A tutorial discussion of the oversampling method for A/D and D/A conversion

Oversampling A/D and D/A conversion is discussed with emphasis on sigma-delta structures. Oversampling A/D converters modulate their analog inputs into short digital words at a very high sampling rate. Decimation filters resample this code at the Nyquist rate of the signal and increase the word length to maintain resolution. At the D/A, interpolating filters increase the word rate of the digital code by more than an order of magnitude. This code is demodulated to analog form at high speed using very few levels