCC decided to move the existing stations to higher frequencies and reallocate the Channel 1 band, 44 to 50 MHz for fixed and mobile services.
Chip	An integrated circuit. The physical structure upon which integrated circuits are fabricated as components of telephone systems, computers, memory systems, etc. Typically a chip refers an integrated circuit has been "packaged" in insulating plastic.
Circuit	A circuit is a network of circuit elements such as resistors, inductors, capacitors, semiconductors, etc. that performs a specific function.
Circuit Board	A circuit board is used to mechanically support and electrically connect components using conductive tracks etched from copper sheets laminated onto a non-conductive substrate. Also known as Printed Circuit Board (PCB).
CMOS	Complementary Metal Oxide Semiconductor. A class of semiconductor which consumes very little power by using both NMOS and PMOS transistors.
Component	A device or physical element in an electronic system that performs an electrical or electronic function.
Compression	Reducing the bandwidth or number of bits needed to encode information or encode a signal, typically by eliminating likng strings of identical bits or bits that do not change in successive sampling intervals.
Continuous Wave (CW)	An electromagnetic wave which has constant amplitude and frequency. A CW signal is also given the name carrier wave in telecommunications, which is modulated to carry information.
Conversion Loss	The reduction of signal power as a result of freqeuncy conversion from RF to IF or vice versa. Measured in dB.
COTS	Commercial off the Shelf. A ready made and available item for sale often used to offset internal development costs.
Cyclic Redundancy Check (CRC)	A method of checking data stored on an RFID tag to be sure that it hasn't been corrupted or some of it lost.

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D

DAC	Digital Analogue Converter. An electronic component for converting digital information into an analogue signal. An Analog to Digital converter (ADC) performs the reverse operation.
dB	Decibel is one tenth of a Bel (B) and is a measure of ratio between two quantities. The ratio of two power levels in dB is PdB=10log(P1/P2).
dBm	dBm is a measure of power and is defined as the ration in dB relative to 1mW e.g. 1mW = 0dBm adn 1W = 30dBm.
DBS	Direct Broadcast Satellite. A term used to refer to satellite television broadcasts intended for home reception.
DC	Direct Current. The flow of electric charge in one direction within an electrical conductor.
DCS	Digital Communications System.
Die	The semiconductor block on which circuits have been etched to create an IC. The die is formed when the wafer is cut into small rectangles.
Diode	A device that conducts electricity in one direction only.
Diplexer	A filter circuit with two inputs and one output. This component is used to combine two different frequency bands such as in a transmitter.
Discrete	Before the invention of the IC, electronic circuits were constructed from discrete components which are separate electronic components such as diodes and transistors.
Dissipation	The transfer of energy from one body to another as a result of a difference in temperature or conversion of electrical energy to heat energy.
Double Balanced Mixer	A frequency translation circuit which consists of four components with nonlinear impedance, typically Schottky diodes or FETs, connected in a ring quad configuration, with balun transformers at the RF and LO inputs to connect unbalanced transmission lines to the balanced quad. This mixer provides superior suppression of the LO and RF signals in the output leaving only the sum and difference frequencies.
Downconverter	A device for lowering the frequency of a modulated radio-frequency carrier.
DSP	Digital Signal Processing. DSP is the study of signals in a digital representation and the processing methods of these signals. A digital signal processor is a specialized microprocessor designed specifically for digital signal processing, generally in real-time.
DUT	Device Under Test.
Dynaic Range	The ratio of the greatest un-distorted signal level and the noise level of the system, usually expressed in decibels.

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E

EDGE	Enhanced Data rates for GSM Evolution. EDGE is a digital mobile phone technology which acts as a bolt-on enhancement to 2G and 2.5G General Packet Radio Service (GPRS) networks. EDGE can be used for high speed packet switched applications such as Internet connection.
ESD	Electrostatic Discharge. A sudden flow of current when an excess of electrical charge, stored on an electrically insulated object, finds a path to an object at a different electrical potential, such as groud. Electronic devices are given an ESD classification depending on how sensitive they are.
Ethernet	The most widespread LAN technology in use.
ETSI	European Telecommunications Standards Institute. An independent non-profit organization of the telecommunications industry in Europe.

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F

Failure Analysis	A rigorous investigation of the fundamental causes of a failure.
Failure Rate (?)	The frequency with which something fails.
FCC	Federal Communications Commission. An independent US government agency regulating the use of the radio spectrum.
FDMA	Frequency Division Multiple Access. An access technology that allocates different carrier frequencies to different users.
FET	Field Effect Transistor. A transistor that relies on an electric field to control the conductivity of a channel.
FIT	Failure in Time. The number of probable failures in a given time period. Typically measured in units per 1E9 hours.
Frequency (f)	The rate at which an electromagnetic waveform alternates. Measured in (Hz). One hertz is equal to one cycle per second.
Frequency Band	The portion of the electromagnetic spectrum within a specified upper and lower frequency limit. Also known as Frequency Range.
Frequency Conversion	The translation of a signal from one frequency to another.
Frequency Hopping	A technique used to prevent interference in a transmit/receive system by rapidly switching the carrier among many frequency channels.
FSK	Frequency Shift Keying. A modulation technique for transmitting data in digital format over an analog carrier. FSK involves shifting the frequency of the carrier, usually between predetermined values.

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G

GaAs	Gallium Arsenide. A semiconductor material which has superior properties compared with Silicon, such has higher electron mobility. Used to make LEDs and microwave devices such as MMICs.
GaAs FET	A field effect transistor made with gallium arsenide.
Gain	The increase in signaling power that occurs as the signal is boosted by an electronic device. It's measured in decibels. Gain is the ratio between the amplitude of the output signal of a device or circuit compared to the amplitude of the input signal.
Gain Compression	The reduction in the gain of an electronic device caused by the non-linearity of the transfer function. Usually caused by overdriving the device. A common specification for PAs is output power at 1dB gain compression (P1dB).
Gain Control	A system whereby an external signal is applied ot hte control gain e.g. Variable Gain Amplifier.
Gain Flatness	The variation in gain (or attenuation) over the frequency band of interest, usually expressed in dB.
Giga (G)	A prefix denoting 10(9) or 1,000,000,000.
GPRS	General Packet Radio Service. Described at 2.5G, a packet switched connection which provides moderate speed data transfer using unused TDMA channels in the GSM network.
Green	A term meaning compliance with the RoHS directive, lead-free, and have limitations on other substances.
GSM	Global System for Mobile Communications. The most popular mobile phone standard in the world. GSM is a set of ETSI standards specifying the infrastructure for a digital cellular service, operating around 900 MHz or 1800 MHz in Europe, Asia, Australia, and around 1800 MHz in the Americas.

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H

Harmonic	A frequency which is an integer multiple of a fundamental frequency.
HBT	Heterojunction Bipolar Transistor. A bipolar transistor composed of layers of dissimilar semiconductor material which can handle very high frequencies.
Heat Sink	A structure that is mechanically attached to a device that generates heat, in order to lower the overall thermal impedance between the point source of heat within the device and its cooler surroundings.
HEMT	High Electron Mobility Transistor. A HEMT is a field effect transistor with a junction between two materials with different band gaps as the channel instead of an n-doped region.
Hermetic	Permanently sealed to the extent that transmission of gases and liquids is reduced or eliminated.
Hertz	A measurement of frequency in cycles per second. One hertz is one cycle per second. Abbreviated as "Hz".
HFET	Heterostructure Field Effect Transistor. Also known as HEMT.
High Frequency (HF)	Radio frequencies between 3 and 30 MHz. This range is often called shortwave.
Hybrid Coupler	A 3 dB 90° hybrid coupler is a four-port device that is used either to equally split an input signal with a reluctant 90° phase shift between output ports or to combine two signals while maintaining high isolation between the ports.
HSDPA	High-Speed Downlink Packet Access. A new mobile telephone protocol, sometimes referred to as a 3.5G, allowing for higher data capacity on WCDMA networks.

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I

IEEE	Institute of Electrical and Electronics Engineers. An international non-profit organization for the advancement of technology related to electricity.
IF	Intermediate Frequency. A frequency that has been reduced so that it can be processed. The IF frequency is the difference between LO and RF signal frequencies i.e. (LO-RF) or (RF-LO).
Input/Output	An electrical interface abbreviated as I/O.
Input	A signal fed into a circuit.
Insertion Loss (IL)	Also called attenuation. The difference in the amount of power received before and after something is inserted into the circuit. The ratio between the amplitude of the output signal of a device or circuit compared to the amplitude of its input signal. Insertion loss is normally expressed in decibels (dB).
Intermodulation Distortion (IMD)	Intermodulation distortion is generated by the transit of two or more uncorrelated signals entering a nonlinear device, such as a nonlinear amplifier. IMD is characterized by the appearance, in the output of a device, of frequencies that are linear combinations of the fundamental frequencies and all harmonics present in the input signals.
Interrogator	The reader, in RFID. It interrogates the tag to determine it's ID. The interrogation is an interaction between the reader and the tag. The tags are asked for their first bit as a 1. If more than one tag responds, then the reader (or interrogator) asks if the second bit is a 1. Again if more than one tag responds, then the tag continues until it finds a single tag that responds or not responds. If no tag responds, then it asks if the bit was a 0. Then it continues until the whole tag ID is complete.
IP3	Third Order Intercept Point is a figure-of-merit for non-linearity or distortion. Higher IP3 means better linearity and less distortion. IP3 is commonly tested with two input tones.
IS-95	Interim Standard 95. Known as a 2G mobile standard, IS-95 was the first CDMA based digital cellular standard and is widely deployed in North America and Asia.
ISM Band	Industrial, Scientific and Medical. Originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes.
ISO 9001	ISO 9001 is a rigorous international quality standard covering a company's research, development, design, production and service procedures. Compliance with the standard is increasing significance for vendors trading in international markets, in particular in Europe where ISO 9001 registration is widely recognized as an indication of the integrity of a supplier's quality processes.
Isolation	The difference in power, expressed in dB, between two different points in a system.
ITU	International Telecommunication Union. An organization established to standardize and regulate international radio and telecommunications.

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J

Joule (J)	A unit of energy or work, equal to one watt of power applied for one second.
JEDEC	Joint Electron Device Engineering Council. A US standards organization that is responsible for such things as electronic component package outline dimension.
JPEG	Joint Photographic Experts Group. JPEG is a glossy compression technique for photographic images.

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K

kilo (K)	A prefix denoting 10(3) or 1,000.
Kbps	Kilobit per second. One kilobit per second is equal to 1024 (or 2(10)) bits per second.
Kelvin (K)	A unit of absolute temperature, equal to 1/273.16 of the absolute temperature of the triple point of water and equivalent to one degree Celsius. Named after the British physicist William Thomson, first Baron Kelvin.
KHz	1000 Hertz, or 1000 cycles per second.
Killer App	Killer Application. The high-tech industry's lifelong dream. That dream is to discover a new application that is so useful and so persuasive that millions of customers will rush in, and throw money at you to buy your killer app. The term derives from the PC industry where a killer app was so powerful that it alone justifies the purchase of a computer.

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L

Lambda (?)	The 11th letter in the Greek alphabet. Lambda is used as the symbol for a wavelength.
LAN	Local Area Network. A data communication network operating within a building or small group of buildings and based on switched Eternet or WiFi.
L-Band	Long Wavelength Band. The optical band, or window, specified by the ITU-T at a wavelength range between 1565nm and 1625nm (nanometers). Frequency interval between 1 to 2 GHz.
LDMOS	Lateral Diffused MOS. A common FET technology used for high power RF transistors (>5W).
LED	Light Emitting Diode. A semiconductor device that emits incoherent narrow-spectrum light when electrically biased in the forward direction.
LFOM	Linear Figure of Merit. LFOM = OIP3/DC Power.
Linear	A circuit of component whose transfer function can be accurately described by a first order equation.
Linearity	The variations of a transfer function from the best straight line.
LMDS	Local Multipoint Distribution System. A point-to-multipoint broadband access technology that uses microwave signals operating between the 26GHz and 29GHz bands.
LNA	Low Noise Amplifier. An amplifier with low noise figure that is typically used at the front end of a radio receiver.
Load Pull	A technique to characterize the performance of an RF device by varying the load impedance. A similar technique applies to the input which is known as Source Pull. The outcome of the measurement is a set of contours on a Smith Chart.
LO	Local Oscillator. A circuit to generate a stable RF frequency that is mixed with the received RF signal to obtain an Intermediate Frequency (IF) output signal. The LO will operate at a frequency above (or below) the desired RF frequency by an amount equal to the IF frequency of the receiver.
Loss	The drop in signal level between two points in a network. Measured in decibels (dB).
Low Side LO Configuration	A receiver or down converter is said to have low side configuration when the LO frequency is less than the incoming RF signal. High side LO injection is the opposite.

