Trans conductance of MOSFET in linear region can be approximated by ______

Question

Question

This question was previously asked in

DFCCIL Executive S&T 2018 Official Paper

Answer 1

Explanation:

For a MOSFET operating in the linear region, the current is given by:

---(1)

W = Width of the Gate

Cox = Oxide Capacitance

μ = Mobility of the carrier

L = Channel Length

Vth = Threshold voltage

The transconductance is defined as the change in drain current for a given change in Gate-to-source voltage, i.e.

Differentiation equation (1) with V_GS we get:

as g_m ∝ V_DS

g_m ≈ KV_DS

Hence option (2) is the correct answer.

Important Points

For a MOSFET in saturation, the current is given by:

The transconductance of a MOSFET is defined as the change in drain current(ID) with respect to the corresponding change in gate voltage (VGS), i.e.

Hence in saturation mode, transconductance does not depend on V_DS