A 132 dBSPL 67.34 dB-A SNR Single-Ended MEMS Microphone Using Self-Adaption Loop With 1.5-V Supply Voltage

This article reports a high acoustic overload point (AOP) single-ended digital MEMS microphone system. For audio applications in high sound pressure environments, a high AOP MEMS microphone is required. The nonlinearity of MEMS microphone is contributed by the MEMS sensor and the signal path of the readout ASIC. For the MEMS sensor with fixed sensitivity, the low analog supply voltage in the readout ASIC is the main limitation to achieve high AOP. To address this challenge, a single-ended digital MEMS microphone system with a self-adaption loop (SAL) is proposed. The SAL automatically adjusts the gain of the analog front end and the digital back end by detecting the input signal, breaking the limitation of the analog supply voltage on the AOP of the system. Besides, the proposed system features an always-on characteristic, and the power consumption is scalable. A prototype is realized in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.153~\mu $ </tex-math></inline-formula>m CMOS process, performing 67.34 dB-A SNR with an AOP of 132 dB SPL, consuming <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$738~\mu $ </tex-math></inline-formula>A at 2.4 MHz sampling rate and 1.5-V supply voltage.