Question

A certain common-source JFET has a voltage gain of 10. If the source bypass capacitor is removed, _____________

(a) the voltage gain will increase

(b) transconductance will increase

(c) voltage gain will decrease

(d) the Q-point will shift

I got this question in a job interview.

My enquiry is from Transconductance Amplifiers in portion Differential and Multistage Amplifiers of Electronic Devices & Circuits

Answer 1

Correct option is (c) voltage gain will decrease

Easiest explanation: In common source JFET, The main purpose of a source bypass capacitor is to provide additional gain at AC. Here, the common-source JFET has a voltage gain of 10; which includes the additional  AC gain provided. If the source bypass capacitor is removed, then the voltage gain will eventually decrease.