Question

A voltage amplifier has a voltage gain of 100. What will be gain at 3dB cut-off frequencies?

(a) 70.7

(b) 80.7

(c) 45.7

(d) 50

I had been asked this question by my school teacher while I was bunking the class.

Question is taken from General Frequency Consideration in division Transistor Biasing and Low Frequencies of Analog Circuits

Answer 1

Right answer is (a) 70.7

Best explanation: 3dB cut-off frequency is the frequency at which the power becomes half of its maximum value. That is the voltage gain becomes 0.707 times maximum voltage gain. Therefore if voltage gain is 100 then gain at 3dB frequencies will be

100 x 0.707 = 70.7.