Glossary

AI-1

APPENDIX I

GLOSSARY

ACCEPTOR IMPURITY—An impurity which, when added to a semiconductor, accepts one electron

from a neighboring atom and creates a hole in the lattice structure of the crystal. Also called

TRIVALENT impurities.

ALLOYED JUNCTION—A junction formed by recrystallization of a molten region of P-type material

on an N-type substrate, or vice versa.

ALPHA—The emitter-to-collector current gain in a common-base circuit.

AMPLIFICATION—The ratio of output magnitude to input magnitude in a device that is intended to

produce an output that is an enlarged reproduction of its input.

AMPLIFICATION FACTOR—The voltage of an amplifier with no load on the output.

AMPLIFIER—The device that provides amplification (the increase in current, voltage, or power of a

signal) without appreciably altering the original signal.

AMPLITUDE DISTORTION—Distortion that is present in an amplifier when the amplitude of the

output signal fails to follow exactly any increase or decrease in the amplitude of the input signal.

ANODE—A positive electrode of an electrochemical device (such as a primary or secondary electric

cell) toward which the negative ions are drawn.

AVALANCHE EFFECT—A reverse breakdown effect in diodes that occurs at reverse voltage beyond 5

volts. The released electrons are accelerated by the electric field, which results in a release of more

electrons in a chain or "avalanche" effect.

BASE—The element in a transistor that controls the flow of current carriers.

BETA—The ratio of a change in collector current to a corresponding change in base current, when the

collector voltage is constant in a common-emitter circuit.

BREAKDOWN—The phenomenon occurring in a reverse-biased semiconductor diode. The start of the

phenomenon is observed as a transition from a high dynamic resistance to one of substantially lower

dynamic resistance. This is done to boost the reverse current.

CAPACITOR FILTER—This filter is used on extremely high-voltage, low current power supplies and

also where the ripple frequency is not critical.

CATHODE—The negative terminal of a forward-biased semiconductor diode that is the source of the

electrons.

CHOKE—An inductor used to impede the flow of pulsating dc or ac by means of self-inductance.

CLASS A AMPLIFIER OPERATION—The amplifier is biased so that variations in input signal

polarities occur within the limits of cutoff and saturation.

AI-2

CLASS AB AMPLIFIER OPERATION—The amplifier is biased so that collector current is cut off for

a portion of the alternation of the input signal.

CLASS B AMPLIFIER OPERATION—The amplifier is biased so that collector current is cut off for

one-half of the input signal.

CLASS C AMPLIFIER OPERATION—The amplifier is biased so that collector current is cut off for

more than one-half of the input signal.

COLLECTOR—The element in a transistor which collects the current carriers.

COMMON BASE—A transistor circuit in which the base electrode is the common element to both input

and output circuits.

COMMON COLLECTOR—A transistor circuit configuration in which the collector is the common

element to the input circuit and to the output circuit.

COMMON EMITTER—Circuit configuration in which the emitter is the element common to both the

input and the output circuit.

CONDUCTION BAND—A partially filled energy band in which electrons can move freely.

COVALENT BOND—A type of linkage between atoms.

CURRENT REGULATOR—A circuit that provides a constant current output.

DEGENERATION—The process whereby a part of the output signal of an amplifying device is returned

to its input circuit in such a manner that it tends to cancel part of the input.

DEPLETION REGION—The region in a semiconductor where essentially all free electrons and holes

have been swept out by the electrostatic field that exists there.

DIODE—A two element solid-state device made of either germanium or silicon. It is primarily used as a

switching device.

DONOR—An impurity that can make a semiconductor material an N-type by donating extra "free"

electrons to the conduction band.

DONOR IMPURITY—See PENTAVALENT IMPURITY.

DOPING—The process of adding impurities to semiconductor crystals to increase the number of free

charges that can be moved by an external, applied voltage. Doping produces an N-type or P-type

material.

DUAL-GATE MOSFET—A two-gate MOSFET in which either gate can control the conductor

independently, a fact which makes this MOSFET very versatile.

EFFICIENCY—The ratio of output-signal power compared to the total input power.

EMITTER—The element in a transistor that emits current carriers (electrons or holes).

EXTRINSIC—A semiconductor in which impurities have been added to create certain charge carrier

concentrations.

AI-3

FIELD-EFFECT TRANSISTOR (FET)— A transistor consisting of a source, a gate, and a drain.

Current flow is controlled by the transverse electric field under the gate.

FIDELITY-—The faithful reproduction of a signal. The accuracy with which a system reproduces a

signal at its output that faithfully maintains the essential characteristics of the input signal.

FIXED BIAS—A constant value of bias voltage.

FORBIDDEN BAND—The energy band in an atom lying between the conduction band and the valence

band. Electrons are never found in the forbidden band but may travel back and forth through it. The

forbidden band determines whether a solid material will act as a conductor, a semiconductor, or an

insulator.