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M

M	Mega. A prefix denoting 10(6) or 1,000,000.
m (Milli)	Milli. A prefix denoting 10(-3) or 0.001.
m (Micro)	Micro. One-Millionth.
Matching Network (MN)	An impedance transforming network operating over a known frequency range and used to match or optimize the terminal impedance to the system impedance i.e. 50ohm or 75ohm.
Maximum Junction Temperature	The highest junction temperature for the device to operate and remain reliable.
Maximum Stable Gain	The maximum gain obtainable from a two port network for it to remain stable. Measured in dB.
MCM	Multi-Chip-Module. In general they are considered to be the high density packaging of a number of bare semiconductor devices within a single module.
Mega (M)	A prefix denoting 10(6) or 1,000,000.
MESFET	Metal Oxide Semiconductor Field Effect Transistor. A field effect transistor (FET) often made of gallium arsenide that uses a metal-on-semiconductor gate.
Mixer	A three port device that employs at least one nonlinear component to perform multiplication of signals incident on two of the ports, typically designated RF input and LO input. Among the products of this multiplication at the third port (output) are signals whose frequencies are the sum difference of the LO and RF frequencies.
MMDS	Multichannel Multipoint Distribution Service. MMDS is a way of distributing cable television signals via microwave link from a single transmission point to multiple receiving points.
Modulation	The process of varying the characteristic of the carrier wave as the information to be transmitted. There are three basic types of modulation which are Amplitude, Frequency and Phase Modulation.
MOSFET	Metal Oxide Semiconductor Field Effect Transistor. A transistor that consists of electrodes (the source and drain)placed at opposite ends of a silicon channel. On top of the channel and between the electrodes an insulating layer of silicon dioxide is formed, on top of which a metal pad (the gate) is deposited. An electric field is induced into the channel as a result of a potential that is externally applied across the source and gate. This field modulates the resistance of the channel between the drain and source.
MMS	Multimedia Messaging Service. MMS is an evolution of SMS which allows the transmission of various kinds of multimedia content e.g. images, audio, and video clips.
MSL	Moisture Sensitivity Level. A standard for the time period in which an electronic component can be exposed to ambient room conditions (approximately 30°C/60%RH).
MTBF	Mean Time Between Failure. The average time a manufacturer estimates before a failure occurs in a component, a printed circuit board or a complete system.
MTTF	Local Mean Time to Failure. The average time between hardware breakdown or loss of service.

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N

Narrow Band	The methodology of gaining more channels (and hence more capacity) by splitting FM channels into channels that are narrower in bandwidth.
Noise	Unwanted electrical signals introduced into telephone lines by circuit components or natural disturbances which tend to degrade the performance of the line.
Noise Figure (NF)	The ratio (in dB) between the signal-to-noise ration applied to the input of the microwave component and the signal-to-noise ratio measured at its output. It is an indication of the amount of noise added to a signal by the component during normal operation. Lower noise figures mean less degradation and better performance.
Nominal Range	The read range at which an RFID tag can be read reliably.

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O

OEM	Orginal Equipment Manufacturer. A company that builds products or components which are used in products sold by another company.
Ohm	The practical uint of resistance. The resistance that will allow one ampere of current to pass at the electrical potential of one volt. Ohm's Law dictates the relation between the current, electromotive force and resistance in a circuit.
OIP3	3rd Order Intercept Point. Output IP3.
Operating Temperature Range	The specified temperature range over which a circuit or component is designed to operate without damage.

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P

P1dB	1 dB Compression Point is a figure-of-merit for output power. Higher compression point means higher output power. P1dB is at an input (or output) power such that the gain is lowered by one dB when compared to the gain at very low power.
Parameter	A limit, boundry, or threshold. A measurale electrical characteristic.
PCS	Persona Communication Systems or Services.
Power	The amount of work an electric current can do in a unit of time. Power is measured in WATTS. A WATT measures the amount of work done in lifting a quarter-pound weight a distance of one yard in one second.
Power Amplifier (PA)	An amplifier intended to increase the power of a signal enough to drive a load such as an antenna. Typically, power amplifiers also have large values for P1dB, indicating low distortion at high output power.

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Q

Q	Q factor - (1) Quality factor: the ratio of energy stored to energy dissipated. A measure of the relative losses in an inductor. It is also known as the quality factor, defined as the ratio of inductive reactance to effective resistance. Q is zero at the SRF of an inductor. (2) Also the symbol for electrical charge. (3) An omnipotent being in the Star Trek universe.
Q Factor	Ratio of energy stored to energy dissipated. A measure of the relative losses in an inductor. It is also known as the quality factor, defined as the ratio of inductive reactance to effective resistance. Q is zero at the SRF of an inductor. .
QAM	Quadrature Amplitude Modulation. A two-dimensional modulation used for ADSL, cable modems and proposed for VDSL. CAP is a special case of QAM. In QAM, a single carrier frequency is modulated in both sine and cosine components.
QPSK	Quadrature phase shift key modulation.
Quadrature	Orthogonal.
Quality Assurance	Systematic, planned, and documented activities designed to provide confidence that a product will meet specifications.
Quality Control	Activities that monitor, measure, and control the characteristics of a material, component, or product to documented specifications.
Quantizer	An analog-to-digital converter. A device that measures the magnitude of a time varying quantity in multiples of some fixed unit or quantum, at a specified instant or specified repetition rate, and delivers a proportional response that is usually in pulse code or digital form. The amplitude of the response signal is at each instant proportional to the number of quanta measured.
Quantum Efficiency	In a photodiode, the ratio of primary carriers (electron-hole pairs) created to incident photons. A quantum efficiency of 70% means 7 out of 10 incident photons create a carrier.
Quiescent Operating Point	The dc voltages, currents, and dissipation associated with a circuit while it is not being subjected to an input signal.
QUIP	Quad In-line Package. A packaging technique similar to a DIP but having two rows of pins along each long side, or a total of four rows.

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R

R	Symbol used to denote resistance in ohms.
Rack	A cabinet used to house components, which permits convenient removal of portions of the equipment for repair or examination. Original racks were standardized steel frames for 19-in. relay panels in telephone exchanges. Today, racks vary in size and shape to meet the specialized requirements of aircraft, computer, military electronics, and test equipment manufacturers. Racks accept equipment packages sometimes referred to as "bins," "modules," and "black boxes."
Rack and Panel Connector	Mating connectors of which one - usually the plug - is mounted inside a cabinet (rack). The receptacle is attached to the back of a sliding drawer, and mates with the plug when the drawer is fully inserted.
Radiated Frequency	The frequency of a signal that is transmitted by a radio, radar, navigational aid, or other radio frequency equipment. Radiated frequency is abbreviated as "RF."
Radiation Crosslinking	The act of crosslinking a material with ionizing radiation. (Most Raychem products are radiation crosslinked, with an electron beam as the form of ionizing radiation.) See also Crosslinking by Irradiation.
Radio	A collection of circuits that converts electromagnetic energy gathered from free space to electrical or sound energy, vice versa or both.
Radio Frequency	Any electromagnetic frequency from a few hertz up to frequencies in the infrared portion of the spectrum, to approximately 300 THz (terahertz).
Rated Current	The level of continuous DC current that can be passed through the inductor. This DC current level is based on a maximum temperature rise of the inductor at the maximum rated ambient temperature. The rated current is related to the inductor"s ability to minimize the power losses in the winding by having a low DC resistance. It is also related to the inductor"s ability to dissipate this power loss in the windings. Thus, the rated current can be increased by reducing the DC resistance or increasing the inductor size. For low frequency current waveforms the RMS current can be substituted for the DC rated current. The rated current is not related to the magnetic properties of the inductor (Also see Incremental Current and Saturation Current)
Rated Temperature	The maximum temperature at which a component can operate for extended periods with acceptable changes in its basic properties.
Rated Voltage	The maximum voltage at which an electric component can operate for extended periods without undue degradation.
Raychem Product Number	RPN - A 10-digit number (such as 123456-4-001) assigned to every standard product and every product manufactured on a special manufacturing order (SMO). The first 6 digits represent the PCN (Product Control Number), followed by a 1-digit MOD Code, and finally a 3-digit suffix. See also MOD Code and SMO.
Rayleigh Scattering	The scattering of light that results from small inhomogenei-ties in material density or composition.
RC filter	A filter made of resistor and capacitor
Reactance	Frequency-dependent impedance that is capable of storing but not dissipating energy. Reactance can be capacitive or inductive.
Rear Release Contacts	Connector contacts designed to be released and removed from the rear (wire side) of the connector. The removal tool engages the contact from the rear and pulls the contact out of the connector contact retainer.
Receiver Protector	A circuit or device that prevents incident high power, potentially-damaging signals from propagating to sensitive receiver components.
Receiver Sensitivity	The minimum received signal power level for which a receiver can produce a discernible output signal. The following equation for the sensitivity of a receiver shows the parameters that affect a receiving system"s sensitivity
Receptacle	Usually the fixed or stationary half of a two-piece multiple contact connector. Also the connector half usually mounted on a panel and containing socket contacts. In coaxial rf connectors the receptacle is usually the fixed or stationary one that is mounted on a panel. In shell type multiple-contact connectors the receptacle usually contains the pin contacts and is mounted on the "cold" side of the circuit such as in a drawer or "black box." Receptacles mate with plugs.
Recover (Heat-shrinkable Components)	Activation of the elastic memory principle (usually with heat) to cause a tubing or molded part to return to its original size.
Recovered ID	RID - In heat-shrink tubing, the guaranteed maximum internal diameter of tubing after being freely recovered.
Recovery Temperature	The minimum temperature required to fully shrink a product, that is, for the product to recover completely.
Recovery Time	The time interval required, after a sudden decrease in input signal amplitude to a system or transducer, to attain a stated percentage (usually 63 percent) of the ultimate change in amplification or attenuation due to this decrease.
Rectification	The process of converting alternating current into a unidirectional current, by removing or inverting that part of the wave laying on one side of the zero amplitude axis. There are two general types of retificitaion processes, half-wave and full-wave.
Rectifier	Device that allows current to flow in only one direction, such as a diode.
Redundancy	Any deliberate duplication, or partial duplication, of circuitry or information to decrease the probability of a system or communication failure.
Reduntant Operation	Parallel configuration of converters used in distributed power system to increase system reliabiltiy. Converters may be used in a "N+1" architucture.
Reflection	The backward transmission of electrical energy caused by a change in impedance.
Reflection Coefficient	At a specified plane in a uniform transmission line, the vector ratio of the reflected to the incident waves. The symbol for reflection coefficient is "G".
Reflection Loss	The part of transmission loss due to power reflected by a discontinuity (impedance mismatch) in a transmission line.
Reflective Codes	Codes which appear to be the mirror image of normal counting codes.
Refractive Index	(n) The ratio of the speed of light in a vacuum (c) to the speed of light in an alternate medium(v). n=c/v
Regenerative repeater	A repeater designed for digital transmission that bothamplifies and reshapes the signal.
Regulation	Ability of a converter to maintain an output voltge to within specified limits under varying conditions of input line and output load. Also see Linear Regulation.
Relay	An electrical device that is designed to interpret input conditions in a prescribed manner, and - when specified conditions are met - to respond by causing contacts to operate, or similar abrupt changes in associated electric control circuits. Inputs are normally electric, but may be thermal, mechanical, or other qualities. Limit switches and other such simple devices are not to be considered as relays. A relay is an electrically operated switch.
Relay Contact Bounce	Undesired intermittent closure of open contacts or opening of closed contacts. This may occur either when the relay is operated or released, or when the relay is subjected to external shock or vibration. The term "bounce" is normally associated with internal causes.
Reliability	The probability that a device, component or system will perform adequately for the expected time under given conditions.
Remote Sensing	Using sense leads connected at the output load provides feedback to voltage regulation circuits of a converter. This arrangement is used to compenate for voltage losses from long leads to a load. Also see Local Sensing.
Removable Contact	A contact that can be mechanically joined to or removed from an insert. Usually special tools are required to lock the contact in place or remove it for repair or replacement.
Repeater	A device that receives, amplifies (and perhaps reshapes), and retransmits a signal. It is used to boost signal levels when the distance between repeaters is so great that the received signal would otherwise be too attenuated to be properly received.
Repetition Rate	The number of occurrences of an event per unit time.
Reset	The operation of returning an electronic, or electrical, device to its original or "start" point. Most AMP data terminals offer manual reset, automatic reset, or both.
Residual Flux	The flux that remains in a core when the applied MMF is returned to zero.
Residual FM	Undesirable, apparent frequency modulation of a signal source caused by noise or spurious signals.
Residual Forces	The elastic forces which remain after each contact member has been deformed or deflected to its final state.
Resiliency	That property of a strained body which enables it to recover its size and shape as it is unloaded after some initial deformation.
Resist	A material such as ink, paint, metallic plating, etc used to protect the desired portions of the conductive pattern from the action of the etchant, solder, or plating.
Resistance	(1) The frequency-invariant opposition to current flow, abbreviated as "R." The unit of resistance is the ohm (?). (2) The resistance of a PolySwitch device under specified conditions (e.g., 20¡C), before connection into a circuit. Devices of a particular type will be delivered with a range of resistances; therefore, a minimum value, Rmin, and/or a maximum value, Rmax, are often given.
Resistance Binned Devices	Resistance binned devices are supplied such that all parts in one package are within 0.5 ? of each other. Individual binned packages are supplied from the full resistance limits of the specified product.
Resistance Sorted Devices	Resistance sorted devices (part number suffix "Rx") are supplied with resistance values that are within specified limits of the product"s full range of resistance.
Resistor	A circuit component which offers resistance to the flow of electric current. Its electrical size is specified in ohms or megohms (1 megohm = 1,000,000 ohms). A resistor also has a powerhandling rating measured in watts, which indicates the amount of power which can safely be dissipated as heat by the resistor.
Resonance	The frequency at which capacitive reactance and inductive reactance are equal and therefore cancel one another"s effects.
Resonant Converter	Switching converter technology in which a resonant tank circuit operating at very high frequencies is used to transfer energy to the output.
Resonant Frequency	The frequency at which the inductive and capacitive reactances of a circuit are equal in magnitude, thereby canceling each other"s effects. The symbol for resonant frequency is "fR."
Responsivity	The ratio of a photodetector I s electrical output to its optical input in amperes/watt.
Retaining Ring	A small circular steel ring, often resembling the letter "C," that is usually inserted into a slot in a pivot pin to hold the pin in a specified position.
Retaining Spring	Used to balance contact pressure and increase board retention when a single-sided pc board is used in a connector designed for two-sided boards. A limited number of springs are used to replace the contacts in the unused side of the connector.
RETMA	Abbreviation for Radio-Electronics-Television Manufacturers" Association. Now changed to Electronics Industries Association (EIA).
Return	Common terminal on the output of a DC-DC converter. It is the return current path for the output. Also see Common.
Return Loss	A measure of the signal reflected back toward the transmitter as a result of impedance variations in the cabling system.
Return Reflection	Reflected optical energy that propagates backward to the source in an optical fiber.
Return Reflection Loss	The attenuation of reflected light; high return loss is desirable, especially in single-mode fibers.
Reverse Current	Current flowing from input to output or input to case of an isolated converter at a specified voltage level.
Reverse Voltage Protection	Converter feature that prevents damage to internal components if a reverse voltage is inadvertently applied to the input or ouput terminals.
Reversible Temperature Coefficient	Changes in flux which occurs with temperature change. They are spontaneously regained when the temperature is returned to its original point. There are two values reported: reversible temperature coefficients of inductance (Br) and Coercivity (Hci). The temperature range over which they have been measured and specified should be stated. Most materials exhibit a non-linear response with temperature.
RF	Radiated Frequency. Also used as an abbreviation for Radio Frequency, used as a noun or adjective.
RF Frequency	The frequency in the portion of the electromagnetic spectrum that is loosely considered to be between above the audio-frequency portion and the infrared portion. It is normally 20 kHz to hundreds of GHz.
RF Impedance	The impedance of a circuit or component at high frequencies.
RFI	RFI is an acronym for Radio-Frequency Interference. It is an older and more restrictive term that is used interchangeably with EMI (Also see EMI.)
RFP	Request for Proposal
RG/U	RG/U is used to designate coaxial cables that are made to a Government specification. In the case of RG58/U, the "R" means RADIO FREQUENCY, the "G" means GOVERNMENT, the 58 is the number assigned to Government approval, and the "U" means it"s a UNIVERSAL specification.
Ribbon Cable	Round conductor flat cable. A form of flexible flat cable (ffc) consisting of parallel round conductors in a flexible insulating material and designed for mass termination.
Ribbon Cable	Flat cable with conductors that have been individually insulated together. Its structure is usually characterized by individual colors of insulation for each conductor, although a single color may be used for all conductors.
RID	Recovered Inside Diameter
Right-Angle Edge Connector	The plug is mounted to a chassis or back panel, and the receptacle is mounted along an edge of - and soldered to - the circuits of a printed circuit board. Pins of the receptacle are generally simple rod stock bent at right angles and molded into the receptacle insert. The board and receptacle assembly is mated with the plug to complete circuit wiring.
Ripple	Variation in magnitude.
Ripple and Noise	Periodic and Random Deviation - Noise and ripple voltage superimposed on a converter"s DC output. Typically specified at full load, it is expressed in peak-to-peak or RMS volts over a given bandwidth.
Ripple Voltage	The periodic alternating voltage imposed on the voltage output of a switching voltage converter. The ripple voltage is normally specified as a peak-to-peak value.
Rise Time	The time required for a component, or logic circuit, to change from the quiescent to the transient state, when an input is applied (ie elapsed time between application of input and attainment of full output level).
Riser	Backbone cabling connecting telecom closets situated vertically on separate floors.
RJ11	A wiring pattern for 6-position modular jacks.Used to refer to the jacks themselves.
RJ21	A wiring pattern for a 25-pair (AMP CHAMP) connector.Also used to refer to the connectors themselves.
RJ45	A wiring pattern for8-position modular jacks.Used to refer to the jacks themselves.
RMA Flux	Rosin-mildly-activated flux.
Rmax	The resistance of a PolySwitch device under specified conditions (e.g., 20¡C), before connection into a circuit. Devices of a particular type will be delivered with a range of resistances; therefore, a minimum value, Rmin, and/or a maximum value, Rmax, are often given.
RMC	An NMEA message
Rmin	The resistance of a PolySwitch device under specified conditions (e.g., 20¡C), before connection into a circuit. Devices of a particular type will be delivered with a range of resistances; therefore, a minimum value, Rmin, and/or a maximum value, Rmax, are often given.
RMS	Root Mean Square - The effective value of an alternating current, corresponding to the direct current value that will produce the same heating effect.
Robotics	The theory and application of robots, a completely self-contained electronic, electric, or mechanical device, to such activities as manufacturing.
Roentgen	The amount of radiation that will produce one electrostatic unit of ions per cubic centimeter volume.
ROM	Read-only memory. A memory, usually a semiconductor chip, in which the information is permanently stored. ROMs offer random-access read capabilities. May be programmed during manufacture or by the user. Some are reprogrammable. See PROM and EPROM.
Root Mean Square	RMS - The effective value of an alternating current, corresponding to the direct current value that will produce the same heating effect.
Rope Lay	A type of conductor lay that uses stranded conductors as components to build a larger conductor.
Rotary Switch	A multiposition switch operated by rotating a control knob (attached to its shaft) either clockwise, counterclockwise, or both.
Rotor	The rotating member of a motor that includes a shaft. Commonly called the armature.
Routine	A series of computer instructions for performing a specific, limited task.
Royer Converter	Self-oscillating, push-pull switching circuit configuration commonly used in low cost, low power DC-DC converters. Also called the classical converter.
RPN	Raychem Product Number - A 10-digit number (such as 123456-4-001) assigned to every standard product and every product manufactured on a special manufacturing order (SMO). The first 6 digits represent the PCN (Product Control Number), followed by a 1-digit MOD Code, and finally a 3-digit suffix. See also MOD Code and SMO.
RS 232, 422, 449+A2043	A series of standards defining the physical link between units of data communication equipment.
RT and RW specifications	Specification that describes standard product properties. Qualification and acceptance inspection criteria are incorporated into RT and RW specifications. RT and RW specifications are issued and controlled by the Specifications Group.
RTCA	Radio Technical Commission for Aeronautics (For WAAS & EGNOS services)
RTCM	Radio Technical Commission For Maritime Services (Special Committee 104 - A committee created for the purposes of establishing standards and guidance for interfacing between radio beacon-based data links and GPS receivers, and to provide standards for ground-based differential GPS stations. )
RTK	Realtime Kinematic
Rubber	An elastomer capable of rapid elastic recovery. Specifically, natural rubber, the standard of comparison for elastomers.
RZ Data Rates	Return to zero. A data transmission format in which the circuit must switch from 0 to 1 and back to 0 in a single clock pulse each time a logical 1 is presented. RZ rates are generally half those of NRZ rates. See also NRZ data rates.
Radio	Rosin-activated flux.

