The high Signal-to-Noise ratio that can be achieved by high-order one-bit sigma delta modulators has led to the wide spread application of these modulators as oversampled A/D converters. However, the stability of the nonlinear feedback loop of the modulators has yet to be proven. Caused by the nonlinearity of the quantizer, stability methods for linear systems such as the Routh-Hurwitz test are not applicable. The nature of the instabilities also requires a refinement of the definition of stability within the context of SDMs.
KeywordsInput Signal Unit Circle Loop Filter Root Locus Sigma Delta Modulator
Unable to display preview. Download preview PDF.