Why BJT is known as current controlled device and FET is known as voltage controlled device?

swathi

• Apr 9th, 2015

In BJT we give input as a current to the base so it operates taking small input current signal and gives large output current signal so it is called current controlled.
in FET we give input voltage signal to the gate so the output will be of current signal so it is called voltage controlled device.

uzipereg

 Profile Answers by uzipereg Questions by uzipereg

• Jul 30th, 2011

For Active BJT: Ic = BETHA * Ib
(the collector/output current is controlled by the base/input current)

Saturated MOSFET: Id= 0.5*u*Cox*(W/L)*Vod, where Vod is the overdrive voltage: Vod= Vgs - Vt
(the drain/output current is controlled by the overdrive voltage)

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