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S

S-Band	The frequency interval from 2 to 4 GHz.
S-HDSL	Single pair transmission using HDSL technology, normally 2B1Q.
Scribing	The scratching of a brittle substrate, such as alumina or silicon, to ensure cleavage along the scratch line. Wafers are scribed and then broken to produce integrated circuit chips.
Safetying	A term used to cover the use of product features designed to prevent the loosening of hardware, or other mating elements, under conditions of shock and vibration. Elements drilled for safety wiring would be an example of this type of feature.
Saturable Reactor	Describes the main element of a magnetic amplifier used to control electrical power such as for electrical resistance element heating of furnaces.
Saturated	The state of operation of a device or circuit in which there is no increase in output for an increase in input.
Saturation	The condition in which a further increase in one variable produces no further increase in the resultant effect. The condition occurring when a transistor is driven so hard that it becomes biased in the forward direction. In a switching application, under saturation conditions the charge stored in the base region prevents the transistor from turning off quickly.
Saturation Current	The DC bias current flowing through tile inductor which causes the inductance to drop by a specified amount form the initial zero DC bias inductance value. Common specified inductance drop percentages include 1-% and 20%. IT is useful to use the 10% inductance drop value for ferrite cores and 20% for powdered iron cores in energy storage applications. The cause of the inductance to drop due to the DC bias current is related to the magnetic properties of the core. The core, and some of the space around the core, can only store a given amount of magnetic ~ density. Beyond the maximum flux density point, the permeabilty of the core is reduced. Thus, the inductance is caused to drop. Core saturation does not apply to air-core inductors (Also see Incremental Current and Permeability)
Saturation Flux Density	The flux density value at which a given material saturates.
SAW	Surface acoustic wave. Often short for surface acoustic wave filter.
SC Connector	A duplex optical fiber connector. The standard connector for optical fiber per the 568 cabling standard.
Scale Factor	One or more coefficients used to multiply or divide quantities in a problem in order to convert them to a given magnitude (eg plus one to minus one).
SCD	Specification Control Drawing - Drawing that defines configuration and material parameters. Issued and controlled by the specifications group, SCDs are frequently used in conjunction with RT Specifications for Thermofit products.
Schematic	A "scheme" for presenting information. Thus, a circuit schematic - in diagrammatic form - indicates the components, wiring, and connections of the circuit.
Schmitt trigger	A bistable trigger circuit that converts an input signal into a square-wave output signal by switching action, triggered at a predetermined point in each positive and negative swing of the input signal.
Schottky	A metal-semiconductor junction that has a nonlinear voltage versus current characteristic.
Schottky TTL	A type of TTL notable for faster operating speeds than standard TTL.
Scoop-proof	A feature that prevents the damage of contacts during misaligned mating.
Scratch Pad Memory	A computer information store that interfaces directly with the central processor. It is optimized for speed and has a limited capacity. Its purpose is to supply the central processor with the data for the immediate computation without the delays that would be encountered by interfacing with the main memory.
Screw-Machine Contact	A contact which is machined from solid bar stock.
Scribing	The scratching of a brittle substrate, such as alumina or silicon, to ensure cleavage along the scratch line. Wafers are scribed and then broken to produce integrated circuit chips.
Self Resonant Frequency	SRF - The frequency at which an inductor"s distributed capacitance resonates with the inductance. The inductive reactance and the capacitive reactance are equal. The inductor acts as a pure resistance. The Q of an inductor is equal to zero at the SRF.
SEM	Scanning electron microscope, in which a beam of electrons systematically sweeps over the specimen. The intensity of the secondary electrons generated at the point of impact is measured, and the resulting signal is fed to a CRT display, which is scanned in synchronism with the scanning of the specimen.
Semiconductor M	Materials whose electrical conductivity is between that for good conductors and that for good insulators. Their conductivity may be changed by heat, light, electric field, or magnetic field. Examples include: germanium, lead sulfide, lead telluride, selenium, silicon, and silicon carbide. A semiconductor device, such as a transistor, is frequently referred to simply as a "semiconductor."
Semiconductor Device	A solid state electronic device in which conduction takes place within a semiconductor. By careful processing, certain semiconductors (primarily germanium and silicon) can be used in these electronic devices which perform many or all of the functions of thermionic tubes (vacuum tubes). In many applications, their small size, long life, and low power requirements make them superior to tubes.
Sense Line	Output line used in a remote sensing connection to route the output voltage (at the load) back to the control feedback loop. Also see Remote Sensing.
Sensitivity	Measure of the ability of a device or circuit to react to a change in some input. Sensitivity can also be the minimum or required level of an input necessary to obtain rated output, as in an amplifier. For a fiber-optic receiver, the minimum optical power required to achieve a specified level of performance, such as a BER.
Sensitivity switch	A switch having a snapaction, microgap mechanism which is operated directly by a defined force through a defined travel.
Separable Part	A replaceable part, designed to be removed without risk of destroying or damaging adjacent elements. Crimping, chemical bonding, etc preclude assurance of safe removal, and parts so attached would not be deemed separable. Protective coatings, solder, etc normally do not preclude safe removal, and parts so treated - barring other factors - may still be classified as separable.
Sequencer	A mechanical or electronic device used to initiate and control the predetermined sequence of a series of events.
Sequencing	The process of performing a series of operations in a predetermined order.
Serial Memory	A memory whose information media is continuous. Data is identified in its content or form. Data may be obtained only by performing a serial search through the contents of the memory. A magnetic tape is serial.
Series	Connecting components in a circuit end-to-end to provide a single path for current flow.
Series Operation	Master-slave configuration in which two or more isolated converters are connected to obtain a hgher output voltage level (converter inputs connected in parallel) or wider input voltage range (converter inputs connected in series) than that obtainable from one module. Also see Master-Slave Operation.
Series Resistance	The real part of the complex impedance of a semiconductor device. The resistance of the semiconductor package, die attach and bond wire are typically included in series resistance.
Series-Shunt	The circuit configuration including two components, the first in series with the transmission line and the second in shunt with the transmission line.
Service Life	Period of time during which the product is expected to perform satisfactorily.
Service Loop	The extra cable required at a breakout to facilitate maintenance and servicing.
Service Rating	The maximum voltage or current that a termination is designed to carry continuously.
Settling Time	The time required for the device to attain 90 percent of the detected RF output referenced to the 10 percent level.
Sheath	The outer covering or jacket over the insulated conductors to provide mechanical protection for the conductors. Also known as the external conducting surface of a shielded transmission line.
Shelf Life	Generally, the length of time a product or material may be stored without deterioration. Specifically, the length of time during which shrink tubing will retain its expanded ID and return to its recovered ID. Usually not a concern—except for some “amnesic” materials. See Amnesia.
Shell	The outside case, usually metallic, into which the insert (body) and contacts are assembled. Shells of mating connector halves usually provide for proper alignment and polarization as well as for protection of projecting contacts.
Shield	A conducting layer placed around an insulated conductor or cable to limit the penetration, or escape, of electric or electromagnetic fields, thereby preventing electromagnetic interference. The shield may be formed of metallic braid, metal tape, metal-backed foil, metal tube, or conductive polymer. Usually grounded, the shielding is carried through the connector shell, or through a special internal shell in the case of individual coaxial contacts.
Shielded Inductor	An inductor designed for its core to contain a majority of its magnetic field. Some inductor designs are self shielding. Examples of these are magnetic core shapes which include toroids, pot cores and B-Cores. Magnetic core shapes such as slug cores and bobbins require the application of a magnetic sleeve or similar method to yield a shielded inductor. It should be noted that magnetic shielding is a matter of degree. A certain percentage of the magnetic field will escape the core material. This is even applicable to toroidal cores as lower core permeabilities will have higher fringing field than will high permeability toroidal cores (Also see Closed Magnetic Path.)
Shielded Room	A room, used for EMI testing, having highly conductive walls that isolate the interior from the exterior to contain energy within the room and to prevent outside energy from entering the room.
Shielding	(1) A conducting envelope, composed of metal strands, that encloses a wire, group of wires, or cable, so constructed that substantially every point on the surface of the underlying insulation is at ground potential or at some predetermined potential with respect to ground. (2) An isolation barrier placed around a circuit component to prevent interaction of its electric and/or magnetic fields with those of nearby elements. Shielding protects a circuit against crosstalk.
Shielding Effectiveness	A measure of the performance of a shield, typically expressed in decibels as (1) the ratio of energy incident on the shield to that emerging on the other side or (2) the ratio of energy emitted from an unshielded sample to the energy emitted by the same sample when it is shielded.
Shift	To move information serially right or left in a register(s). Information shifted out of a register may be lost, or it may be re-entered at the other end of the register.
Shock	(1) An abrupt impact applied to a stationary object. Usually expressed in gravities (g). (2)An abrupt and nonperiodic change in position, characterized by suddenness, and by development of substantial internal forces.
Shore	A scale for comparing hardness. Higher Shore values represent harder materials. The hardness of a polymer, for example, is usually represented as Shore A or Shore D, with D being harder.
Short Circuit Protection	Maximum steady-state current level at which the power switch output is regulated in response to an overcurrent fault.
Shot noise	Noise caused by random current fluctuations arising from the discrete nature of electrons.
Shrink Ratio	An expression of how much the inside diameter of shrink tubing will reduce in size when recovered. The inverse of the expansion ratio. See also Expansion Ratio.
Shunt	In parallel with; connector used to common two circuits.
Shunt Regulator	Linear regulator (internal or external to the converter) placed in parallel with the load to achieve a constant voltage across the load. Also see Linear Regulation, Post Regulation and Series Regulator.
SHV	Standard High Voltage - A quick connect/disconnect connector series employing bayonet lock coupling and designed to operate safely up to 5000 volts ac. It is the industry standard connector, specified by the National Bureau of Standards (NBS) for high voltage use by the Atomic Energy Commission (AEC).
Sideband Suppression	In a mixer or modulator, the degree to which undesired sidebands are reduced in amplitude.
Sign Bit	Computers generally indicate whether a number is positive or negative by a sign bit, which is usually located adjacent to the most significant numerical digit. Usually zero (0) is used for positive (+) and one (1) for negative (-).
Signal Cable	A cable designed to carry current of less than 12 amperes per conductor.
Signal Frequency	In a mixer or detector, this is the desired RF or microwave frequency containing information (modulation). This is the frequency that is to be converted to a different (normally lower) frequency.
Signal Rise Time	The time for a signal to switch from low to high, usually measured between 10% and 90% of the maximum amplitude.
Signal-to-Noise Ratio	SNR - The ratio of signal strength to noise level in an electronic system.
Significant Digit	A digit that contributes to the preciseness of a number. The number of significant digits is counted beginning with the digit contributing the most value, called the most significant digit, and ending with the one contributing the least value, called the least significant digit.
Silicon	The semiconductor material most widely used for transistors, diodes, and monolithic integrated circuits. A brittle, gray, light metal.
Silicon Dioxide	The result of oxidizing silicon quartz. Selectively etched silicon dioxide permits the selective doping that generates components in monolithic integrated circuits.
Silicon Nitride	A silicon compound that is deposited on the surface of silicon monolithic integrated circuits to improve their stability. The nitride is relatively impervious to some ions that penetrate silicon dioxide. Best stability is obtained by a combination of silicon nitride and silicon dioxide. Charge storage at the interface of the nitride and dioxide layers has resulted in memory devices with extremely long retention times.
Silicon Oxide	A generic term referring to an unspecified mixture of silicon monoxide and silicon dioxide, such as may be deposited on a silicon integrated circuit as an insulator between runs in multilevel metallization.
Silicon-Controlled Rectifier	SCR - A semiconductor device capable of only two stable states. When "off," it blocks the flow of electricity in either direction. A small triggering voltage to its gate turns it "on," and allows the flow of electricity in the forward direction only. When "on," the SCR acts just like a conventional rectifier. To turn it "off," voltage to the anode must be removed, or reduced to a potential less than that being applied to the cathode.
Silicon-Controlled Switch	SCS - A semiconductor device with leads to all four regions. Can be integrated with transistors in monolithic integrated circuits. Useful as a small SCR or complementary SCR.
Silo	A housing construction feature which increases the electrical current creepage path for high voltage ratings. May also provide polarization for mating connectors.
Simple Network Management Protocol	SNMP - A network management standard initially established to allow multi-vendor networking devices to be managed more easily with common management tools.
Simple Winding	A winding for a toroidal core which results in 78% of the cores inside diameter remaining. Often times this will produce a single layer winding.
Simplex	A circuit which allows telecommunications in only one direction at a time; a one-way path for telegraph-type signals.
Simplex cable	A term sometimes used for a single-fiber cable.
Simplex transmission	Transmission in one direction only.
Sine Wave	A wave which can be expressed as the sine of a linear function of time, space, or both. A waveform (often viewed on an oscilloscope) of a pure alternating current or voltage.
Single Ended Mixer	The simplest form of mixer, which consists of a single nonlinear impedance connected across an unbalanced transmission line, to which RF and LO signals are applied and from which the IF signal is obtained.
Skew	Any out-of-squareness of the cut end of a piece of tubing after shrinking.
Skewing Of The Loop	When an air gap is added to a magnetic path, the hysteresis loop is made to lean over (permeability is reduced). It is said to be skewed or sheared.
Skin Effect	Skin effect is the tendency for alternating current to flow near the surface of the conductor in lieu of flowing in a manner as to utilzie the entire cross-sectional area of tile conductor. Ths phenomenon causes the resistance of the conductor to increase. The magnetic field associated with the current in teh conductor causes eddy currents near the center of the conductor which opposes the flow of the main current flow near the center of the conductor. The main current flow is forced further to the surface as the frequency of the alternating current increasing (Also see Litz Wire.)
Sleeve	The insulated, or metallic, covering over the barrel of the terminal.
Slotted Tongue	A terminal that has a slot rather than a hole in the tongue, so that the terminal can be engaged and disengaged from a stud without completely removing the nut.
Slug Core	A core shaped like a rod, with the winding(s) placed around the diameter.
SMA connector	A radio-frequency connector covered by Military Specification. It has an impedance of 50 ohms and an operating frequency range to 12.4 GHz.
Small Signal	The magnitude of an AC signal which, when its amplitude is halved or doubled, the characteristic under measurement does not change.
Small Signal Analysis	The consideration of the performance of a circuit or device under small signal conditions
Small-Scale Integration	SSI - A single circuit function implemented in monolithic silicon. In complexity, a circuit of less than 10 gates.
SMD	Surface Mount Device
Smith Chart	A mapping of the complex impedance plane onto a polar plot. A Smith chart consists of circles of constant resistance that intersect at Z = Â and arcs of constant reactance that also intersect at Z = Â. The horizontal diameter of the Smith chart represents pure resistances from a short (0 W) at one end to an open (Â W) at the other end. The Smith chart was developed by Philip H. Smith in the late 1930"s.
SMO	Special Manufacturing Order - An order to evaluate manufacturing and production capability for a new or changed design for a customer and to provide development samples of potential products for customers. SMO products are separate and distinct from standard products. New, potential products are usually run as SMO products for a minimum of three times before being considered for manufacture as a standard product.
SMR	Specialized mobile radio. A communications service at 800 MHz and 900 MHz used to provide dispatch messaging and cellular communications.
SMS	Short Message System
Snap Time	The time required for a varactor or step recovery diode to change from the conducting to non-conducting state after reverse bias is applied, excluding the time required for charge to be conducted from the junction. It is normally measured from the 90 percent to 10 percent reverse current states. Also called transition time
SNR	Signal-to-noise ratio - The ratio of signal strength to noise level in an electronic system.
Socket Contact	A female contact designed to mate with a male contact or pin. It is normally connected to the "hot" side of the circuit because the housings that accept sockets usually fully surround, insulate, and protect the contact.
Soft Magnetic Material	A ferromagnetic material that is easily magnetized and demagnetized.
