MASH sigma-delta modulators with reduced sensitivity to the circuit non-idealities

In this paper several techniques are presented to significantly relax the analog circuit requirements such as the amplifiers dc gain and capacitors matching of multi-stage noise-shaping (MASH) sigma-delta modulators. In the first technique, one order redundant noise shaping is employed in the early stages and the first order shaped quantization error of the early stages is used as the input of the succeeding stages. In the second technique, a high order SigmaDelta modulator is used in the first stage and the overall noise shaping is only performed by the analog filtering. Simulation results and mathematical analysis are provided to demonstrate the usefulness of the proposed structures.