A 106.7-dB DR, 390-μW CT 3rd-order ΣΔ modulator for MEMS microphones

Abstract

A 3^rd-order continuous-time ΣΔ modulator for MEMS microphones in 0.16-μm CMOS technology achieves 106.7-dB DR and 93.2-dB peak SNDR, consuming 390 μW from a 1.6-V power supply and occupying an area of 0.21 mm². The ΣΔ modulator, based on a feedforward architecture, uses only two operational amplifiers for achieving the 3^rd-order loop-filter transfer function, a 15-level quantizer, and a feedback DAC with three-level current-steering elements, which minimizes the noise contribution at small input signal, in order to achieve a DR > 100 dB with the largest reported Schreier FoM (184 dB).