An Analog Readout Circuit With a Noise-Reduction Input Buffer for MEMS Microphone
An Analog Readout Circuit With a Noise-Reduction Input Buffer for MEMS Microphone
复制标题
一种用于MEMS麦克风的带降噪输入缓冲的模拟读出电路
DOI：
10.1109/tcsii.2022.3186205
复制
发表时间：
2022-10-01
影响因子：
4.4
通讯作者：
Zhang, Hong
中科院分区：
文献类型：
--
作者：
Li, Zhiming;Dong, Lei;Zhang, Hong
针对低成本、高信噪比的应用需求，提出了一种用于单端微机电系统（MEMS）麦克风传感器的带降噪输入缓冲器的可编程增益模拟读出电路。在基于源极跟随器的输入缓冲器中，采用了一种内部反馈路径，以抑制其偏置电路的噪声贡献，同时提高了线性度和电源抑制比（PSRR）。此外，利用读出电路的高电压偏置输出的MEMS传感器的另一个反馈路径被用来实现大于单位的输入缓冲器的有效增益，这可以抑制可编程电容反馈放大器的噪声贡献。在0.18 μ m CMOS工艺制造，建议读出电路实现了3.7 μ Vrms（A加权）输入参考噪声。在与商用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 μ A下的2 V电源，并占用0.25毫米（2）的有效面积。
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 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 A under a 2-V power supply and occupies an active area of 0.25 mm(2).