Soft Start	Converter input circuit that limits the inrush of current at turn on.
Software	Computer programs.
SOG	Speed over Ground. (The actual speed the GPS unit is moving over the ground)
SOHO	small office/home office
Solder	An alloy that can be melted at a fairly low temperature, for use in joining metals having much higher melting points. An alloy of tin and lead in approximately equal proportions is the solder most often used for making permanent joints in circuits.
Solder Contact	A contact or terminal having a cup, hollow cylinder, eyelet, or hook to accept a wire for a conventional soldered termination.
Solder Cup	A tubular end of a terminal into which a wire conductor is inserted prior to being soldered.
Solder-Eyelet	A solder-type terminal, having a hole at its end through which a wire can be inserted prior to being soldered. See also eyelet.
Solderability	The property of a metal surface that allows it to be readily wetted by molten solder. See also Wetting.
Soldering	A process of joining metallic surfaces with solder without melting the base metal.
Solderless	Without the use of solder.
SolderSleeve Device	A device of flux-coated solder preform encapsulated in a heat-recoverable plastic sleeve. Upon the application of heat, the flux and solder will melt and flow as the sleeve recovers, forcing the solder around and onto the metallic parts being joined, thus forming an electrically insulated and strain-relieved joint.
Solenoid	An electrical conductor wound as a coil (helix) with a small pitch. When activated with an electrical current, it draws a movable core into the coil.
Solid Conductor	A conductor composed of one single strand.
Solid State	In electronics, having or pertaining to circuits that contain semiconductors. Note: In electro-optics, used to refer to lasers and related devices made of solid crystalline or amorphous materials other than semiconductors.
Soliton	An optical pulse that does not disperse over distance.
Solvent Resistance	The ability of a material to retain physical and electrical properties after being immersed in specific solvents.
Solvent Resistance Test	A test described in Raychem"s PS300 publication to test the durability of the markings on PolySwitch devices when exposed to various solvents.
SOM	Start of message.
SONET	Synchronous Optical Network- A recently emerging networking standard that utilizes fiber optics to create backbone networks, capable of transmitting at extremely high speeds and accommodating gigabit-level bandwidth.
Sorted	Binned refers to resistance-matched devices, which are supplied such that all parts in one particular package (or reel) are within 0.5 ohms of each other (1.0 ohms for TR250-080T devices). Individual matched packages are supplied from the full resistance range of the specified device. The benefit is that resistance-matched devices reduce the tip-ring resistance differential, reducing the possibility of line imbalance. Sorted devices are those that are supplied with resistance values that are within specified segments of the device"s full range of resistance, giving greater design flexibility.
Source	(1) The terminal at one end of the channel of a field effect transistor by which electron or hole current enters the channel. This terminal corresponds to the emitter in a bipolar transistor. (2) Power bus that drives the DC-DC converter. Also see Bus. (3) The light emitter, either an LED or laser diode, in a fiber-optic link. Spectral width A measure of the extent of a spectrum. For a source, the width of wavelengths contained in the output at one half of the wavelength of peak power. Typical spectral widths are 20 to 60 nm for an LED and 2 to 5 nm for a laser diode.
Spare Inputs	Extra inputs or unused inputs.
SPC	Statistical Process Control - The use of statistical techniques such as control charts to analyze a process or its output so as to take appropriate actions to achieve and maintain a state of control and to improve the capability of the process.
SPC	Silver-plated copper.
SPDT	Single-pole, double-throw - A three-contact switching arrangement which connects a circuit to either one of two alternate connections (called Form C).
Specific Gravity	The density (mass per unit volume) of any material divided by that of water at a standard temperature.
Specific Inductive Capacity	(Also K) The ratio of the capacitance between two electrodes with a solid, liquid, or gaseous dielectric, to the capacitance with air between the electrodes. Also called permittivity and dielectric constant. Generally low values are desirable for insulation.
Specification Control Drawing	SCD - Drawing that defines configuration and material parameters. Issued and controlled by the specifications group, SCDs are frequently used in conjunction with RT Specifications for Thermofit products.
Specs	Abbreviation for specifications. A control document which establishes the parameters that a given product, or type of product, must meet. Firms use specifications for control in manufacture, Government agencies use them for control in procurement, and other bodies - such as UL - use them as a basis for approval.
Spectral Dispersion	Due to a band of wavelengths (colors) put out by a light source. Each separate color has a different speed through the fiber causing different colors to arrive at different times, making the pulse appear longer than originally generated.
SPICE	Semiconductor Parameter In Circuit Emulator - a software package that emulates circuit performance utilizing time domain analysis
Splice	A joint connecting conductors with good mechanical strength and conductivity; a terminal that permanently joins two or more wires.
Splitter	A component that divides the power from a signal into two or more parts
Spring Properties	The relationship between applied force and resulting deflection which characterize the potential loading conditions of a given system (ie, usually refers to the elastic properties of a system).
Spring-finger Action	A type of spring design - as used in a printed circuit connector or a socket contact - which permits easy, stress-free spring action to provide contact pressure and/or retention.
SPS	Standard Positioning Service (see also PPS)
SPST	Single-pole, single-throw - A two contact switching arrangement which either opens or closes one circuit. This circuit may be normally open (NO, called Form A), or normally closed (NC, called Form B).
Spurious	Undesired signals present at the output of a device under test that are neither harmonics nor intermodulation products, sometimes expressed as a percentage of or decibels below the carrier.
Sputtering	A thin film technique in which the film material is ejected from the surface by the action of ion bombardment.
Square Wave	An excitation that consists of an abrupt on/off cycling of the voltage. This typically goes in both the positive and negative direction. A positive-only square wave would be typical of pulse excitation.
Square-Law Detection	Detection of an RF/microwave signal where the magnitude of the detected video output voltage is proportional to the square of the RF input voltage
Square-Law Detector	A detector circuit or device whose video output voltage is proportional to the square of the RF input voltage
Squareness Ratio	The ratio of residual flux density to the maximum (saturation) flux density.
SRF	Self Resonant Frequency - The frequency at which tile inductor;s distributed capacitance resonates with the inductance. It is at this frequency that the inductance is equal to the capacitance and they cancel each other. The inductor will act purely resistive with a high impedance at the SRF point. The distributed capacitance is caused by the turns of ~re layered on top of each other and around the core. This capacitance is in parallel to the inductance. At frequencies above the SRF, the capacitive reactance of the parallel combination will become the dominant component. Also, tile Q of the inductor is equal to zero at the SRF point since the inductive reactance is zero. The SRF is specified in Mhz and is listed as a minimum value on product data sheets (Also see Distributed Capacitance)
SSI	Small Scale Integration - A single circuit function implemented in monolithic silicon. In complexity, a circuit of less than 10 gates.
ST connector	A bayonet style optical fiber connector.An alternate style per the 568 standard.
Stamped and Formed contact	A contact which is stamped from a flat sheet of metal and then formed through a progressive die.
Standby Current	Current drawn by a converter when it has no load and has been shut down by a logical inhibit signal.
Standing Wave Ratio	The ratio of the maximum magnitude of a standing wave to the minimum magnitude. SWR is indicative of the degree to which there is a mismatch between the characteristic impedance of the transmission medium and its load. A standing wave ratio of 1:1 indicates a perfect match (all the power incident on the load is absorbed by the load), while SWR = Â indicates a complete mismatch (all the power incident on the load is reflected by the load).
Standing Waves	The sum along a transmission medium of incident and reflected waves, characterized by maxima and minima along the medium.
Standing-Wave	Distribution of current and voltage on a transmission line, resulting from two sets of waves traveling in opposite directions.
Standing-Wave Ratio	Distribution of current and voltage on a transmission line, resulting from two sets of waves traveling in opposite directions. SWR - The ratio between maximum and minimum current, or voltage, along a line. It is a measure of the mismatch between the load and the line, and is equal to 1 when the line impedance is perfectly matched to the load. (In that case the maximum and minimum are the same, as current and voltage do not vary along the line.) The perfect match would be referred to as a 1 to 1 ratio. Vswr is voltage standing wave ratio.
Star Coupler	A fiber-optic coupler in which power at any input port is distributed to all output ports.
Star Network	A network in which all terminals are connected through a single point, such as a star coupler.
Start of Message	SOM - Usually a unique character in a data stream that indicates the beginning of a block of information data. See also start sentinel.
Start Sentinel	The binary coded character used to determine the start of a message on a magnetic stripe credit card.
State Machine	A sequential network is used to control a digital system that carries out a step by step procedure or algorithm
Statistical Process Control	SPC - The use of statistical techniques such as control charts to analyze a process or its output so as to take appropriate actions to achieve and maintain a state of control and to improve the capability of the process.
Statistical Quality Control	The application of statistical methods to the identification, prediction, measure, and correction of problems in quality control.
Stator	The portion of a rotating machine that contains the stationary parts of the magnetic circuit and their associated windings.
Steady State	Equilibrium mode distribution.
Step Change	Sudden change in a converter parameter. Typically used in referring to changes in output load or input line during converter testing.
Step Down Transformer	When the secondary has a lower voltage than the primary.
Step Index	A fiber construction where the core is one distinct index of refraction and the cladding a lower one causing the light to travel down a fiber by reflecting off the corecladding interface.
Step-index Fiber	An optical fiber, either multimode or single mode, in which the core refractive index is uniform throughout so that a sharp step in refractive index occurs at the core-to-cladding interface. It usually refers to a multimode fiber.
Stop Sentinel	The binary coded character used to determine the end of a message on a magnetic stripe credit card.
Storage	System memory.
Storage Temperature Range	Range of ambient temperatures over which a component can be stored safely (Also see Operating Temperature Range)
STP	Shielded Twisted Pair.2-Pair 150 ohm shielded cable.
Strain Relief	The technique for or act of removing or lessening the strain or stress on a joint, splice, or termination. SolderSleeve devices provide strain relief.
Strain Relief Clamp	A device used to give mechanical support for the contacts from the weight of a wire bundle or cable. May be referred to as cable clamp.
Strand	A single unit of a conductor.
Stranded Conductor	A conductor composed of more than one single strand. The strands in stranded conductors are usually twisted or braided together.
Strength Member	That part of a fiber-optic cable composed of Kevlar aramid yarn, steel strands, or fiberglass filaments that increase the tensile strength of the cable.
Strip	(1) To remove insulation from a wire or cable. (2) "Strip" terminals (or contacts) are produced in continuous lengths, and placed on reels, for application in automatic or semi-automatic machines.
Stripe	A continuous longitudinal or spiral color strip applied on the surface of a wire, cable, or tubing for identification.
Stripline	A multi-layer transmission line that consists of two ground planes, separated by two layers of dielectric material that sandwich between them a thin center conductor that has a rectangular cross section. The impedance of stripline is determined by the thickness and dielectric constant of the dielectric layers and the width of the center conductor.
Stud	A metal rod or pin (bolt) projecting from a piece, for the attachment and/or support of a second piece. The projecting end of the stud most commonly has screw threads, and the second piece is secured with a nut.
Stud Hole	The hole or slot in the tongue of a terminal, made to accommodate a screw, bolt, or stud of a given size.
Styrene-Butadiene	Copolymer synthetic rubber characterized by good electrical properties and moisture resistance. Ozone resistance, physical properties, and chemical resistance are generally improved by blending with other materials.
Subassembly	Two or more parts which form a portion of an assembly (or a unit replaceable as a whole), but having a part or parts which are individually replaceable.
Subminiaturization	The packaging of miniaturized parts, using unusual assembly techniques to increase volumetric efficiency.
Substrate	The physical material on, or within, which the elements of an integrated circuit are fabricated. Ceramic, plastic, and glass substrates satisfy the primary functions of mechanical support and insulation, but semiconductor and ferrite substrates may also provide useful electrical functions. See also wafer.
Subsystem	An interconnection combination of a set of related circuits, which form a logical subdivision of an equipment or operational system.
SUPER CHAMP	The AMP trademark for a stamped hand tool designed to crimp 22-10 insulated terminals. This tool also cuts and strips wire and shears 4/40 through 10/32 bolts.
Super Compact	A software package that analyzes and optimizes RF/microwave circuits using frequency domain analysis.
Superhigh Frequency	SHF - A Federal Communications Commission designation for the band from 3,000 to 30,000 MHz in the radio spectrum.
Supply Current	Rated output current of a given device. Power switch devices have been designed to support a continuous load (supply) current of 0.6A at ambient temperature.
Supply Voltage	Voltage level of the power switch input. Raychem power switch devices have been designed to operate using supply voltage levels from 3.0V to 5.5V.
Surface Area	The effective surface area of a typical wound core available to dissipate heat.
Surface Resistance	The ratio of the direct current applied to an insulation system to the current that passes across the surface of the system.
Surface-Mount Device	An electronic component, ranging from discrete passive components to VLSI chips, attached to the surface of a printed circuit board, either directly or through a surface-mount connector, rather than by means of holes in the board.
Surge	A transient variation in the current and/or potential at a point in the circuit.
SV	Space Vehicle.
Swedging	Another term for crimping.
Swing	A term used to describe how inductance responds to changes in current, ie a 2:1 swing corresponds to an inductor which exhibits two times more inductance at very low current than it does at its maximum rated current. This would also correspond to the core operating at 50% of initial permeability (50% saturation).
Swinging Inductors	A special type of inductor that exhibits high inductance at low MMF and moderate inductance at high MMF. There are two popular techniques for accomplishing this: placing a common winding on a high permeability core and a low permeability core, and placing a staggered gap into a high permeability core.
Switch	(1) A mechanical or electronic device used to make or break an electrical circuit. (2) An N-port device that directs energy from one port to another or interrupts the flow of energy. A switch can use mechanical, electromechanical or electronic switching elements. (3) A type of network hub. Provides higher bandwidth than shared hubs.
Switch Mode Power Supply	A power conversion technique that involves breaking the input power into pulses at a high frequency by switching it on and off and re-combining these pulses at the output stage. Using this technique, an unregulated input voltage can be converted to one or more regulated output voltages at relatively high efficiencies.
Switched Virtual Circuit	SVC - A virtual link, with variable end-points, established through an ATM network. With an SVC, the user defines the end-points when the call is initiated that are subsequently terminated at the end of the call. With a Permanent Virtual Circuit(PVC), the end-points are predefined by the network manager. A single virtual path may support multiple.
Switching Frequency	The rate at which the DC input to a switching regulator is switched on and off.
Switching Regulator	A circuit that is designed to regulate the output voltage, from a given input voltage, by using a closed control loop design. The most common switching regulator types involve a magnetic component, such as an inductor or transformer, that is used to store and transfer energy to the output by having the current switched on and off (Also see Boost Regulator and Buck Regulator)
Switching Time	The time required for the output of a switch to attain 90 percent of its steady-state level referenced to the 50 percent level of the command signal.
SWR	Standing Wave Ratio - The ratio between maximum and minimum current, or voltage, along a line. It is a measure of the mismatch between the load and the line, and is equal to 1 when the line impedance is perfectly matched to the load. (In that case the maximum and minimum are the same, as current and voltage do not vary along the line.) The perfect match would be referred to as a 1 to 1 ratio. Vswr is voltage standing wave ratio.
Symmetrical Transmission	Transmission in which a channel sends and receives data with the same signaling rate.
Synchronize	Make sure that the level or pulse is presented to the system, or subsystem, at the correct time.
Synchronizer	A computer storage device used to compensate for difference in rate of flow of information, or time of occurrence of events, when transmitting information from one device to another.
Synchronous	A device or system in which all events occur in a predetermined timed sequence. Usually all parts operate to a common clock. See also asynchronous.
Synchronous Generator	An alternator (ac generator); a synchronous alternating-current device which transforms mechanical power into electrical energy.
Synchronous Transmission	Transmission in which the data characters and bits are transmitted at a fixed rate with the transmitter and receiver synchronized.
System	An assembly of components united by some form of regulated interaction to function as an entity.
System Damage Voltage	Maximum voltage across a SiBar device at breakdown measured under a specified voltage rate of rise and current rate of rise.

