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field-effect transistor
field-effect transistor (FET) A semiconductor device having three terminals: source, gate, and drain. Current flow in a narrow conduction channel between drain and source is controlled by the voltage applied between gate and source, which can deplete the conduction channel of charge carriers. If the source and drain regions are composed of n-type semiconductor the conduction channel is n-type; these devices are known as n-channel devices. Devices with p-type source, drain, and channel are called p-channel devices. In contrast to bipolar transistors, FETs are unipolar devices; the current flow is electrons (in n-channel devices) or holes (in p-channel devices).
In the junction FET the channel is a composite part of the structure. In the MOSFET the gate is insulated from the source and drain regions and the channel forms when the gate voltage is applied. Unlike the bipolar transistor both types of FET require virtually no input current to the gate except a pulse to charge or discharge the gate capacitance. Junction FETs have relatively slow switching speeds compared with MOSFETs and bipolar transistors, and are therefore not used in logic circuits. FETs appear in vast numbers in microprocessor chips and similar devices. |
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Cite this article
JOHN DAINTITH. "field-effect transistor." A Dictionary of Computing. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. JOHN DAINTITH. "field-effect transistor." A Dictionary of Computing. 2004. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O11-fieldeffecttransistor.html JOHN DAINTITH. "field-effect transistor." A Dictionary of Computing. 2004. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O11-fieldeffecttransistor.html |
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field-effect transistor
field-effect transistor see transistor . |
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Cite this article
"field-effect transistor." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "field-effect transistor." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1E1-X-fieldeff.html "field-effect transistor." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-X-fieldeff.html |
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