Compensation of loop-delay quantizer in continuous-time and hybrid sigma-delta analog-to-digital modulators

摘要

A summing-tracking quantizer additively combines multiple feed-forward outputs of cascaded integrator stages of a sigma-delta analog-to-digital converter with a scaled sampled analog signal, and a delayed scaled analog input signal. The summing tracking quantizer compensates for loop delay within a sigma-delta analog-to-digital converter. A loop delay compensation digital-to-analog converter for a sigma-delta analog-to-digital converter is merged with the voltage reference generator within the summing-tracking quantizer. The summing tracking quantizer selects reference voltages from the voltage reference generator based on a previous digital output code. The summing-tracking quantizer has a matrix switch that receives the previous digital output code and selects the reference voltage for applying to comparators for determining a differential quantization code that is additively combined to the previous digital output code to determine the present digital output code.