电容式振动传感器谐波失真自检测接口ASIC设计  

Design of Interface ASIC for Capacitive Seismic Sensor with Harmonic Distortion Self-Testing

作　　者：刘晓为[1,2] 尹亮[1] 陈伟平[1,2] 王庆一[1] 周治平[1] 

机构地区：[1]哈尔滨工业大学MEMS中心,哈尔滨150001 [2]微系统与微结构教育部重点实验室,哈尔滨150001

出　　处：《纳米技术与精密工程》2010年第6期537-544,共8页Nanotechnology and Precision Engineering

基　　金：国家高技术研究发展计划(863计划)资助项目(2008AA042201)

摘　　要：为实现电容式振动传感器的谐波失真测量,针对电容式振动传感器表头设计出一种开关电容型接口ASIC芯片,采用相同电极分时复用的方法,从而避免电容敏感与静电力反馈的馈通现象.对传感器敏感电容上下极板与中间质量块间的杂散电容导致的谐波失真进行了原理分析,可知传感器二次谐波与寄生电容成正比,三次谐波与寄生电容无关.提出采用电容阵列补偿、静电力平衡反馈式闭环电路结构进行传感器谐波失真抑制,并基于静电力原理提出一种新的电容式振动传感器谐波失真自检测方法,该方法无需精密振动台,仅需要低失真度电压信号源.实际测试结果显示,谐波失真检测精度可达到-83 dB.ASIC芯片采用2μm CMOS工艺流片,刻度因子为1.2 V/g(g为重力加速度,g=9.8 m/s2),量程为±2g,噪声密度为3×10-6g/(Hz)～(1/2),静态功耗为40 mW.测试结果证明,该电路达到高精度微加速度计系统设计要求,可以应用到地震监测、石油勘探等领域中.In order to implement the harmonic distortion testing of capacitive seismic sensor,a switched-capacitor CMOS interface ASIC chip was designed for closed-loop operation of a capacitive micro-machined seismic sensor,in which time division multiplexing of the same electrode was adpted to avoid the strong feedthrough between capacitance sensing and electrostatic force feedback.Principles for the harmonic distortion caused by stray capacitances between the top and bottom plates of capacitive accelerometer and the middle mass were analyzed,results of which show that the second harmonics of the sensor is proportional to the stray capacitance and the third harmonics is independent of the stray capacitance.More-over,a structure of capacitance array compensation and static force feedback of high loop gain was designed for suppression of harmonic distortion of the sensor.A novel approach to harmonic distortion self-testing of the capacitive micro-machined seismic sensor was put forward,which was based on electrostatic force and only needed a low harmonic distortion voltage source without high quality shake table.The designed ASIC chip was fabricated in a 2 μm CMOS process,which could offer a measured resolution of harmonic distortion of-83 dB,sensitivity of 1.2 V/g（g is the acceleration of gravity,g=9.8 m/s2）,measurement range of ±2g,noise floor of 3×10-6g/（Hz）～（1/2）,and power consumption of 40 mW.Results prove that the circuit presented in this paper has reached the requirement of micro-accelerometer with high performance and can be applied in the fields like seismic monitoring and oil exploration.

关 键 词：振动传感器 谐波失真 开关电容 专用集成电路(ASIC) 

分 类 号：TN492[电子电信—微电子学与固体电子学]