A Stiffness-tunable MEMS Accelerometer with In-operation Drift Compensation

This paper reports a thermal bias drift (TBD) in-operation compensation approach for a stiffness-tunable MEMS accelerometer with the double-sided parallel plate (DSPP) capacitors. To monitor real-time TBD of the proposed accelerometer, an out-of-bandwidth AC signal is used to stimulate the accelerometer. The demodulated response phase which varies linearly with the TBD can be utilized for in-operation calibration. An in-operation compensation of the TBD is proposed in which the calibration phase is controlled to a preset value by adjusting the stiffness tuning voltage of DSPP capacitors. The proposed accelerometer with in-operation drift compensation enables the prevention of pull-in due to temperature drift, achieving a temperature drift coefficient (TDC) of about 0.3 mg/°C and an Allan variance bias instability of about $0.5\ \mu\mathrm{g}$.