An ideal OPAMP circuit with a sinusoidal input is shown in the figure. The 3 dB frequency is the frequency at which the magnitude of the voltage gain decreases by 3 dB from the maximum value. Which of the options is/are correct?

Question

Question

This question was previously asked in

GATE EC 2022 Official Paper

Answer 1

F3 Madhuri Engineering 06.04.2022 D25

The given op-amp is inverting type, hence the gain is given as:

$\frac{V_{o}}{V_{i n}} = - \frac{2000}{1000 + \frac{1}{j ω \times 10^{- 6}}}$

$\frac{V_{0}}{V_{i n}} = \frac{- 2}{1 + \frac{1}{\frac{j ω}{1000}}}$

At ω = ∞

$G a i n = \frac{V_{0}}{V_{i n}} = - 2$

At ω = 0

$G a i n = \frac{V_{0}}{V_{i n}} = 0$

Hence the given op-amp is High Pass Filter.

Now, the 3 dB Cut-off frequency is given as:

$ω_{c} = \frac{1}{R_{1} C_{1}} = \frac{1}{10^{3} \times 10^{- 6}}$

ωc = 1000 rad/sec

Hence, option (b) and (c) is correct.