A multi-mode SC audio ΣΔ Modulator for MEMS microphones with reconfigurable power consumption, noise-shaping order, and DR

摘要

This paper presents a reconfigurable SC audio ΣΔ modulator implemented in a 0.18-mm CMOS technology. The 0.4-mm2 ΣΔ modulator, based on a 2-2 MASH architecture, features several different operating modes in which noise-shaping order, number of output bits, sampling rate, and signal bandwidth can be programmed. The power consumption is always minimized for the selected operating mode. The achieved performances range from 99-dB DR with 4th-order noise shaping over a 20-kHz bandwidth, while consuming 0.97 mW to 85-dB DR with 2nd-order noise shaping over a 4-kHz bandwidth, while consuming 100 μW. Thanks to its reconfigurability, the proposed device can be used either to read-out different sources (microphones) or to operate in different modes within the same system (i. e. with the same microphone in different scenarios). Compared to single-mode devices, such a reconfigurable ΣΔ modulator trades off slightly lower performance with higher system-level efficiency when different operating modes are required concurrently.