A volterra series-enhanced model to predict the non-linear sampling distortion in flash A/D converters due to substrate noise

This paper proposes a Volterra-enhanced model to evaluate the impact of substrate noise on CMOS regenerative comparators and on flash A/D converters. The presented approach initially extends the linear model of the non-uniform sampling (NUS) distortion of the comparator due to substrate noise, to include 2^nd and 3^rd order non-linearities. The effectiveness of the enhanced model is then evaluated by studying the HD₂ and HD₃ distortion. Subsequently, the obtained expression for the timing uncertainty is used to derive a generalized expression for the SNDR reduction in flash A/D converters that incorporate the analyzed comparators. The developed approach is validated on a 10-bit flash A/D by comparing the prediction of the linear and the Volterra-enhanced model.