Transistor

Term derived from "transfer resistor." Semiconductor device that can be used as an amplifier or as an electronic switch.

  • More than 100 million 22nm tri-gate transistors could fit on the head of a pin - Intel

Base

The region that lies betwen the emitter and collector of a bipolar junction transistor (BJT).

Base Biasing

A method of biasing a Bipolar Junction Transistor in which the bias voltage is supplied to the base by means of a resistor.

Base Terminal

That electrode of a transistor which compares generally to the grid of a vacuum tube.

Beta

The current gain in a grounded-emitter transistor amplifier. The symbol for current gain is the Greek letter, b.

Bias

The potential applied between the grid and cathode of a tube or between transistor elements to provide an operating point at zero signal input.

Bias Current

Current that flows through the base-emitter junction of a transistor and is adjusted to set the operating point of the transistor.

Bipolar Junction Transistor

A three terminal device in which emitter to collector current is controlled by base current.

Bottoming

A transistor in the fully conducting state.

Collector

One terminal of a transistor. The semiconductor region in a bipolar junction transistor through which a flow of charge carriers leaves the base region.

Collector Injection Modulator

The transistor equivalent of a plate modulator. Modulating voltage is applied to a collector circuit.

Common Base Connection

Same as ground base connection. A mode of operation in which the base is common to both the imput and output circuits and is usually earthed. The emitter is used as the input terminal and the collector as the output terminal. (Grounded= grounded to AC signals).

Common Collector Connection

Grounded collector connection. Also called the emitter-follower. A mode of operation in which the collector is common to both the imput and the output circuits and is usually connected to one of the power rails.

Common Emitter Connection

Same as ground emitter connection. A mode of operation for a transistor in which the emitter is common to the imput and output circuits. The base is the imput terminal and the collector is the output terminal.

Complementary transistor

A PNP and NPN pair, having near identical characteristics. Used in a push-pull circuit. N-channel and P-channel FETs can also be complementary.

Cutoff

A transistor operating mode where very little current flows between the collector and emitter.

Darlington Pair

Two directly coupled transistors in which the emitter of the first drives the base of the second. Circuit has an extremely high current gain and input impedance.

Depletion-Mode MOSFET

A MOSFET designed to operate in either depletion mode or enhancement mode.

Emitter

One terminal of a transistor. Compares generally to the cathode of a tube. The semiconductor region from which charge carriers are injected into the base of a bipolar junction transistor.

Emitter Coupled Logic

Where transistors are held in the turned-on state to increase the speed of the gate.

Emitter Feedback

Coupling from the emitter output to the base input of a bipolar junction transistor.

Enhancement-Mode MOSFET

A field effect transistor in which there are no charge carriers in the channel when the gate source voltage is zero.

Field Effect Transistor (FET)

A three-terminal transistor device where the output current flowing between the source and drain terminals is controlled by a variable electric field applied to the gate terminal. The gate design determines the type of FET: either JFET (junction FET) or MOSFET (metal-oxide semiconductor FET). Each type has two polarities: positive, or p-channel devices, and negative, or n-channel devices. In a JFET device the gate forms a true semiconductor junction with the channel, while in a MOSFET device the gate is insulated from the channel by a very thin (typically less than the wavelength of light) layer of glass (silicon dioxide) and the gate is either metal or doped silicon (polysilicon), hence the acronym metal-oxide semiconductor.

Forward Bias

The bias applied between the base and emitter of a transistor to coincide with the P and N zone polarities.

Gate

One of the terminals of a Field Effect Transistor (FET).

Grounded Base

A transistor amplifier circuit comparable to the grounded-grid (signal ground) tube circuit.

Grounded Collector

A transistor circuit comparable to the cathode-follower tube circuit. (Also called emitter follower.)

Grounded Emitter

A transistor circuit comparable to the conventional grounded cathode tube amplifier.

H-Parameters (hybrid parameters)

Transistor specifications that describe the component operating linits under specific circumstances.

Insulated gate field effect transistor (IGFET)

Another name for a MOSFET.

Intrinsic Stand-Off Ratio

A unijunction transistor rating used to determine the firing potential of the device.

Junction Field Effect Transistor (JFET)

In a JFET device the gate forms a true semiconductor junction with the channel.

Linear Region

A transistor operating mode where the collector current is proportional to the base current.

Majority Carriers

The term used in transistor design to indicate the primary current-movement process. For a PNP transistor, the holes constitute the chief current carriers.

MOSFET Metal-Oxide-Silicon-Field-Effect-Transistor

the gate is insulated from the channel by a very thin (typically less than the wavelength of light) layer of glass (silicon dioxide) and the gate is either metal or doped silicon (polysilicon), hence the acronym metal-oxide semiconductor.

NPN

Type of bipolar transistor using n-type p-type n-type material in its manufacture.

Operating point

That point in the characteristics of a tube or transistor around which the signal voltages vary.

Phototransistor

A transistor with a window on the top face to allow light to fall on the active surface. Also available as a Darlington photo-transistor to produce a very sensitve light detecting device.

PNP

Type of bipolar transistor using p-type, n-type, n-type semiconductor material.

Potential Barrier

The internal resistance of a transistor related to the internal potential existing between NP junctions.

Programmable UJT

Unijunction transistor with a variable intrinsic stand-off ratio.

Saturation

Condition in which a further increase in one variable produces no further increase in the resultant effect. In a bipolar junction transistor, the condition when the emitter to collector voltage is less than the emitter to base voltage. This condition puts forward bias on the base to collector junction.

Self Biasing

Gate bias for a field effect transistor in which source current through a resistor produces the voltage for gate to source bias.

Silicon Transistor

A bipolar junction transistor using silicon as the semiconducting material.

Switching Transistor

Transistor designed to change rapidly between saturation and cut-off.

Unijunction Transistor

Three terminal device that acts as a diode with its own internal voltage divider biasing circuit.


Historical Notes

  1. 1948 First transistor produced by John Bardeen, Walter Brattain and William Shockley.

See also: Darlington Pair, Field Effect Transistor, Grown Junction, Hole Flow, Insulated Gate Bipolar Transistor, Junction Transistor, NPN Transistor, PNP Transistor, Semiconductor, Silicon Controlled Rectifier, Tetrode, Thyristor, Transistor-Transistor Logic (TTL).

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Subjects: Electronics Semiconductors


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