Systematic design of double-sampling ΣΔ ADC´s with modified NTF

A disadvantage of double-sampling ΣΔ ADC´s is their sensitivity to path mismatch. Recently, an approach to solve this problem was presented. It consists of modifying the noise transfer function (NTF) of the modulator such that it has a zero at the Nyquist frequency, next to those in the baseband. Unfortunately, no systematic design strategy for such ADC´s is available. In this work, we present such a strategy. It consists of finding optimal pole positions for the modified NTF. This can be combined with optimizing the zeros of the NTF. Next, we introduce an efficient structure that has enough flexibility to realize the optimized pole positions.