A Low Noise Analog Frontend with Wide Temperature and Supply Ranges for Capacitive MEMS Microphones

In this paper, a front-end interface for capacitive MEMS microphone has been designed and optimised for all PVT corners, which are 1.6V to 3.6V supply voltages, −40°C to 125°C temperature range and comprehensive process variation. It consists of a source follower as the input buffer and a chopper-stabilized amplifier as a calibration stage. To handle the low-noise and high-dynamic-range requirements at the same time, temperature-dependent current biasing and common-mode splitting techniques have been adopted. Verification has been done via post-layout simulations, and the proposed frontend implemented in $\mathbf{0}.\mathbf{18}-\mu \mathbf{m}$ CMOS process achieves 68.9dB SNR with 94 dBSPL input and 124 dBSPL AOP at worst scenarios with a typical −38dBV/Pa microphone. Besides, the proposed system eliminates the necessity of LDO, which could further lower the power consumption.