Question

If an electronic system produces a 48mV output voltage when a 12mV signal is applied, calculate the decibel value of the systems output voltage gain.

(a) 12dB

(b) 6dB

(c) 20dB

(d) 4dB

I had been asked this question during an interview.

My question comes from General Frequency Consideration topic in chapter Transistor Biasing and Low Frequencies of Analog Circuits

Answer 1

Correct choice is (a) 12dB

Easy explanation: Gain of the system is = output voltage/input voltage

= 48/12 = 4

Gain in dB = 20 log(voltage gain)

= 20 log(4) = 12.04 dB.