Third-order Sigma Delta modulator feedback coefficients for maximum dynamic range

A new analysis of the third-order Ca modulator is based on parameterization of the comparator gain and the fact that the one-bit quantizer delivers co nstant output power. It is shown that a wrong choice of feedback coefficien ts reduces the dynamic range considerably. The new analysis derives a set o f feedback coefficients to give the best large input signal handling capabi lities. The quantization noise and its spectrum are evaluated in order to f ind the signal-to-noise dynamic range for each case. Optimum feedback coeff icients are then chosen to give maximum signal-to-quantization noise ratio. A comparison with non-ideal coefficients is also shown. The choice of non- ideal coefficients may reduce the circuit complexity.