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T

T Rise	Change in temperature of a terminal from a no-load condition to full-current load.
T1	Digital transmission facility operating with a nominal bandwidth of 1.544 Mbps. Also known as Digital Signal Level 1 (D1). Composed of 24 DS-0 channels in many cases. The T1 digital transmission system if the primary digital communication system in North America.
T2L	Transistor Transistor Logic. A popular bipolar logic family based on a multiple-emitter transistor. Compared to MOS logic, TTL is generally faster, although it uses more power and offers less packaging density. See also Schottky TTL. Also called TTL
T3	Digital transmision facility operating at 45 Mbps bandwidth. Composed of 28 DS-1 channels in many cases. Also known as DS-3.
T568A and B	The two standard wiring patterns for 8-position modular jacks.
Tab	Used to describe the flat blade portion of certain terminals (eg a FASTON* tab, a taper tab, a solder tab). Also, on strip terminals, is used to describe the projection which results when the point-of-shear is not flush with the terminal body (ie cutoff tab).
Tab-Lok Crimp	A type of crimp used on FASTON flag terminals whereby a tab on the wire barrel is inserted through a slot in the terminal. The crimping action flattens the tab between two lances, which in turn are locked over the tab.
Table	A collection of data in tabular form (usually in parallel rows or columns for ready reference), with each item being uniquely identified by some label or by its relative position. See also truth table.
Tactile Feedback	The feel or snap action of certain constructions of keyboards.
Tap (Network)	The means of connecting a piece of equipment to the transmission media of a network.
Tap Loss	In a fiber-optic coupler, the ratio of power at the tap port to the power at the input port.
Tap Port	In a coupler in which the splitting ratio between output ports is not equal, the output port containing the lesser power.
Tape Memory	A serial, bulk-storage, off-line memory medium consisting of metal, paper, or plastic tape coated with magnetic material. Information is stored as small magnetized spots, usually arranged in columns across the width of the tape, with each column representing a tape character. A read-write head is usually associated with each row of magnetized spots so that one column can be read or written at a time as the tape is moved relative to the head. Paper tape in which data is stored in form of punched holes, as in numerically controlled machinery and teletype equipment, is also considered tape memory.
Tape Wound Core	Cores made by rolling strips of alloy iron into a toroidal shape. The metal strips have a precisely controlled thickness which are coted with a very thin insulation material to prevent the metal in the layers to make contact with each other. The finished cores have an outside coating to protect the metal layers and they are offered in a variety of material mixes. Tape wound cores are capable of storing high amounts of energy and contain a high permeability. Their major disadvantage is that they are relatively expensive when compared to other core types (Also see Toroidal Inductor)
Tape Wound Cores	Cores made by rolling strips of alloy iron into a toroidal shape. The metal strips have a precisely controlled thickness, which are coated with a very thin insulating material to prevent the metal in the layers to make contact with each other. The finished cores have an outside coating to protect the metal layers and they are offered in a variety of material mixes. Tape wound cores are capable of storing high amounts of energy and contain a high permeability. Their major disadvantage is that they are relatively expensive when compared to other core types.
Tape Wrap	A term denoting a spirally or longitudinally applied tape material wrapped around insulated or uninsulated wire and used as a mechanical barrier.
Tape-Mounted	Screw-machine or pre-insulated terminals (or contacts) that are produced in loose-piece form and then inserted into plastic pockets in continuous lengths, and placed on reels, for application in automatic or semi automatic machines.
Taper Pin	A small conical shaped electrical contact that utilizes the Morse taper principle to effect a strong mechanical connection after being impacted into a receptacle of corresponding geometric form.
Target Area	A term used to indicate the relationship of the three axes (lateral, vertical, and axial) of terminal with the crimp tooling. The point at which all three axes coincide is called the target area.
TC	(1) Tinned copper; (2) Temperature Coefficient - A factor used to calculate the change in the characteristics of a substance, device, or circuit element with changes in its temperature. The values are usually expressed as a percentage per degree Celsius. Applies to the change in capacitance or resistance of any electronic part or element per degree change in temperature.
TCR	Temperature coefficient of resistance.
TDM	Time-division multiplexing.
TDMA	Time Division Multiple Access. (See also CDMA)
TDMA	Time division multiple access. A transmission in which a frequency band is split into a number of time slots so that several callers can share a single channel without interfering with each other. The term TDMA is commonly used to denote the IS -136 air interface standard, formerly known as D-AMPS.
TDOP	Time clock offset
Tear Test	A test to determine the tear strength of an insulating material. Usually includes exposure to given thermal conditions or a programmed series of conditions for prescribed periods of time.
Technischer Uberwachungs-Verin (TUV)	Organization approved for testing products to VDE standards. US-based companies often use TUV in place of VDE because they hae established facilities in the US.
Tee Coupler	A three-port optical coupler.
Telco	Short for telecommunications (or telephone company).
Telco Connector	Refers to a 25-pair (AMP CHAMP) connector.
Telecom Closet	Telecommunications closet. The area of the building that houses the termination of the horizontal cabling.May also contain LAN electronics. Also called wiring closet
Telecommunication	Any process that enables a correspondent to pass to one or more given correspondents (telegraphy or telephony), or possible correspondents (broadcasting), information of any nature delivered in any usable form (written or printed matter, fixed or moving, pictures, words, music, visible or audible signals, signals controlling the functioning of mechanisms, etc) by means of any electromagnetic system (electrical transmission by wire, radio transmission, optical transmission, etc, or a combination of such systems).
Telecommunications Transformers	Also referred to as broadband transformers, these are transformers specialized for connecting a piece of equipment to the phone line or telephone network. Its function is to isolate the equipment from the phone line, improve common mode noise rejection, and match different impedances.
Telecommuter	Person who performs work at home while linked to the office by means of a telecommunications-equipped computer system.
Telpak	A high-speed telephone or broadband service. Telpak has the wide band channels necessary for computer-to-computer communication and other special high-speed applications. There are presently four sizes of telpak available: Telpak A - Equivalent in capacity to 12-voice circuits.; Telpak B - Equivalent in capacity to 24-voice circuits.; Telpak C - Equivalent in capacity to 60-voice circuits.; Telpak D - Equivalent in capacity to 240-voice circuits.
Temperature Coefficient	TC - A factor used to calculate the change in the characteristics of a substance, device, or circuit element with changes in its temperature. The values are usually expressed as a percentage per degree Celsius. Applies to the change in capacitance or resistance of any electronic part or element per degree change in temperature.
Temperature Coefficient Of Inductance	(Tc of L)Is the value of inductance change as a function of temperature exposure, normally expressed in parts per million per degrees Celsius. This is a calculation comparing inductance at a reference temperature (25 degrees C, room ambient) to the extremes and other temperatures within operating range. Can be called Percent Delta L. or Temperature Stability: the lower the change the better for most applications.
Temperature Coefficient of Linear Expansion	The amount of change in any linear dimension of a solid arising from a change in temperature. Usually measured in microinches per inch per degree Celsius. When crimping two metals with dissimilar coefficients, ie, aluminum wire in a copper terminal wire barrel, special considerations must be included in the terminal design to prevent deterioration from "creep." See also creep.
Temperature Factor (TF)	The fractional change in initial permeability over a temperature range divided by the initial permeability.
Temperature Range	The ambient temperature range of the air (or other medium) surrounding a PolySwitch device under normal operating conditions.
Temperature Rating	The maximum temperature at which the insulating material may be used in continuous operation without loss of its basic properties. Usually time dependent.
Temperature Rise	(1) Change in temperature of a terminal from a no-load condition to full-current load. Also called T rise. (2) The increase in surface temperature of a component in air due to the power dissipation in the component. The power dissipation for an inductor includes both copper and core losses.
Tempest	A classified Department of Defense program to provide secure electronic equipment through extensive EMC techniques.
Tensile	The amount of axial load (longitudinal stress) required to break or pull the wire from the crimped barrel of a terminal, splice, or contact. Also called "pull test."
Tensile strength	The greatest longitudinal stress that a substance (union) can bear without tearing (pulling) apart. In crimped terminations: the greatest longitudinal stress that the termination can bear without the wire and terminal separating.
Tera	A prefix indicating 1012, a trillion, abbreviated "T."
Terahertz	A frequency of, or a frequency in the range of a trillion hertz. Abbreviated THz.
Terapin	A trillion pins.
Termal Conductivity	Given materials ability to conduct heat, which is the time rate for heat transfer (via conduction) across a unit material thickness of 1 meter and when the temperature differential of the two opposite faces is 1 degree K.
Terminal	An electrically conductive item designed to be attached to a circuit or device for convenience in making electrical connections.
Terminal area	The portion of a printed circuit - usually along the edge - used for making the input-output connections. Sometimes this term is used synonymously with pad. See also land, and pad.
Terminal Barrel	See barrel.
Terminal Strip	An insulated mounting for terminal connections. Terminal strips are available with threaded holes to accept threaded screws, or with threaded studs to accept fastening washers and nuts. If the terminal areas are separated by an insulating barrier, the terminal strips are called barrier blocks.
Termination	A one port component that terminates a transmission line.
Terminus	A part of a fiber-optic connector analagous to a contact.
Terpolymer	A resin formed by three separate monomers polymerized together.
Tesla	The MKSA (SI) unit for magnetic flux density, defined by Faraday"s Law. A Tesla represents a volt-second per square meter per turn. One Tesla is equal to 10,000 Gauss.
Test Frequency	Is the industry/military standard for testing a range of inductances. It is not intended as the application frequency. Expressed in megahertz (MHz) or kilohertz (KHz)
TETRA-CRIMP tools	Exclusive AMP designed tooling featuring a trapezoidal crimp configuration which will crimp PIDG and PLASTI-GRIP terminals and splices, as well as PIDG and PLASTI-GRIP FASTON receptacles all in the same tool. Includes hand tool, crimping dies, and applicators.
Thermal Compression Bond	The joining of metals by the combined effects of temperature and pressure.
Thermal Conductivity	Given materials ability to conduct heat, which is the time rate for heat transfer (via conduction) across a unit material thickness of 1 meter and when the temperature differential of the two opposite faces is 1 degree K.
Thermal Derating	The change in the hold current and trip current of a PolySwitch device that takes place as there is a change in the ambient temperature of the air (or other medium) surrounding the device. An increase in ambient temperature decreases the hold current (and the trip current). A decrease in ambient temperature increases the trip current (and the hold current).
Thermal Expansion	The fractional change in length (sometimes volume) of a material for a unit of change in temperature.
Thermal Gasket	Flexible pad or wafer with a very low thermal resistance that is put between a power module baseplate and heat sink to ensure high thermal conductivity across the junction
Thermal Joint Compound	A fluid or paste spread between the mating surfaces of a power device baseplate and a heat sink or system chassis.
Thermal noise	Noise resulting from thermally induced random fluctuation in current in the receiver"s load resistance.
Thermal Protection	Feature that shuts the converter down if the internal tempurature exceeds preset limits. Also called thermal shutdown.
Thermal Rating	The maximum and/or minimum temperature at which a material will perform its function without undue degradation.
Thermal Rating	The effect of heat or cold applied at such a rate that nonuniform thermal expansion or contraction occurs within a given material or combination of materials. In electrical terminations, the effect can cause inserts and other insulation material to pull away from the metal parts.
Thermal Resistance	The property of a material, device or system that impedes the flow of heat. The symbol for thermal impedance is Qxy , where x is the physical point from which heat flows and y is the physical point to which heat flows. Thermal impedance is defined as the temperature difference between two specified points or regions divided by the power dissipation under conditions of thermal equilibrium.
