field effect transistor

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Related to field effect transistor: Junction Field Effect Transistor

field effect transistor

(FET) A transistor with a region of donor material with two terminals called the "source" and the "drain", and an adjoining region of acceptor material between, called the "gate". The voltage between the gate and the substrate controls the current flow between source and drain by depleting the donor region of its charge carriers to greater or lesser extent.

There are two kinds of FET's, Junction FETs and MOSFETs.

Because no current (except a minute leakage current) flows through the gate, FETs can be used to make circuits with very low power consumption.

Contrast bipolar transistor.
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(Field Effect Transistor) One of two major categories of transistor; the other is bipolar. FETs use a gate element that, when charged, creates an electromagnetic field that changes the conductivity of a silicon channel and turns the transistor on or off. FETs are fabricated as individually packaged discrete components as well as by the hundreds of millions on a single chip.

FETs vs. Bipolar
FET-based silcon chips are easier to construct than their bipolar counterparts. FETs switch a little slower than bipolar transistors, but use less power. Once the gate terminal on an FET has been charged, no more current is needed to keep that transistor on (closed) for the duration of time required. By comparison, a bipolar transistor requires a small amount of current flowing to keep the transistor on. While the current for one transistor may be negligible, it adds up when millions are switching simultaneously. The heat dissipated on bipolar limits the total number of transistors that can be built on the chip, which is why CMOS logic (based on FETs) is used to build chips with millions of transistors.

The most widely used and widely known FETs are MOSFETs (metal oxide semiconductor FETs), which come in NMOS (n-channel) and PMOS (p-channel) varieties. On a chip, NMOS and PMOS transistors are wired together in a complementary fashion to create CMOS logic, which is the most predominant and used in almost every electronic device today. See MOSFET and n-type silicon.

There Are Many Kinds of FETs
Similar to MOSFETs are JFETs (junction FETs), which use a PN junction gate rather than a poly-crystalline gate. Used for microwave communications, MESFETs (metal semiconductor FETs) are similar to JFETs, but use a Schottky metal gate and are made from gallium arsenide or indium phosphide, not silicon. Evolving from MESFETs for higher-frequency applications are HEMTs and PHEMTs (high electron mobility transistors and pseudomorphic high electron mobility transistors). HEMTs are also called MODFETs, TEGFETs and SDHTs (modulation doped FETs, two-dimensional electron gas FETs and selectively doped heterojunction transistors).

Another high-frequency FET is the gallium arsenide-based CHFET (complementary heterostructure FET), which uses a complementary architecture similar to CMOS.

FETs vs. Bipolar
After the gate is charged in an FET, no more current flows, but the transistor remains closed (turned on) during the required time period. Bipolar transistors (BJTs) require current the entire time the transistor must be closed.
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References in periodicals archive ?
The voltage-controlled amplifiers VCAI and VCAII use similar topology, but instead of potentiometers, field effect transistors T1 and T2 are utilized to control the gain.
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Gaggero-Sager, "Transport properties of delta-doped field effect transistor," Progress In Electromagnetics Research Letters, Vol.
Benedetto, "Ferroelectric field effect transistor based on epitaxial perovskite heterostructures," Science, vol.
Mulato, "Extended gate field effect transistor using [V.sub.2][O.sub.5] xerogel sensing membrane by solgel method," Solid State Sciences, vol.
A group of researchers at ST Microelectronics in France, for instance, has fabricated what is claimed to be the smallest manufactured metal oxide semiconductor field effect transistor with n-type channel (NMOSFET) operating at room temperature.
His topics include analog electronics applications and design, the small-signal analysis of an amplifier under different models, field effect transistor biasing, feedback in amplifiers, and the computer-aided simulation of practical assignment.
After a review of carbon-based materials concepts and basic physics, some areas explored include carbon nanotube field effect transistor models, graphene nanoribbon field effect transistors, bilayer and trilayer graphene nanoribbon transport modeling, and silicon nanowire field effect transistor modeling.
Ismail, "Ballistic quantum transport in a nanoscale metal-oxide-semiconductor field effect transistor," Applied Physics Letters, vol.
HVVi Semiconductors introduced its High Frequency, High Voltage Vertical Field Effect Transistor (HVVFET) architecture.
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