Question

For a self bias amplifier, RS=RD, the output will be_________________

(a) Same as Input

(b) Same as input but phase reversed

(c) 0

(d) Infinite

I had been asked this question by my college director while I was bunking the class.

My doubt stems from The Common Source Amplifier topic in division Field-Effect Transistors of Electronic Devices & Circuits

Answer 1

Correct choice is (b) Same as input but phase reversed

The best I can explain: Av=-gm RD/ (1+gm RS),

If RS=RD, Av=-gm RD/ (1+gm RD) => Av  is nearly equal to -1                                                                            Av=Vo/Vi=> Vo=-Vi.