Thermal Resistivity	Measure of a material;s ability to impede the flow of heat. Typically given in degrees C T/W, where T is the material thickness and W is the power flowing through the material in watts.
Thermal Shock	The effect of heat or cold applied at such a rate that nonuniform thermal expansion or contraction occurs within a given material or combination of materials. The effect can cause inserts and other insulation materials to pull away from metal parts.
Thermal Shock Test	A test in which the resistance of a PolySwitch device at room temperature is measured before and after a temperature cycling treatment (e.g., cycled 10 times between Ð55¡C and +125¡C).
Thermal Timedelay Switch	An overcurrent-protective device containing a heater element and thermal delay.
Thermochromic Indicator	Special compound that changes color when the proper wetting temperature has been reached in the solder joint.
Thermoplastic	A material that softens (melts and flows) when heated and becomes firm when cooled. A type of plastic that can be remelted a number of times without any important change in properties. Nylon, GE’s Lexan, and PVC—examples of this type of plastic—are resilient after molding.
Thermoplastic Elastomer	TPE - A jacket material which has many of the characteristics of rubber, as well as excellent electrical, mechanical, and chemical properties.
Thermoset	A material that hardens or sets when heated and, once set, cannot be resoftened by heating. This application of heat is called “curing.”
Thermosetting Adhesive	A curing adhesive that requires heat to promote curing. This type of plastic will not soften when reheated. See Epoxy.
Thermosetting Plastic	A type of plastic in which an irreversible chemical reaction takes place while it is being molded under heat and pressure. This type of plastic cannot be reheated or softened. Phenolic and diallyl phthalate are examples of thermosetting plastics.
Thick Film	A film of material that was silk-screened onto a substrate.
Thick Film Circuit	A circuit fabricated by deposition of materials forming passive components and conductors to an approximate thickness 0.05 mils on a nonconducting substrate (generally alumina or beryllia).
Thicknet	IEEE 10BASE5.10 Mbps Ethernet on thick coaxial cable.
Thin Film	A film of material, ranging in thickness from a few hundred to a few thousand Angstroms, which is deposited by evaporation onto a substrate.
Thin Film Circuit	A circuit fabricated by deposition of materials in a vacuum to form passive components and conductors to a thickness of several hundred angstroms on an insulating substrate.
Thinnet	IEEE 10BASE2. 10 Mbps Ethernet on thin (RG58) coaxial cable.
Three-Terminal Regulator	Regulator packaged in a standard 3-terminal transistor package. These devices can be a switching type or a linear shunt or series regulator.
Throughput Loss	In a fiber-optic coupler, the ratio of power at the throughput port to the power at the input port.
Throughput Port	In a coupler in which the splitting ratio between output ports is not equal, the ouput port containing the greater power.
Time-Delay	A circuit that delays the transmission of an impulse a definite and desired period of time.
Time-Delay Relay	A relay in which the energizing or deenergizing of the coil precedes movement of the armature by an appreciable - and generally determinable - interval.
Time-Delay Switch	A switch having contacts which control a load circuit and are delayed from operating for a predetermined time interval.
Time-Division Multiplexing	A technique used in data communications technique for combining several lower speed channels into one transmission path at higher speed in which each low-speed channel is allotted a specific position based upon time in the signal stream.
Time-to-Trip	The time needed, from the onset of a fault current, to trip a PolySwitch device. For any particular type of PolySwitch device, trip time depends upon the size of the fault current and the ambient temperature. The higher the fault current and/or the higher the temperature, the shorter the trip time.
Timeshare	To use a device for two or more interleaved purposes.
Tinning	A hot dip process for the application of solder coating on conductors and terminals primarily for minimizing in-process oxidation and enhancing solderability.
TNC Series connector	A radio frequency connector covered by Military Specification. It has an impedance of 50 ohms and is designed to operate in the 0 to 11 GHz frequency range. Reliability is assured by a threaded coupling that can be safety wired to prevent accidental disconnect.
TO can	Transistor outline. A standard system for specifying the dimensions of a transistor package. Each different package is given a number: TO-5, TO-18, TO-52, etc.
Token ring	A networking protocol based on a token-passing ring.
Tolerance	The total amount by which a quantity is allowed to vary from nominal; thus, the tolerance is half the algebraic difference between the maximum and minimum limits.
Tone-Encoded Keyboard	A keyboard encoded in rows and columns designed to be the same as those used in telephones.
Toroid	A core that has a donut shaped surface. Toroidal cores are available in many magnetic core materials. Characteristics of toroidal inductors include self-shielding due to a closed magnetic path, efficient energy transfer, high coupling between windings, and early saturation. The toroidal core gives a maximum magnetic field within itself, with minimum magnetic flux leakage externally.
Toroidal Inductor	An inductor constructed by placing a winding(s) on a core that has a donut shaped surface. Toroidal cores are available in many magnetic core materials within the four basic types: Ferrite, Powdered iron, Alloy and High Flux, and Tape Wound. Characteristics of toroidal inductors include: self shielding (closed magnetic path), efficient energy transfer, high coupling between windings and early saturation.
Trace Capacitance	The capacitance between trace to reference plane
Traceability	The ability to trace the history, application, or location of an item and like items or activities by means of recorded identification. The lot number/manufacturing order (MO) number, or SMO number used to identify items or groups of items is traceable back to inspection and procurement records.
Track	The portion of a moving storage medium, such as a drum, tape, disc, or card, that contains the encoded data.
Tracking	For a multiple output converter the parameter that gives the change in one output voltage caused by a change in the voltage level or load on another output.
Tracking	The action of a high voltage current creating a leakage or fault path across the surface of insulation by steadily forming a carbonized thin line between electrodes.
Transfer molding	A method of molding thermosetting materials, in which the plastic is first softened by heat and pressure in a transfer chamber, and then forced into a closed mold for final curing.
Transformer	A passive device that changes voltage, current, or impedance to the required parameters. This is usually done by placing two or more windings around a soft magnetic core. Applying a voltage to the primary winding will produce a magnetic field in the core, and in turn induce a voltage in the secondary winding(s).
Transient	Spike or step change in a converter paramenter. Commonly used in describing input line and output load characteristics.
Transient Recovery Time	Time required for a converter output to return to within specified limits following a step change in output load current. Expressed as a percentage of rated value.
Transient Suppression	The use of special devices to minimize the effects of transients in electronic circuits. Transient suppression devices include the metal oxide varistor (MOV), semiconductor transient voltage suppressor (TVS) and gas tube.
Transients	Undesirable voltage and current surges that are usually caused by capacitive or inductive energy discharges in electrical circuits.
Transistance	An electronic characteristic exhibited in the form of voltage or current gain, or in the ability to control voltages or currents in a precise nonlinear manner. Transistors, diodes, and vacuum tubes are examples of components which show transistance.
Transistor	An active solid-state semiconductor device with three or more electrodes and capable of amplification, rectification, and switching. Important features are low power, small size, and long life. Two main types are bipolar and field effect.
Transition Time	The time required for a varactor or step recovery diode to change from the conducting to non-conducting state after reverse bias is applied, excluding the time required for charge to be conducted from the junction. It is normally measured from the 90 percent to 10 percent reverse current states. Transition time is also called "snap time."
Transmission Cable	Two or more transmission lines. If the structure is flat, it is sometimes called flat transmission cable to differentiate it from a round structure such as a jacketed group of coaxial cables. See also Transmission Line.
Transmission Line	A signal-carrying circuit with controlled electrical characteristics; used to transmit high-frequency or narrowpulse signals.
Transparent LAN Service	Two or more transmission lines. If the structure is flat, it is sometimes called flat transmission cable to differentiate it from a round structure such as a jacketed group of coaxial cables. See also Transmission Line.
TRAPATT	TRApped Plasma Avalanche Transit Time.
TRI	Telephony return interface.
Tri-State	Tri-State buffer is a buffer that can be either input or output.
Triac	A multilayer semiconductor device designed for ac power supply applications. It presents an open circuit between its two power terminals to ac until it is triggered on. It then has a low forward voltage drop like an SCR. The triggering pulse, applied to the triggering terminal, can be of either polarity during either half cycle of applied voltage. Planar triacs have been fabricated.
Triaxial Cable	A concentrically constructed cable, with a common axis, composed of a center connector, first shield, and second shield, all insulated from each other.
Trimming	The adjustment of resistor or capacitor values in thick or thin film circuits by pattern changes, irreversible thermally induced changes, or removal of portions of material by laser or abrasive techniques. Dynamic trim is unique to these technologies, and of great value to circuit design and manufacture.
Trip	Switching of a PolySwitch device from a low resistance to a high resistance. In its low-resistance state, the device permits normal currents to flow in a circuit. Occurrence of a fault drives the device to its high-resistance (or "tripped") state, and this reduces the current in the circuit to a low level.
Trip Current	The smallest steady state current that, if passed through a PolySwitch device, will cause the device to trip, under specified conditions.
Trip Cycle	The tripping and resetting of a PolySwitch device under specified conditions.
Trip Cycle Life	The number of trip cycles that a PolySwitch device will undergo without failure, with failure being defined in a specified way.
Trip Time	The time needed, from the onset of a fault current, to trip a PolySwitch device. For any particular type of PolySwitch device, trip time depends upon the size of the fault current and the ambient temperature. The higher the fault current and/or the higher the temperature, the shorter the trip time.
TRK	Track. Direction of travel relative to a ground position (same as Course Over Ground)
TRN	Turn. The degrees which must be added to or subtracted from the current heading to reach the course to the intended waypoint.
Truth Table	A table that defines a logic function by listing all combinations of input values, and indicating for each combination the true output values.
TTFF	Time to First Fix
TTL	Transistor-transistor logic. A popular bipolar logic family based on a multiple-emitter transistor. Compared to MOS logic, TTL is generally faster, although it uses more power and offers less packaging density. See also Schottky TTL. Also called T2L
TtT	The time needed, from the onset of a fault current, to trip a PolySwitch device. For any particular type of PolySwitch device, trip time depends upon the size of the fault current and the ambient temperature. The higher the fault current and/or the higher the temperature, the shorter the trip time.
Tuning Monotonicity	The degree to which the sign of the slope of the tuning response versus stimulus curve of a device does not change.
Tunnel Diode	A heavily doped p-n diode in which electron tunneling from the conduction band in the n-type material to the valence band in the p-type region produces a region of negative resistance. Tunnel diodes may be used as oscillators, amplifiers or detectors (M/A-COM does not manufacture tunnel diodes).
Turn Ratio	The ratio of the primary voltage (or turns) to the secondary voltage (or turns)
Twisted Pair	Cable consisting of two 18 to 24 AWG (American Wire Gauge) solid copper strands twisted around each other. The twisting provides a measure of protection from electromagnetic and radio-frequency interference.
Twisted Pair Cable	Cable made from pairs of wires which have been twisted together.
Two-Piece Connector	A board-to-board connector in which part of the connector is attached to each board.
Two-Piece Contact	(contact) See contact, two-piece.
Two-Tone Third-Order Intermodulation Distortion	The intermodulation distortion products produced by a component or system when two distinct signals at frequencies f1 and f2 are incident on the device. The third order products are defined as 2f1-f2 and 2f2 - f1. These products fall very near the original frequencies and are difficult or impossible to remove by filtering, so they are most troublesome to the operation of the system or component.

