微机械电容式加速度计读出电路研究与设计

Research and design of MEMS capacitive accelerometer readout circuit

摘要:

为了提高电容式MEMS加速度计测量精度，设计了一种应用于MEMS加速度计微弱信号读出电路。读出电路由T型阻容网络放大电路、模拟开关解调电路和四阶带通滤波电路组成，通过Multisim软件仿真分析各模块电路原理并确定影响读出电路的主要因素，进一步优化确定元器件最佳参数，最后制作出PCB电路板并开展实验测试，实验结果表明微弱信号检测准确率达90%以上，能很好满足电容式MEMS加速度计微弱信号检测要求，同时该读出电路具有尺寸小、易调节、易于ASIC集成等特点，在微机械仪表的微小电容检测中有较高的实用价值。

Abstract:

In order to improve the measurement accuracy of capacitive Micro Electro Mechanical System （MEMS） accelerometer, a weak signal readout circuit for MEMS accelerometer is designed. The readout circuit is composed of T-type resistance-capacitance network amplifier circuit, analog switch demodulation circuit and fourth-order bandpass filter circuit. The principle of each module circuit is analyzed by Multisim software, the main factors affecting the readout circuit are determined, and the optimum parameters of the components are further optimized. Finally, PCB circuit board is made and tested. The results show that the detection accuracy of weak signal is over 90%, which can satisfy the requirements of capacitive MEMS accelerometer. Meanwhile, the readout circuit has the characteristics of small size, easy adjustment and easy integration of ASIC.