差分电容硅微加速度计检测电路研究

针对硅微加速度计中微小差分电容检测,提出了一种基于调制解调方法的闭环检测电路,介绍了该闭环检测系统的原理框图和实现途径。分析了基于单路载波的前置电容-电压( C-V)转换电路,证明了基于相关芯片的解调方法的有效性,其解调效率仅对开环输出有影响；基于双路反馈电路的静电力平衡回路有效提高该检测系统的线性度。结合硅微加速度计参数和电路设计参数,对加速度计系统进行了仿真,仿真结果显示系统稳定,刻度系数为0.9 V/gn 左右,带宽700 Hz左右。结合表头进行的精密转台实验结果表明该加速度计系统刻度系数0.88 V/gn,量程可达±13 gn。

Research of Detective Circuit for Differential Capacitive Silicon Micro accelerometer

A close-loop detective circuit based on modulation and demodulation is introduced,for detection on micro differential capacitance of silicon micro accelerometer. The principal configuration and the approach are presented. A prepositioned capacitance-to-voltage circuit based on single carrier wave is analyzed,and the validity of the de-modulation approach which is based on correlative chip is proved. The electrostatic rebalance circuit based on feed-back circuits advances the linearity of the system. The Simulink model of the closed-loop system is established with the parameters of the silicon micro accelerometer and the circuits,the results show that the systems stable,and the scale factor is about 0.9 V/gn,with the bandwidth 700 Hz. The circuits presented in this paper are tested on a pre-cision roller with a differential MEMS accelerometer. The test results show that the scale factor of the system is 0.88 V/gn and the measuring range of the accelerometer is ±13 gn.