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U

U-NII	Unlicensed national information infrastructure spectrum, 5.8-GHz.
UADSL	Universal ADSL.
UDP	User datagram protocol.
UG	Used to describe coaxial connectors that are made to a Government Specification.
UHF	Ultra High Frequency - A Federal Communications Commission designation for the band from 300 to 3000 MHz on the radio spectrum. In television, channels 14 to 83, or 470 to 890 MHz.
UL	Underwriters" Laboratories, Inc. An independent laboratory that tests equipment to determine whether it meets certain safety standards when properly used.
Ultrahigh Frequency	UHF - A Federal Communications Commission designation for the band from 300 to 3000 MHz on the radio spectrum. In television, channels 14 to 83, or 470 to 890 MHz.
Ultrasonic Bond	A joining of materials achieved by the scrubbing action and energy transfer of a tool vibrating at an ultrasonic frequency. Attaching leads to pads on silicon devices, and achieving bonds between dissimilar metals are two common applications of this process. See also ultrasonic welding.
Ultrasonic Welding	Process using vibratory mechanical pressure at ultrasonic frequencies (20 to 40 kHz) to provide heat for welding some types of thermoplastics. See also ultrasonic bond.
Ultraviolet Curing	Process of accomplishing complete cross-linkage of a polymer coating or other product using ultraviolet light on the work piece.
Ultraviolet Degradation	The degradation caused by long-time exposure of a material to sunlight or other ultraviolet rays.
Umbilical Connector	Used to connect ground support cables to a rocket or missile, and is then disconnected from the missile at the time of launching.
UMTS	Universal mobile telecommunications system. The name of the third-generation mobile phone standard promoted by ETSI for use in Europe.
Uncertainty	The degree to which a parameter or characteristic cannot be specifically determined.
Undershoot	Transient change in a converter output voltage that does not meet the lower limit of the voltage accuracy specificiation. Typically occurs at converter turn on/off or with some step change in output load or input line. Also see Voltage Accuracy.
Undervoltage lockout	Design feature that helps regulate the quality of the output voltage by turning the device OFF in response to supply voltages that fall below its UVLO level. Raychem power switches have a nominal UVLO threshold of 2.5V.
Underwriters Laboratory	UL - Independent organization that conducts safety testing of products to established standards.
Uninterruptible Power Supply	UPS - Power supply that will continue to operate after the loss of AC input power.
UNIX	A popular operating system originally developed by Bell Labs.
Upconverter (Mixer)	A mixer whose desired output signal, called the RF signal, is the sum of the incident baseband (sometimes called the IF) and LO signals.
UPS	Uninterruptible Power Supply - Power supply that will continue to operate after the loss of AC input power.
UTC	Coordinated Universal Time.
UTM	Universal Transverse Mercator. An almost worldwide coordinate projection system using north and east distance measurements from reference point(s). UTM is the primary coordinate system used on U.S. Geological Survey topographic maps.
UTP	Unshielded twisted pair cable. Cable made from pairs of wires which have been twisted together.
UV	Ultraviolet.
UVLO	Design feature that helps regulate the quality of the output voltage by turning the device OFF in response to supply voltages that fall below its UVLO level. Raychem power switches have a nominal UVLO threshold of 2.5V.

