基于MEMS电容式加速度计的闭环读出电路设计

Design of Closed-Loop Readout Circuit Based on MEMS Capacitive Accelerometer

设计了面向圆片级封装的一种闭环加速度计读出电路。在基于电容式微加速度计结构的读出电路设计中考虑了寄生电容对整个系统的影响。用MATLAB SIMULINK对所设计的读出电路进行了建模仿真。在仿真过程中分析了噪声、圆片级封装与普通封装的寄生参数及实际工艺中流水结构的不对称性的影响并进行了比较。结果表明,所设计传感器及读出电路的非线性误差在量程±20 gn范围内小于0.5%;圆片级封装的稳定时间在2 ms,小于普通封装的稳定时间;基于圆片级封装的对称性梳齿结构的输出电压灵敏度为328 mV/gn。

A closed-loop accelerometer readout circuit for wafer-level packaging is designed.The influence of parasitic capacitance on the whole system is considered in the design of readout circuit based on capacitive microaccelerometer structure.The readout circuit is modeled and simulated by MATLAB SIMULINK.In the process of simulation,the influence of noise,parasitic parameters of wafer-level package and ordinary package and and the asymmetry of flow structure in actual process are analyzed and compared.The results show that the nonlinear error of the designed sensor and readout circuit is less than 0.5%in the range±20 gn;A stable time of 2 ms,for wafer level packaging;An output voltage sensitivity of a symmetrical comb structure based on a wafer-level package is 328 mV/gn.