A novel highly stable high-resolution oversampled Σ-Δ A/D converter configuration

Abstract

This paper is concerned with the development of a novel highly stable high-resolution oversampled /spl Sigma/-/spl Delta/ A/D converter configuration. The resulting /spl Sigma/-/spl Delta/ A/D converters are based on the realization of magnitude-squared complementary or magnitude complementary signal and noise transfer functions. These A/D converters embody three important practical advantages as compared to the hitherto feedforward and multiple-feedback A/D converters, including (a) their noise transfer function can be obtained without any recourse to numerical optimization (simplifying the design process), (b) their noise transfer function is guaranteed to be bounded below unity, resulting in a highly stable A/D converter operation, and (c) in the signal band, where the magnitude of the signal transfer function is unity, the magnitude of their noise transfer function is automatically zero, resulting in a high SQNR (signal-to-quantization-noise ratio) in an actual (nonlinear) converter operation.