Question

In a small signal equivalent model of an FET, What does gm VGS   stand for?

(a) A pure resistor

(b) Voltage controlled current source

(c) Current controlled current source

(d) Voltage controlled voltage source

This question was addressed to me in exam.

This question is from The FET Small-Signal Model topic in division Field-Effect Transistors of Electronic Devices & Circuits

Answer 1

Right answer is (b) Voltage controlled current source

For explanation I would say: For FET, the voltage is applied across the gate and source to control the drain current, hence while writing small signal model of an FET, on the output side gm VGS  represents a current source which can be controlled by the input voltage VGS.