Topic: Analog Circuits
Input voltage applied to a circuit is 1 V rms and the output is 1 mV rms. Net gain of the circuit is
- A. +30 dB
- B. -30 dB
- C. -60 dB
- D. +60 dB
Answer: C. -60 dB
Explanation: Voltage gain in dB is given by $Gain(dB) = 20 \log_{10}\left(\frac{V_{o}}{V_{i}}\right)$.
Here, $V_{i} = 1 \text{ V}$ and $V_{o} = 1 \text{ mV} = 10^{-3} \text{ V}$.
$Gain(dB) = 20 \log_{10}\left(\frac{10^{-3}}{1}\right) = 20 \log_{10}(10^{-3}) = 20 \times (-3) = -60 \text{ dB}$.