FORWARD BIAS—An external voltage that is applied to a PN junction in the conducting direction so

that the junction offers only minimum resistance to the flow of current. Conduction is by majority

current carriers (holes in P-type material; electrons in N-type material).

FREE CHARGES—Those electrons that can be moved by an externally applied voltage.

FULL-WAVE RECTIFIER—A circuit that uses both positive and negative alternations in an

alternating current to produce direct current.

FULL-WAVE VOLTAGE DOUBLER—Consists of two full-wave voltage rectifiers and is used to

reduce the output ripple frequency.

FUSED-ALLOY JUNCTION—See ALLOYED-JUNCTION.

GALENA—A crystalline form of lead sulfide used in early radio receivers.

GAMMA—The emitter-to-base current ratio in a common-collector configuration.

GERMANIUM—A grayish-white metal having semiconductor properties.

GROWN JUNCTION—A method of mixing P-type and N-type impurities into a single crystal while the

crystal is being grown.

HALF-WAVE RECTIFIER—A rectifier using only one-half of each cycle to change ac to pulsating dc.

HALF-WAVE VOLTAGE DOUBLER—Consists of two half-wave voltage rectifiers.

HOLE FLOW—In the valence band, a process of conduction in which electrons move into holes,

thereby creating other holes that appear to move toward a negative potential. (The movement of

holes is opposite the movement of electrons.)

HYBRID CIRCUIT—A circuit where passive components (resistors, capacitors) are deposited onto a

substrate made of glass, ceramic, or other insulating material. Then the active components (diodes,

transistors) are attached to the substrate and connected to the passive components on the substrate

with a very fine wire.

IGFET—Any field-effect transistor that has an insulated gate.

INDUCED CHANNEL MOSFET—A MOSFET in which there is no actual channel between the source

and the drain. This MOSFET is constructed by making the channel the same type of material as the

substrate.

AI-4

INDUCTANCE—The properties of a circuit that tend to oppose any change in current flow.

INTEGRATED CIRCUIT—A circuit in which many elements are fabricated and interconnected by a

single process (into a single chip), as opposed to a "nonintegrated" circuit in which the transistors,

diodes, resistors, and other components are fabricated separately and then assembled.

JUNCTION DIODE—A two-terminal device containing a single crystal of semiconducting material,

which ranges from P-type at one terminal to N-type at the other.

JUNCTION TRANSISTOR—A bipolar transistor constructed from interacting PN junctions. The term

is used to distinguish junction transistors from other types such as field-effect and point-contact.

LC CAPACITOR-INPUT FILTER—This is the most common type of filter. It is used in a power

supply where output current is low and load current is relatively constant.

LC CHOKE-INPUT FILTER—This filter is used in power supplies where voltage regulation is

important and where the output current is relatively high and subject to varying load conditions.

LIGHT-EMITTING DIODE (LED)— A PN junction diode that emits visible light when it is forward

biased. Depending on the material used to make the diode, the light may be red, green or amber.

LINEAR—Having an output that varies in direct proportion to the input.

MAJORITY CARRIERS—The mobile charge carriers (holes or electrons) that are predominate in a

semiconductor material; for example, electrons in an N-type region.

METAL-OXIDE SEMICONDUCTOR FIELD-EFFECT TRANSISTOR—See MOSFET.

METALLIC RECTIFIER—Also known as a DRY-DISC RECTIFIER. A metal to semiconductor

large-area contact device in which a semiconductor is sandwiched between two metal plates. This

asymmetrical construction permits current to flow more readily in one direction than the other.

MICROELECTRONICS—The solid-state concept of electronics in which compact semiconductor

materials are designed to function as an entire circuit or subassembly rather than as circuit

components.

MINORITY CARRIERS—Either electrons or holes, whichever is the less dominant carrier in a

semiconductor device. In P-type semiconductors, electrons are the minority carriers; in N-type

semiconductors, the holes are the minority carriers.

MINORITY CURRENT—A very small current that passes through the base-to-collector junction when

this junction is reverse biased.

MODULAR CIRCUITRY—A technique where printed circuit boards are stacked and connected

together to form a module.

MONOLITHIC CIRCUIT—A circuit where all elements (resistors, transistors, etc.) associated with the

circuit are fabricated inseparably within a continuous piece of material (called the substrate), usually

silicon.

METAL-OXIDE SEMICONDUCTOR FIELD-EFFECT TRANSISTOR—See MOSFET.

AI-5

MOSFET—A semiconductor device that contains diffused source and drain regions on either side of a P-

or N-channel area. Also contains a gate insulated from the channel area by silicon-oxide. Operates in

either the depletion or the enhancement mode.

Mu/G178/G40/G81/G74/G79/G76/G86/G75/G3/G86/G83/G72/G79/G79/G76/G81/G74/G3/G73/G82/G85/G3/G87/G75/G72/G3/G42/G85/G72/G72/G78/G3/G79/G72/G87/G87/G72/G85/G3 /G17

NEGATIVE TEMPERATURE COEFFICIENT—A characteristic of a semiconductor material, such

as silver sulfide, in which resistance to electrical current flow decreases as temperature increases.

