Robust Continuous-Time MASH Delta Sigma Modulator

Abstract

A continuous time (CT) multi-stage noise- shaping (MASH) delta sigma modulator (DSM) with reduced quantization noise leakage is proposed. In this structure, the shaped quantization noise is extracted at an integrator output, and analog noise transfer function (NTF) variations can be cancelled at the MASH output. Therefore, the circuit is insensitive to NTF variations, and no complex digital calibration is needed. The residual quantization noise leakage caused by integrator non-idealities is shaped, and can easily be calibrated to relax the requirements of the integrators. The proposed MASH can use more aggressive NTF than a traditional one, and uses a simpler noise cancellation filter. Simulation results and theoretical analysis verify the effectiveness of this structure.