Reduced area digital sigma-delta modulator

Abstract

A digital sigma-delta modulator requiring minimal die area and dissipating minimal power is formed with a plurality of integration stages coupled in tandem between an input node and an output node. The bit width of signals in the integration stages is progressively reduced from the first to the last integration stage without compromising modulator accuracy. A quantizer between the last integration stage and the output node provides the final reduction of signal bit width. The gain of the modulator feedforward and feedback paths are integer powers of two to further simplify the digital computation. In an exemplary implementation, three integration stages to form a third-order modulator are coupled in tandem between the input node and the output node. The gains of feedback and feedforward paths in one preferred embodiment are unity, and in some embodiments, one feedforward path has gain of 0.5.