NONLINEAR—Having an output that does not rise or fall directly with the input.

NPN—An NPN transistor is formed by introducing a thin region of P-type material between two regions

of N-type material.

OPTICAL COUPLER—A coupler composed of an LED and a photodiode and contained in a

light-conducting medium. Suitable for frequencies in the low-megahertz range.

OPTOELECTRONIC DEVICES—Devices that either produce or use light in their operation.

OVERDRIVEN—When the input signal amplitude is increased to the point that the transistor goes into

saturation and cutoff.

PENTAVALENT IMPURITY—A type of impurity which contains five valence electrons and donates

one electron to the doped material. Also called DONOR IMPURITY.

PHOTOCELL—A light-controlled variable resistor that has a light-to-dark resistance ratio of 1:1000.

Used in various types of control and timing circuits.

PHOTODIODE—A light-controlled variable resistor. Current flow increases when the PN junction is

exposed to an external light source

PHOTOTRANSISTOR—An optoelectronic device that conducts current when exposed to light.

Produces more current and is much more sensitive to light than the photodiode.

PHOTOVOLTAIC CELL (SOLAR CELL)— A device that acts much like a battery when exposed to

light and converts light energy into electrical energy.

POINT-CONTACT TRANSISTOR—A semiconductor diode that can work with and amplify the

ultrahigh frequencies used in radar.

POSITIVE TEMPERATURE COEFFICIENT—The characteristic of a conductor in which the

resistance increases as temperature increases.

POWER SUPPLY—A unit that supplies electrical power to another unit. It changes ac to dc and

maintains a constant voltage output within limits.

PRINTED CIRCUIT BOARD—A flat insulating surface upon which printed wiring and miniaturized

components are connected in a predetermined design and attached to a common base.

QUANTUM-MECHANICAL TUNNELING—When an electron is able to cross a PN junction because

of tunnel effect.

QUIESCENCE—The operating condition of a circuit when no input signal is being applied to the

circuit.

AI-6

RC FILTER—This filter is used in applications where load current is low and constant, and voltage

regulation is not necessary.

RECTIFIER—A device which, by its conduction characteristics, converts alternating current to a

pulsating direct current.

REGULATOR—The section in a basic power supply that maintains the output of the power supply at a

constant level in spite of large changes in load current or in input line voltage.

REVERSE BIAS—When an external voltage is applied to a PN junction and the junction offers a high

resistance to current flow.

RIPPLE FREQUENCY—The frequency of the ripple current. In a full-wave rectifier, it is twice the

input-line frequency.

RIPPLE VOLTAGE—The alternating component of unidirectional voltage. (This component is small

compared to the direct component.)

SELENIUM—A chemical element which has rectification and light-sensitive properties that make it

widely used as a semiconductor material.

SERIES VOLTAGE REGULATOR—A regulator with a regulating device that is in series with the

load resistance.

SHUNT VOLTAGE REGULATOR—A regulator whose regulating device is in parallel with the load

resistance.

SILICON—A metallic element which, in its pure state, is used as a semiconductor.

SILICON-CONTROLLED RECTIFIER (SCR)— A semiconductor device that functions as an

electrically controlled switch.

SOLID-STATE DEVICE—An electronic device which operates by the movement of electrons within a

solid piece of semiconductor material.

THERMAL RUNAWAY—A conduction that exists when heat causes more electron-hole pairs to be

generated; which, in turn, causes more heat and may eventually cause diode destruction.

TRANSISTOR—A semiconductor device with three or more elements.

TRIAC—A three-terminal device that is similar to two SCRs back to back with a common gate and

common terminals. Although similar in construction and operation to the SCR, the TRIAC controls

and conducts current flow during both alternations of an ac cycle.

TRIVALENT IMPURITY—Acceptor impurities containing only three valence electrons.

TUNNEL DIODE—A heavily doped semiconductor device that has high gain and fast switching

capabilities.

UNIJUNCTION TRANSISTOR (UJT)— A three-terminal, solid-state device that resembles a transistor

but is stable over a wide range of temperatures and allows a reduction of components when used in

place of a transistor. Used in switching circuits, oscillators, and wave-shaping circuits.

AI-7

VARACTOR—A diode that behaves like a variable capacitor, with the PN junction functioning like the

dielectric and the plates of a common capacitor.

VOLTAGE GAIN—Ratio of voltage across a specified load.

VOLTAGE MULTIPLIERS—Methods of increasing voltages used primarily where low current is

required.

ZENER DIODE—A PN-junction diode designed to operate in the reverse-bias breakdown region.

ZENER EFFECT—A reverse breakdown effect in diodes in which breakdown occurs at reverse

voltages below 5 volts. The presence of a high energy field at the junction of a semiconductor

produces the breakdown.