Equivalent open-loop system for a general class of sigma-delta modulator configurations

Abstract

This paper presents an equivalent open-loop system for the exact analysis and characterization of a general class of sigma-delta (/spl Sigma/-/spl Delta/) modulator configurations. This open-loop system is based on the exploitation of the closed-form solution of the granular error (i.e. the error under no-overload operation) associated with the constituent coarse quantizer. The proposed open-loop system is subsequently applied to the determination of the signal-to-quantization noise ratio for the class of /spl Sigma/-/spl Delta/ modulator configurations under consideration. The results are illustrated through their application to a triple-loop /spl Sigma/-/spl Delta/ modulator for DC as well as AC input signals.