A self-centering and stiffness-controlled MEMS accelerometer

• Published in: Microsystems & nanoengineering Vol. 10; no. 1; p. 11
• Main Authors: Jin, Yiming, Ma, Zhipeng, Ye, Ziyi, Li, Mingkang, Zheng, Xudong, Jin, Zhonghe
• Format: Journal Article
• Language: English
• Published: England Springer Nature B.V 2024; Nature Publishing Group
• Subjects: Accelerometers; Circuits; Closed loops; Drift; Dynamic models; Electrostatic properties; Microelectromechanical systems; Parallel plates; Stiffness; Temperature effects; Tuning; Electrical and electronic engineering; Sensors
• ISSN: 2055-7434; 2096-1030; 2055-7434
• DOI: 10.1038/s41378-023-00647-4

This paper presents a high-performance MEMS accelerometer with a DC/AC electrostatic stiffness tuning capability based on double-sided parallel plates (DSPPs). DC and AC electrostatic tuning enable the adjustment of the effective stiffness and the calibration of the geometric offset of the proof mass, respectively. A dynamical model of the proposed accelerometer was developed considering both DC/AC electrostatic tuning and the temperature effect. Based on the dynamical model, a self-centering closed loop is proposed for pulling the reference position of the force-to-rebalance (FTR) to the geometric center of DSPP. The self-centering accelerometer operates at the optimal reference position by eliminating the temperature drift of the readout circuit and nulling the net electrostatic tuning forces. The stiffness closed-loop is also incorporated to prevent the pull-in instability of the tuned low-stiffness accelerometer under a dramatic temperature variation. Real-time adjustments of the reference position and the DC tuning voltage are utilized to compensate for the residue temperature drift of the proposed accelerometer. As a result, a novel controlling approach composed of a self-centering closed loop, stiffness-closed loop, and temperature drift compensation is achieved for the accelerometer, realizing a temperature drift coefficient (TDC) of approximately 7 μg/°C and an Allan bias instability of less than 1 μg.