面向MEMS加速度传感器的aF级电容检测电路设计  

Design of aF Level Capacitive Detection Circuit for MEMS Accelerometer

作　　者：覃飞洋 何文正 彭晶晶 元赛飞 尤睿 鲁文帅 QIN Feiyang;HE Wenzheng;PENG Jingjing;YUAN Saifei;YOU Rui;LU Wenshuai(School of Instrument Science and Optoelectronic Engineering,Beijing University of Information Technology;Department of Precision Instruments,Tsinghua University)

机构地区：[1]北京信息科技大学仪器科学与光电工程学院 [2]清华大学精密仪器系

出　　处：《仪表技术与传感器》2024年第12期17-22,共6页Instrument Technique and Sensor

摘　　要：针对MEMS电容式加速度计输出信号弱(fF量级)、易受干扰等问题,设计了一种基于差分载波调制解调方法的高精度电容检测电路,检测下限可达aF量级。该方法采用高频载波调制解调,可有效抑制1/f噪声;采用敏感电容差动检测方式,可抑制共模噪声干扰。采用fF级动态电容输出的商用加速度计表头搭建测试系统,测试结果表明:所设计电路的电容检测下限可达35 aF,等效电容分辨率为2.88 aF/√Hz,本底噪声水平为372μg/√Hz,可满足高精度MEMS加速度计检测需求。This paper designed a high-precision capacitance detection circuit based on a differential carrier modulation and demodulation method aiming at the problems that the output signals of MEMS capacitive accelerometer is weak(fF level)and is susceptible to interference.The limit of capacitance detection can reach to the aF level.A high-frequency carrier modulation and demodulation method was applied to eliminate the 1/f noise.A differential capacitance detection method was utilized to suppress the common-mode noise.The article used a commercial accelerometer head with fF level dynamic capacitor output to build a test system.Experimental results show that the designed circuit exhibited a limit of capacitance detection to 35 aF,an equivalent capacitance resolution of 2.88 aF/√Hz Hz,and a noise floor level of 372μg/√Hz,demonstrating a high-performance capacitor detection capability,meeting the requirements of high-precision MEMS accelerometer detection.

关 键 词：加速度计 电容读出 差分调制 分辨率 aF级精度 

分 类 号：TN492[电子电信—微电子学与固体电子学]