Feedback Dithering for Decorrelating Quantization Noise and Enhancing SNDR

This paper presents a novel feedback dithering scheme. The dithering circuit feeds the quantization noise through a resonator and a comparator to produce a binary signal for use as a dither input to a quantizer. The outstanding feature of the feedback binary dither is its capacity to eliminate in-band quantization noise while effectively randomizing quantization patterns and linearizing a quantizer. The feedback dither exhibits a consistently high decorrelation performance in either an open-loop or a closed-loop system. The dithering scheme is applied to a bandpass sigma-delta modulator and a multilevel class-D power amplifier to confirm its effectiveness. Simulations indicate significantly improved in-band signal-to-distortion-plus-noise ratios over the conventional ditherings.