Question

Find the relative change in gain with negative feedback given that return ratio is 24, and feedback factor is 3, when the change in open loop gain is 2.

(a) 1

(b) 1.6

(c) 0.1

(d) 0.01

This question was posed to me during an online interview.

My question is from Effects of Feedback topic in portion General and Feedback Amplifiers of Analog Circuits

Answer 1

Right answer is (d) 0.01

To explain: AF = A/(1+Aβ)

Aβ = 24

A = 8

Relative change in gain = dAF/AF = dA/A(1+Aβ)

dAF/AF = 2/8*25 = 0.01.