9.5 A 1.8V true-differential 140dB SPL full-scale standard CMOS MEMS digital microphone exhibiting 67dB SNR

Abstract

Over the last few years, robust MEMS microphones have gained significant market share in consumer applications such as mobile phones and hearing aids. The consumer market is demanding improved quality for audio recording, while also being capable of suppressing high-energy disturbers, e.g., wind noise. The challenge is to achieve both high DR and SNR at low supply voltages that limit signal swing. Signal levels are expressed in dB Sound-Pressure-Level (dB SPL) with respect to the human hearing threshold at a sound pressure of 20μPa corresponding to 0dB SPL. Today's mass-market MEMS digital microphone solutions typically process sound up to 120dB SPL.