An analysis of nonlinear behavior in deltasigma modulators
Abstract
The paper introduces a new method of analysis for deltasigma modulators based on modeling the nonlinear quantizer with a linearized gain, obtained by minimizing a meansquareerror criterion, followed by an additive noise source representing distortion components. In the paper, input signal amplitude dependencies of deltasigma modulator stability and signaltonoise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signaltonoise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable thirdorder deltasigma modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomena are explained by the nonlinear analysis of this paper. The analysis is carried out for both dc and sinusoidal excitations.
 Publication:

IEEE Transactions on Circuits Systems
 Pub Date:
 June 1987
 Bibcode:
 1987ITCS...34..593A
 Keywords:

 Amplification;
 Analog To Digital Converters;
 Delta Modulation;
 Nonlinear Systems;
 Counters;
 High Resolution;
 RootMeanSquare Errors;
 Signal To Noise Ratios;
 Communications and Radar