A Microgyroscope With Piezoresistance for Both High-Performance Coriolis-Effect Detection and Seesaw-Like Vibration Control

• Published in: Journal of microelectromechanical systems 2006-12, Vol.15 (6), p.1698-1707
• Main Authors: Li, Xinxin, Chen, Xuemeng, Song, Zhaohui, Dong, Peitao, Wang, Yuelin, Jiao, Jiwei, Yang, Heng
• Format: Article
• Language: English
• Subjects: Axially stressed piezoresistance; Control systems; Control theory; Detection; Drift; Exact sciences and technology; Feedback loop; Feedback loops; four-terminal transverse piezoresistance; Gyroscopes; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Measurements common to several branches of physics and astronomy; Mechanical instruments, equipment and techniques; Metrology, measurements and laboratory procedures; micromachined gyroscopes; Micromachining; Micromechanical devices and systems; Monitoring; on-chip compensation for temperature drift; Physics; Piezoresistance; Piezoresistive devices; Resonant frequencies; Resonant frequency; Temperature sensors; Tracking loops; Velocity, acceleration and rotation; Vibration control
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2006.879713

A novel piezoresistive scheme is proposed to solve the problem of piezoresistive gyros in terms of low-sensitivity and high-temperature drift. Based on the piezoresistive scheme, a micromachined vibratory gyroscope is developed. By using axially stressed piezoresistive tiny-beams, piezoresistive detection to Coriolis-acceleration can be realized with both high sensitivity and high resonant frequency, i.e., high gyro operation frequency. Thanks to the high piezoresistive sensitivity, precise frequency matching between the driving and detecting modes is unnecessary. Another four-terminal transverse piezoresistive element is used to monitor and stabilize the amplitude of the seesaw-like torsional vibration through a feedback loop. With the same feedback loop, temperature drift of the piezoresistive angular-rate sensing signal can be on-chip compensated, as the transverse piezoresistance tracks the temperature drift of the angular-rate sensing piezoresistors. The gyro is designed and fabricated by bulk micromachining. Measurement results verify the proposed piezoresistive gyro scheme and show noise-limited angular-rate resolution of 0.33deg/s for plusmn300deg/s range. Considering the mature fabrication technology and simple signal-readout for piezoresistive sensors, the piezoresistive microgyros are promising for low-cost applications