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

摘要

A closed-loop control system designed for a SOI-MEMS resonant accelerometer is proposed in this paper. The sensor chip was developed by silicon-direct-bonding SOI wafer (10+2+290 um) 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. The electromagnetically excitation and detection is adopted to make the closed-loop control of the sensor easier. The whole closed-loop control system designed 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 stable at the frequency of 58.958 kHz when 1g z-axis acceleration is applied which is consistent with the open-loop testing.