Question

A band-limited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through________.

• A. RC filter
• B. envelope detector
• C. PLL
• D. Ideal low pass filter with the appropriate band width

Hint:

Perfect reconstruction from Nyquist-rate samples requires an ideal low-pass filter with correct bandwidth.

Answer 1

The Correct Option is D

According to the Nyquist-Shannon sampling theorem:
- A band-limited signal (maximum frequency \( f_{max} \)) can be exactly reconstructed if sampled at \( \geq 2f_{max} \).
- The ideal reconstruction filter is an ideal low pass filter with cutoff frequency \( f_{max} \).
The LPF removes replicas of the spectrum that appear due to sampling, leaving only the baseband component.