Question

Which of the following is untrue about Sigma-Delta ADC?

(a) fs>2fmax

(b) Zero crossing detector consists of a sample and hold circuit

(c) Aperture jitter is minimized due to integration

(d) The integrating filter is preceded by a zero crossing detector

I got this question during an interview.

My question is based upon ADC Tradeoffs topic in section Technology Tradeoffs in Software Defined Radio of Cognitive Radio

Answer 1

The correct answer is (b) Zero crossing detector consists of a sample and hold circuit

The explanation: Sigma-Delta ADC does not require a sample and hold circuit. The zero-crossing detector can be implemented by threshold logic.