Question

What is the reason for connecting a capacitor in parallel with Rs?

(a) It blocks the noise

(b) For ac signal it acts a short circuit resulting in grounding source terminal

(c) It blocks the noise & for ac signal it acts a short circuit resulting in grounding source terminal

(d) To increase impedance

I had been asked this question in quiz.

This question is from The Common Source Amplifier topic in section Field-Effect Transistors of Electronic Devices & Circuits

Answer 1

Right answer is (c) It blocks the noise & for ac signal it acts a short circuit resulting in grounding source terminal

To explain: The capacitor connected across  Source blocks all the DC noise signals, when AC input is applied, at high frequency the capacitive reactance will be almost zero resulting in short circuit making the source to be directly connected to ground.