Two-stage decimation filter design technique for oversampling Δ-Σ A/D converters

Practical considerations restrict the usefulness of all but the simplest comb filters as the first-stage decimators in oversampling delta-sigma A/D converters due to the large oversampling ratios. A design technique is thereupon presented for two-stage decimators in oversampling delta-sigma A/D converters. This design technique takes into account the noise shaping in the delta-sigma modulator and the requirements of the whole A/D converter in order to optimize the decimator. The optimum decimators are also derived in order to achieve the maximum resolution performance