Multiple non-monotonic quantizer regions for noise shaping

Abstract

A signal processing system having a multiple non-monotonic regions quantization transfer function can improve overall delta sigma modulator performance. The non-monotonic quantization transfer function includes multiple quantization level retrograde changeover thresholds. Thus, the quantizer makes retrograde quantization level decisions for predetermined signal levels in multiple non-monotonic regions, i.e., for the ith non-monotonic quantization region 1≦i≦N, N≧2, and quantizer transfer function Q(s), Q(s1i)≦Q(s2i) for a first set of quantizer input signals |s1i|>|s2i| and Q(s3i)≦Q(s4i), for a second set of quantizer input signals |s3i|>|s4i|. The retrograde quantization level decisions for multiple non-monotonic regions, i.e. Q(s3i)≦Q(s4i), for |s3i|>|s4i|, effectively provide positive feedback to the delta sigma modulator input signal for each of the N non-monotonic regions and result in a more carefully defined gain for the delta sigma modulator.

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