一种用于MEMS陀螺的高精度电容读出电路的设计  

Improvement of MEMS Gyroscope Interface Circuit in 0.5 μm CMOS Technics

作　　者：陈方[1] 常洪龙[1] 苑伟政[1] 赵海涛[1] 

机构地区：[1]西北工业大学微/纳米系统陕西省重点实验室,西安710072

出　　处：《传感技术学报》2010年第11期1560-1564,共5页Chinese Journal of Sensors and Actuators

基　　金："863"国家高技术研究发展计划资助(2009AA04Z320)

摘　　要：针对电容式MEMS陀螺,设计了一种高精度CMOS接口读出电路。从理论上分析了接口寄生电容、器件的不匹配对接口电路的影响,采用连续时间电压读出方式的检测方法,设计了一款带有输入输出共模反馈的低噪声全差分电荷运算放大器,输入输出共模电压稳定在2.5V,输入端的噪声电压为9nV。载波调制技术用来消除低频闪烁噪声。在Cadence中对设计的接口电路进行仿真分析,并采用PCB电路板进行了实验。结果显示所提出的接口电路不仅消除了大部分寄生电容的影响,抑制了大部分的耦合信号和噪声信号,而且减小了由于器件的不匹配产生的失调电压对电容分辨率的影响,电路Cadence仿真的电容分辨率可达0.13aF/（Hz）~1/2,能满足惯导级的需求。A high precision CMOS interface readout circuit for a capacitive MEMS gyroscope is designed.the influences of the noise and mismatch to the capacitive readout circuit are analyzed theoretically in detail.Based on a continuous time voltage sensing topology,a low-noise charge sensitive amplifier with input and output common feedback circuit is designed,which the input and output common voltage is 2.5 V,and the input noise floor of the amplifier is 9 nV.the carrier wave modulation technique is used to eliminated the flicker noise,the designed interface circuit was simulated in Cadence and an experimental PCB circuit was made accordingly.The result shows that it can not only remove the impacts of most parasitic capacitances and restrain the noise coupling signals,but also reduce the impacts of offset voltage that comes from mismatch on capacitive resolution,the simulation shows that its capacitance resolution is 0.13 aF（Hz）~1/2,can satisfied the requirements of navigation-grade and the requirements of navigation-grade.

关 键 词：MEMS陀螺 高精度 电容分辨率 CMOS 

分 类 号：TH7[机械工程—仪器科学与技术] V241.5[机械工程—精密仪器及机械]