Prediction of non-uniform sampling distortion due to substrate noise coupling in regenerative comparators

Abstract

This paper analyses the sampling uncertainty in regenerative comparators due to substrate noise coupling and provides a model for the resulting sampling distortion power. The analysis identifies two contributors of the total sampling uncertainty: the input signal-dependent one and the substrate noise-related one. The two disturbances of the ideal operation of the sampling transistors cause a non-uniform sampling operation, whose properties depend on the frequencies of the disturbing signals. The non-uniform sampling introduces distortion components mainly at the harmonics of each interference signal, and other components located at frequencies related to the spectral content of the interference signals and the sampling frequency. The experimental results indicate that the developed model manages to capture accurately all the aforementioned distortion components in the presence of any input and any substrate noise signal, and therefore to predict the overall sampling distortion power.