基于电磁激励的SOI-MEMS谐振式加速度计的闭环检测系统(英文)

Closed-Loop Control System of a SOI-MEMS Resonant Accelerometer with Electromagnetic Excitation

介绍了一种基于电磁激励方式,采用基于绝缘体上硅的微电子机械系统(SOI-MEMS)加工方法制作谐振式加速度计及其闭环控制电路系统.传感器芯片制作采用的是SOI材料(10μm+2μm+290μm),利用MEMS加工工艺制作.当外界z轴方向加速度作用于加速度计时,加速度计的两根"H"型谐振梁因受到弯曲应力而产生谐振频率的漂移,通过检测谐振梁频率的变化标定加速度的大小.电磁激励检测方式有利于加速度计的最终闭环控制.闭环电路控制系统主要由增益放大部分、自动增益控制(AGC)电路缓冲系统和移相器组成.测试结果显示,当有1g重力加速度作用于加速度计,闭环电路可稳定输出检测正弦频率信号58.958 kHz,与开环扫频结果一致.加速度计的"H"型谐振梁空气中检测Q值约为400,灵敏度可达584 Hz/g.

A closed-loop control system with electromagnetic excitation designed for a SOI-MEMS resonant accelerometer is proposed in this paper.The sensor chip is developed by silicon-direct-bonding SOI wafer（10 μm＋2 μm＋290 μm） with MEMS fabrication technology.z-axis acceleration is differentially detected by using two H-style vibrating beams through a frequency shift caused by the inertial force acting as bending stress loading.Frequency change of vibrating beams is used to calibrate acceleration.Electromagnetic excitation and detection are adopted to make the closed-loop control of the sensor easier.The whole closed-loop control system for the accelerometer mainly consists of amplifier,automatic gain control（AGC） circuit,buffer and phase shifter.Testing results show that the accelerometer with the closed-loop system can work stably at 58.958 kHz when 1g z-axis acceleration is applied,which is consistent with the open-loop testing result.Final tests show that the Q-factor of vibrating beam is about 400 in air and the differential sensitivity measured can reach as high as 584 Hz/g.