An optimum cascade structure for the sigma delta modulator
We derive the MSE performance of the single Imp BA modulator for decoders based on average filtering. In doing so, we modify the basic Structnre of the modulator in order to improve its MSE chxacteristics. The modified structure cax either utilize a switch and a single loop modulator or a number of single loop XA modulators cascaded with each other. The hasic idea behind the modified structure is to requantize the residue assciated with each quantization Step in order to reduce the overdl quantization noise. Wc derive the optimum number of stages in the cascade structure for a fixed number of samples, and show the MSE performance of the cascade modulator to be considerably better than that of a single loop modulator.