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V

Vac	Volts, alternating current.
Vacuum Evaporation	A process for generating thin films, in which the film material is vaporized and the vapor deposits itself, through openings in a mask, onto a substrate.
Varactor	A p-n junction diode that is designed to act as a voltage controlled capacitance when it is operated under reverse bias
Varactor-tuned Oscillator	An oscillator whose frequency is a function of an externally generated voltage control signal.
Variable	A quantity that can assume any of a given set of values.
VCC	Voltage collector.
VCO	Voltage controlled oscillator - An oscillator whose frequency is a function of an externally generated voltage control signal.
Vdc	Volts, direct current.
VDE	Verband Deutscher Elektrontechniker - German organization that sets standards for product safety and noise emissions and test and certifies products to those standards.
VDOP	Vertical DOP.
VDSL	Very high bit-rate subscriber line.
Vector	A mathematical representation that has both magnitude and direction.
Vector Modulator	A modulator that modulates both amplitude and phase.
Velocity of Propagation	The ratio of the speed of a radio frequency wave within a cable or dielectric as compared with the same wave in free space.
Verband Deutscher Elektrontechniker	VDE - German organization that sets standards for product safety and noise emissions and test and certifies products to those standards.
Very High Frequency	VHF - A Federal Communications Commission designation for the band from 30 to 300 MHz on the radio spectrum.
Very-large-scale Integration	VLSI. An IC that in complexity contains over 1000 gates or their equivalent.
VHF	Very High Frequency. A Federal Communications Commission designation for the band from 30 to 300 MHz on the radio spectrum.
VHSIC	Very high speed integrated circuit. A Department of Defense program to develop exceptionally fast ICs.
Vias	Used to connect traces between two or more layers
Vibration	(1)A continuously reversing change in the magnitude of a force. (2)A mechanical motion or oscillation about a given point of equilibrium.
Video	The frequency spectrum that corresponds to that of a signal to be displayed in a television or radar system. The video bandwidth is generally considered to extend from DC to several megahertz.
Video Impedance	The video impedance of a detector diode is the low frequency impedance looking into the diode from the video amplifier. The symbol for video impedance is RV. It is essentially the (AC) slope of the diode at the bias level set up by external bias of the RF signal. This impedance is affected by the DC current flowing in the diode. It is normally specified at a small (i.e., 1 - 100 microamperes) current and can range from 500 ohms to megohms. Some ZBD"s are used without bias so RV is specified at zero bias. The video impedance can affect the pulse fidelity of a video detector since the RC time constant depends on RV and the bypass capacitor of the detector circuit.
Vinyl	A form of plastic used as insulation, which has high dielectric strength and low water absorption.
Viscosity	The measure of the resistance of a fluid to flow (either through a specific orifice or in a rotational viscometer). The absolute unit of viscosity measurement is the poise (or centipoise). Kinematic viscosity is expressed in strokes.
VLSI	Very Large Scale Integration - An IC that in complexity contains over 1000 gates or their equivalent.
Vmax	The highest voltage that can safely be dropped across a PolySwitch device in its tripped state under specified fault conditions.
VMG	Velocity Made Good. The rate of closure to a destination based upon your current speed and course.
VOD	Video On Demand .
VoDSL	Voice Over Digital Subscriber Line.
Voice-frequency	VF - Any frequency within that part of the audio-frequency range essential to speech transmission of commercial quality (ie 300 to 3400 Hz). Also referred to as telephone frequency.
VoIP	Voice over Internet Protocol.
Volatile Memory	A computer storage medium which is incapable of retaining information without continuous power dissipation.
volt	Abbreviated V. The unit of measurement of electromotive force. It is equivalent to the force required to produce a current of 1 ampere through a resistance of 1 ohm.
Volt Microsecond Constant	The product of the voltage applied across the winding and the time for the magnetizing current to reach 1.5 times the linear extrapolation of the current waveform. This constant is a measure of the entergy handling capability of a transformer or inductor. It is dependent upon the core area, core material (including the saturation flux density of the core), the number of turns of the winding and tile duty cycle of the applied pulse.
Volt-Ampere	VA - In an a.c. circuit, a measure of apparent power, given by: VA-EI, where E is the potential in volts; I is the curernt in amperes; and VA is apparent power in volt-amperes
Volt-Microsecond Constant	The product of the voltage applied across the winding and the time for the magnetizing current to reach 1.5 times the linear extrapolation of the current waveform. This constant is a measure of the energy handling capability of a transformer or inductor. It is dependent upon the core area, core material, number of turns, and the duty cycle of the applied pulse.
Voltage	Symbol E. The term most often used in place of electromotive force, potential, potential difference, or voltage drop to designate the electric pressure that exists between two points and that is capable of producing a current when a closed circuit is connected between the two points. Voltage is measured in volts, millivolts, microvolts, and kilovolts. The terms electromotive force, potential, potential difference, and voltage drop are all often called voltage.
Voltage Balance	For a multiple output converter, the percentage difference in voltage level of two outputs with opposite polarities and equal nominal values.
Voltage Breakdown	The voltage necessary to cause insulation failure.
Voltage Controlled Oscillator	An oscillator whose frequency is a function of an externally generated voltage control signal.
Voltage Drop	The voltage developed across a component or conductor by the flow of current through the resistance or impedance of that component or conductor. Often simply called voltage. Also called "drop." The voltage across a resistor is usually called IR drop, while that in a conductor is usually called resistance drop.
Voltage Rating	The voltage that may be continuously applied to wire.
Voltage Regulator	A circuit capable of generating from a varying input voltage a constant output voltage to a varying load current.
Voltage Standing Wave Ratio	VSWR - A measure of the uniformity of impedance along a transmission line, or the quality of the impedance match between a line and the source or load.
Voltage Tuned Filter	VTF - An electronically tunable, reactive circuit intended to pass or block portions of the electromagnetic spectrum, controlled by an externally generated voltage signal.
Volume Resistivity	The ability of a core to resist the flow of electrical current either through the bulk of the material or on its surface. The unit of the volume resistivity is Ohm-cm. Core volume resistivity becomes an issue in inductor designs where the leads/terminals come in contact with the core material. This type includes axial and radial inductors that have leads epoxied into the core. As for core materials, high permeability ferrites present the most concern as their volume resistivity is typically the lowest. Under certain conditions, a low resistive path can be realized between two inductor terminals if they are in contact with a low resistivity core. The inductor, under these conditions, will lose its higher impedance characteristics. Reciprocal of conductivity.
VPN	Virtual Private Network
VSAT	Very small aperture terminal.
VSWR	Voltage Standing Wave Ratio - A measure of the uniformity of impedance along a transmission line, or the quality of the impedance match between a line and the source or load.
VTF	Voltage Tuned Filter - An electronically tunable, reactive circuit intended to pass or block portions of the electromagnetic spectrum, controlled by an externally generated voltage signal.
VTG	An NMEA message.
Vulcanization	A chemical reaction in which the physical properties of an elastomer are changed by reacting it with sulfur or other cross-linking agents.
VW-1	A rating determined by the Underwriters’ Laboratories’ (UL) optional Vertical Wire Flame Test—the most difficult flame test for tubing. Tubings with a VW-1 rating are highly flame-retardant. Formerly designated FR-1.

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W

W crimp	Used on SOLISTRAND* terminals. A confined type of crimp that makes two longitudinal indentations which form a "W" cross section.
WAAS	Wide Area Augmentation Signal
Wafer	A thin, right cylindrical section slice of a semiconductor ingot or boule, from which discrete semiconductors or integrated circuits are manufactured. For RF/microwave devices, a wafer is typically 4 - 6 inches or 100 - 200 mm in diameter, and from 0.005 to 0.030 inches thick. See also substrate.
WAG	Wireless Assisted-GPS
Wall Thickness	The thickness of the applied insulation or jacket.
WAN	Wide Area Network- A network which encompasses interconnectivity between devices over a wide geographic area.
Warmup Drift	Change in the output voltage of a converter over a specified period of time. All other operating parameters (load, line, etc.) are assumed to be held constant. Often specified as starting after a warm up period.
Warmup Time	Time measured from the application of power to an operable system (or device) to the instant when it is capable of functioning in its intended manner.
Warp	Dimensional change in a molded, extruded, formed, or fabricated plastic part after processing.
Water Absorption Test	A method to determine the water uptake of a material. It is time and temperature dependent.
Water Blocking	The sticking together of insulated wires; usually caused by heat.
Watt	The unit for power, abbreviated as "W," equal to 1 joule per second. The practical unit of electric power. In a dc circuit, the power in watts is equal to voltage multiplied by current. In an ac circuit, the true power in watts is effective voltage multiplied by effective current, then multiplied by the circuit power factor. There are 746 watts in 1 horsepower.
Wattage Rating	A rating expressing the maximum power that a device can safely handle continuously.
Wave	A disturbance that is a function of time, space or both.
Wave Soldering	An automatic soldering method whereby the molten solder is pumped from a reservoir through a spout to form a head or wave. The board is then passed over the wave by a conveyor.
Waveform	The geometric shape of one period of an electric signal when it is plotted or displayed versus time or some other variable.
Waveguide	A system of material boundaries that direct electromagnetic energy waves. There are many different waveguide configurations, the most popular of which is constructed from hollow rectangular, elliptical or circular cross sections of metal. Some waveguides are filled with materials whose dielectric constants are higher than that of air, such as Teflon". Waveguides can also be implemented on the surface of a printed circuit board, as is the case for coplanar waveguide.
Wavelength	The physical distance between two points of identical phase on consecutive cycles of a wave. The symbol for wavelength is lambda, "l". Wavelength is related to frequency according to the equation l=c/f, where c is the speed of light (3*108 m/s) f is frequency in Hz.
WBI	Web-based Intranets
WCDMA	Wideband code division multiple access. Wideband CDMA, developed by Ericsson and others, provides higher data rates than present CDMA systems, and has been selected for the third generation of mobile telephone systems in Europe, Japan and the United States.
Weber	The practical unit of magnetic flux. It is the amount of magnetic flux, which, when linked at a uniform rate with a single turn electric circuit during an interval of one second, will induce an electromotive force of one volt.
Wedge Bond	A metal to metal lead bond formed with a wedge-shaped tool. The bond itself may be a cold weld, an ultrasonic or a thermal compression bond.
Welded Circuit	A circuit made up of electronic parts which have their leads interconnected by welding techniques.
Wetting	The formation of a relatively uniform, smooth, unbroken, and adherent film of solder to a base metal. Also, the free flow of solder alloy, with proper application of heat and flux, on a metallic surface to produce an adherent bond.
WGS84	World Geodetic Reference 1984
White Noise	Noise with constant energy per unit bandwidth that is independent of the central frequency.
Wicking	Capillary absorption of liquid (including water) along the fibers of the base material. The flow of solder along the strands and under the insulation of stranded lead wire.
Wideband	A loosely used term that indicates a large bandwidth to center frequency ratio. A system is considered to be wideband if this ratio is greater than approximately 10 percent.
Wilkinson Splitter	A transmission line structure that splits power incident on the input port into two or more output ports. In most implementations, the power is divided equally. A Wilkinson splitter can also be used to combine two or more signals.
Winchester Disk	A type of hard disk drive in which the read/write head is held a few millionths of an inch above the disk whenever the disk is spinning.
Winding Factor (K)	The ratio of the total area of copper wire inside the center hole of a toroid to the window area of the toroid.
Window Area (Wa)	The area in and around a magnetic core which can be used for the placement of windings.
Wiping Action	The action which occurs when contacts are mated with a sliding motion. Wiping has the effect of removing small amounts of contamination from the contact surfaces, thus establishing better conductivity. See also contact wipe.
Wire	A single bare or insulated metallic conductor having solid, stranded, or tinsel construction, designed to carry current in an electric circuit.
Wire Barrel	The portion(s) of a terminal, splice, or contact that is crimped. When designed to receive the conductor, it is called the wire barrel. When designed to support or grip the insulation, it is called the insulation barrel. Wire and/or insulation barrels may be either "open" or "closed" in design. Closed barrels resemble a hollow cylinder into which the wire must be inserted. Open barrels are formed into an open "U" and are common to most strip terminals manufactured by AMP Incorporated.
Wire Bonding	The very low resistance fusion of a conductive wire to a metallized area of a semiconductor die. For most RF/microwave semiconductors, the wire and the topmost layer of metal on the semiconductor die are very pure gold (Au).
Wire Crimp	The final configuration of a terminal barrel after the necessary compression forces have been applied to cause a functional union between the terminal barrel and wire.
Wire Dress	The orderly arrangement of wires and laced harnesses.
Wire Nut	A form of closed end splice, that is screwed on instead of being crimped.
Wire Size	See American Wire Gauge, and circular mil area.
wire stop	A stop at the end of a terminal wire barrel to prevent wire from passing completely through the barrel in such a way as to interfere with the function of the contact.
Wire Wrap	Trademark of the Gardner-Denver Corp for a wrap-type termination. See also wrap type.
Wiring closet	Telecommunications closet. The area of the building that houses the termination of the horizontal cabling.May also contain LAN electronics.
Withstanding Voltage	The test voltage an electrical connector can withstand for one minute without showing evidence of electrical breakdown when the voltage is applied between conductors and grounding devices of the connectors in various combinations. Also see Breakdown Voltage and Isolation.
WLAN	Wireless local area network
WLL	Wireless local loop.

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X

X	Letter symbol used to represent reactance in ohms.
X-Axis	The abscissa or horizontal axis in a cartesian plane.

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Y

Y	The ratio of current to voltage, the reciprocal of impedance. The unit of admittance is the siemens (S). Admittance is typically abbreviated as "y" or "Y."
Y-Axis	The ordinate or vertical axis in a cartesian plane.
y-Parameter	The set of parameters for a two port device that relates the input and output currents to the input and output voltages.
Yield	The ratio of usable components, at the end of a manufacturing process, to the number of components initially submitted for processing.

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Z

Z	Letter symbol used to represent impedance in ohms.
z-Parameter	The set of parameters for a two port device that relates the input and output voltages to the input and output currents.
z0	The characteristic impedance of a device or system.
Zener Diode	A diode that maintains a relatively constant voltage when the reverse voltage across it is increased passed a specific point, called the zener voltage.
Zero Voltage Switch	A circuit designed to switch "on" at the moment the ac supply voltage crosses zero. This technique minimizes the radio frequency interference generated at switch closure.
Zero Suppression	The elimination of nonsignificant zeros in a numeral.
ZIF	Zero Insertion Force - A component designed to eliminate the insertion and withdrawal forces during engaging and separating.
Zone Cabling	An architectural concept which splits the horizontal cabling into two sections. Eliminates the need to replace the entire horizontal cable in moves, adds and changes.

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