Question

What is the total voltage gain of a difference amplifier if input of first stage is 50V and the output of the second stage is 100V?

(a) 20

(b) 0.2

(c) 2.5

(d) 2

The question was posed to me in unit test.

This intriguing question originated from Transistor Difference Amplifiers topic in chapter Low Frequency Transistor Amplifier Circuit of Electronic Devices & Circuits

Answer 1

Right choice is (d) 2

The explanation is: The total gain of a difference amplifier is the ratio of the output of second stage amplifier to the input of first stage amplifier. Where, Voutput = 100V and Vinput = 50V.

AV = Voutput / Vinput = 100V / 50V = 2