Dither and Noise Modulation in Sigma Delta Modulators
In recent years there has been considerable debate over the suitability of 1-bit Sigma-Delta modulation (SDM) for high-quality applications. Much of the debate has centered on whether it is possible to properly dither such a system. It has been shown that dither with a triangular probability distribution should be applied to the quantizer input in a pulse code modulation system. This is not the case for all A/D converters. We show that the dependence of error moments on input is inherently different in sigma delta modulators, and that the effect of dither depends on whether the quantiser is one bit or multibit. These statements are proven for simple SDMs and verified by simulation.
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