Question

The value of the voltage gain (Av) for the common source with source resistance (represented by A1) and common gate configuration (represented by A2) are related to each other by

(a) A1 > A2

(b) |A1| > |A2|

(c) A1 < A2

(d) A1 > A2 and |A1| > |A2|

This question was posed to me by my college professor while I was bunking the class.

My enquiry is from Basic MOSFET Amplifier Configurations topic in portion MOS Field Effect Transistors (MOSFETs) of Electronic Devices & Circuits

Answer 1

Correct option is (c) A1 < A2

Explanation: A1 = – gm(RL||RD)/ 1 + gmRS and

A2 = gm(RL||RD)

Reference figure for common source with source resistance configuration

Reference figure for common gate configuration