Multibit Sturdy MASH ΔΣ Modulator with Error-shaped Segmented DACs for Wideband Low-power Applications

Abstract

This paper presents several techniques to enhance the resolution of sturdy multi-stage noise shaping (MASH) ΔΣ modulator (DSM). The proposed structure significantly suppresses the quantization noise (QN) by employing a high-resolution quantizer with a segmented MSB/LSB DAC feedback in the first loop as well as noise coupling techniques in both loops. Reducing QN of the first loop significantly decreases the output swings of the integrators, thus improving the stability of the first loop. Besides, the construction of one extra order shaping function mitigates the leakage of coarse QN introduced by a gain mismatch between MSB and LSB DACs of the high-resolution quantizer. Simulation results demonstrate the effectiveness of the proposed architecture to achieve high resolution while employing low-gain op-amps for all integrators.