Glossary - Discrete Semiconductors

Glossary - Discrete Semiconductors

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

ANALOG AMPLIFIER (LINEAR) - A circuit whose output waveshape is an amplified version of its input waveshape. Also called a LINEAR AMPLIFIER.

ANALOG SWITCH - A digitally controlled switch that provides a conductive path for a linear or analog voltage in its ON state

ANODE - One of the two terminals of a diode (positive type material) or the output terminal (also positive type material) of a silicon controlled rectifier (SCR)

BASE - The input terminal of a bipolar transistor

BETA - The Greek letter that designates the current gain of a bipolar transistor. It is the ratio of the transistor's output current (IC) to its input current (IB).

BIAS VOLTAGE - The DC voltage applied across the terminals of a PN junction , whether the device is a diode, bipolar transistor, or JFET. A PN junction is forward biased when a positive voltage is applied to the P-region with respect to the N-region, and reversed biased when the voltage polarity is reversed.

BIPOLAR TRANSISTOR - A three-terminal semiconductor component with a three-layer structure of alternate negative and positive type materials (NPN or PNP). It provides current gain and voltage amplification in a circuit.

BRIDGE RECTIFIER - Four semiconductor diodes configured as a bridge that acts to change AC to full-wave pulsating DC

CATHODE - One of the two terminals of a diode (negative type material) or the terminal (also negative type material) that is common to both input and output sections of an SCR

CHIPS - Unpackaged diodes, bipolar transistors, SCRs, TRIACs, and field-effect transistors (FETs) - also called DICE.

CMOS (COMPLEMENTARY MOSFET) - A combination of an N-channel and a P-channel MOSFET in a single switching circuit. This circuit features very low power dissipation and the effective elimination of an external load resistor. The device responds to a digital pulse at its input by turning one section of the device ON and the other OFF, causing the turned OFF section to act as its high-resistance load. When the input pulse reverts to zero, the state of the two sections of the device are reversed.

COLLECTOR - The output terminal of a bipolar transistor

COMPLEMENTARY BIPOLAR TRANSISTORS - An arrangement of NPN and PNP bipolar transistors in which the polarity of the supply voltage applied to one device is the reverse of the other. The two transistors normally have identical electrical characteristics and are used as a matched pair.

DIAC - A two-terminal bidirectional semiconductor diode AC switch used for triggering a TRIAC

DIFFUSION - One of a series of steps in the fabrication of a semiconductor. This step introduces a small amount of a chemical element, called impurity or dopant, into the substrate. These steps will produce either N-type or P-type regions to create the function of a desired component on the chip.

DIGITAL SWITCH - A switching circuit that turns ON and OFF in response to a digital or step-function pulse

DIODE - A two-terminal semiconductor device that will allow current to flow through it in only one direction. With the proper voltage polarity across the device, it will act as a conductor. When the voltage polarity is reversed, the device will act as a nonconductor, allowing no current to flow.

DOPANT - See IMPURITY

DRAIN - The output terminal of a JFET or MOSFET

EMITTER - One of the terminals of a bipolar transistor that is generally used as the terminal common to both the input and output sections of the device

EPITAXY - See EPITAXIAL GROWTH.

EPITAXIAL GROWTH (EPI) - An optional step in the semiconductor manufacturing process in which a blank silicon wafer is prepared for fabrication. Silicon is precipitated in gaseous form to grow on the surface of the silicon wafer.

FET (FIELD-EFFECT TRANSISTOR) - either a Junction FET (JFET) or a Metal Oxide Semiconductor FET (MOSFET). It is a three-terminal semiconductor that acts either as an amplifier or digital switch. One of the major characteristics of a FET is that is has an extremely high input resistance and therefore, has no loading on previous circuitry.

FORWARD RECOVERY TIME - The length of time required for a diode in its reverse biased (OFF) state to recover to a stabilized ON state after a digital forward bias voltage is applied. If this time is 50 nanoseconds or less, the diode is applicable for use in computers and/or high-speed logic circuits.

FULL-WAVE RECTIFIER - A configuration of either two or four diodes that acts to change AC to full-wave DC The two-diode configuration is used in conjunction with a center-tapped secondary of a transformer. The four diode configuration is used when no center-tap exists at the transformer secondary and is called a BRIDGE RECTIFIER.

GATE - The input or control terminal of an SCR, TRIAC, or FET

HALF-WAVE RECTIFIER - A single diode that acts to change AC to half-wave pulsating DC

IMPURITY - An element added to the semiconductor substrate material (either germanium, silicon, or gallium arsenide) in the fabrication process to create a P-type or N-type region. For germanium, the impurities are arsenic and bismuth. For silicon, the impurities are boron, phosphorus, and aluminum. and for gallium, arsenic and phosphorus.

ISOWATT PACKAGE - An electrically isolated-case version of the TO-18 package.

JFET (JUNCTION FIELD-EFFECT TRANSISTOR) - A three-terminal semiconductor device constructed with a PN junction at its input and a conducting channel as the output section. The PN junction of the input section is reverse biased to provide an extremely high input resistance. It is generally utilized in a high-input resistance, linear amplifier circuit.

LINEAR AMPLIFIER - See ANALOG AMPLIFIER (LINEAR).

MAIN TERMINAL 1 AND MAIN TERMINAL 2 - The output terminals of a TRIAC, alternately acting as an anode or a cathode as its AC supply voltage varies from positive to negative.

MOSFET (METAL-OXIDE SEMICONDUCTOR FIELD-EFFECT TRANSISTOR) - A three-terminal semiconductor component with a built-in capacitor at its input and a conducting channel in its output structure. It has an extremely high input resistance and is either an enhancement type or enhancement/depletion type. The enhancement type MOSFET operates as a normally-off digital switch or as an analog switch. The enhancement/depletion type operates as an extremely high-input resistance linear amplifier.

PINCH-OFF VOLTAGE - That value of reverse bias voltage applied to the input of a J-FET linear amplifier to cut off its channel and reduce its output current to zero

PN JUNCTION - The simplest semiconductor structure. As a discrete device, it is called a diode. It consists of a positive or P-region (containing positive ions) in junction with a negative or N-region (containing negative electrons).

RECTIFIER - A semiconductor diode, or group of diodes, that acts to change AC to pulsating DC

SCR (SILICON CONTROLLED RECTIFIER) - A silicon device with four layers (PNPN) having an input control terminal (gate), an output terminal (anode) and a terminal common to both input and output (cathode). It generally operates as an AC switch for lighting and heating control.

TRIAC (TRIODE AC SWITCH) - A three-terminal silicon device that functions as two SCRs configured in an inverse, parallel arrangement, providing a means of providing load current during both halves of the AC supply voltage. A TRIAC is generally used for motor speed control. Since load current (armature current) flows during both halves of the applied AC voltage, the motor rotates smoothly at all rotational speeds.

VARACTOR - A semiconductor diode that acts as a variable capacitor whose value changes inversely to reverse bias voltage.

ZENER - A semiconductor diode with the unique characteristic of providing a predictable value of voltage breakdown (called zener voltage) when in its reverse biased mode. At the breakdown mode, it exhibits a very sharp break from its nonconducting state into its breakdown state, maintaining a constant value of reverse voltage across it. The zener diode operates as a voltage regulator, voltage reference, and excess voltage circuit protection device.