A new technique for compensating the influence of the feedback DAC delay in continuous-time bandpass delta-sigma converters

Abstract

A new technique for the synthesis of continuous time bandpass delta-sigma modulators with maximum gain margin and higher loop delay is presented. This method is based on the pulse shaping of the DAC output signal taking into account the loop delay and rise time. It is only based on discrete time analysis. It will be shown that high values of the loop delay together with high filter gain margin can be reached. The gain margin sensitivity to the real loop delay variation can also be improved if a return-to-zero DAC (RZDAC) is used.