What is the technique of deliberately sampling a signal centered at 70 MHz with a 10 MHz bandwidth at a lower sampling frequency, which also performs frequency conversion?

Answer: C. Undersampling (bandpass sampling)

A band-limited signal can be captured with a sampling frequency of at least twice its bandwidth by using aliasing to fold it down to a lower frequency. This is called undersampling (bandpass sampling) and is used in radio receivers, for example to eliminate a mixer. It requires the ADC's input bandwidth to extend to the signal frequency and low clock jitter.

• A. Noise shaping pushes quantization noise toward higher frequencies.
• B. Oversampling means sampling at a higher rate than necessary.
• C. Correct. It deliberately uses aliasing to capture a bandpass signal.