MASH ΣΔ Modulator With Filter Mismatch Shaping Technique

Abstract

This brief proposes an improved architecture for multi-stage noise-shaping (MASH) $\Sigma \Delta $ modulators ( $\Sigma \Delta $ Ms), which can reduce quantization noise leakage and eliminate the requirement of high-gain opamps. Based on the proposed filter mismatch shaping (FMS) technique, filter mismatch between analog and digital domains in the MASH $\Sigma \Delta $ M can be mitigated, reducing inband quantization noise leakage and obtaining less sensitivity to opamps gain. Hence, the DC gain of opamps can be minimized, and simpler opamps with fewer stacked transistors would be allowed, facilitating low-voltage and energy-efficient operation. Fabricated in 55-nm CMOS and sampled at 3.2 MHz, the prototype modulator achieves a peak SNDR of 77.4 dB in a 110.3-kHz bandwidth (BW) while dissipating $116.5~\mu $ W from a 1.2-V supply.