Question

What is the value of voltage gain in decibels if Voutput = 20V and Vinput = 15V?

(a) 1.75dB

(b) 2.28dB

(c) 1.37dB

(d) 2.48dB

I have been asked this question during an interview.

My enquiry is from The Decibel topic in division Low Frequency Transistor Amplifier Circuit of Electronic Devices & Circuits

Answer 1

The correct answer is (d) 2.48dB

For explanation: The voltage gain in terms of decibels is expressed as 20 × log (Voutput / Vinput) . Given, Voutput = 20V and Vinput = 15V.

Voltage gain = 20 × log (Voutput / Vinput) = 20 × log (1.33) = 20 × 0.1239 = 2.48dB.