Towards a Better Understanding of 1-Bit Sigma-Delta Modulators
Although 1-bit Sigma-Delta modulators cannot be adequately dithered to make their performance perfect, the application of substantial noise shaping gives them modest performance while maintaining reasonable stability. Partial dithering has been shown to improve these devices, but spuriae remain. By simulation we study: (a) the nature of the idle tone, (b) the effect of the order of the shaping filter, (c) the influence of shaper stability, and (d) coherence and incoherence of the shaper's output. Calculation of these features demands high numerical precision and is greatly aided by coherent averaging.
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