This brief presents a programmable-gain analog readout circuit with a noise-reduction input buffer for single-ended micro-electro-mechanical-system (MEMS) microphone sensors, aiming at applications requiring low cost and high SNR. An internal feedback path is adopted in the source-follower-based input buffer to suppress the noise contribution from its bias circuit, while improve the linearity and power supply rejection ratio (PSRR). In addition, another feedback path taking advantage of the readout circuit’s high-voltage bias output for the MEMS sensor is employed to realize an effective gain of larger than unity for the input buffer, which can suppress the noise contribution of the programmable capacitive-feedback preamplifier. Fabricated in a 0.18- $\mu \text{m}$ CMOS technology, the proposed readout circuit achieves a 3.7- $\mu $ Vrms (A-weighted) input-referred noise. After packaged with a commercial MEMS microphone sensor, the overall system achieves an A-weighted SNR of 66 dBA, an acoustic overload point (AOP) of 119.5 dB sound pressure level (SPL) and a PSRR of 68 dB@1kHz. The readout chip consumes 115 $\mu \text{A}$ under a 2-V power supply and occupies an active area of 0.25mm2.

中文翻译：

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用于 MEMS 麦克风的具有降噪输入缓冲器的模拟读出电路

本简介介绍了一种用于单端微机电系统 (MEMS) 麦克风传感器的具有降噪输入缓冲器的可编程增益模拟读出电路，旨在满足需要低成本和高 SNR 的应用。基于源极跟随器的输入缓冲器采用内部反馈路径，以抑制其偏置电路的噪声贡献，同时提高线性度和电源抑制比 (PSRR)。此外，利用读出电路对MEMS传感器的高压偏置输出的另一条反馈路径被用来实现输入缓冲器的大于1的有效增益，这可以抑制可编程电容反馈前置放大器的噪声贡献. 制造在 0.18- $\mu \text{m}$CMOS技术，所提出的读出电路实现了3.7- $\亩$ Vrms（A 加权）输入参考噪声。与商用 MEMS 麦克风传感器封装后，整个系统实现了 66 dBA 的 A 加权 SNR、119.5 dB 声压级 (SPL) 的声学过载点 (AOP) 和 68 dB@1kHz 的 PSRR。读出芯片消耗115 $\mu \text{A}$在 2V 电源下，占用 0.25mm2 的有效面积。