Research and Analysis of Bias Voltage on Variable-Capacitance Micro-mechanical Accelerometer

Alternative electric driving signal with a dc bias voltage are to be added to the fixed pole plate commonly to detect the variation of capacitance of variable-capacitance MEMS accelerometer. The electrostatic forces caused by bias voltage may interfere significantly with the measurement of the accelerometer and the reliable operation of the devices. The effects of electric testing signal with different bias voltage polarities on the reliable operation condition are quantitatively analyzed when an acceleration signal is applied on the capacitive accelerometer. A series of alternative different curves are acquired. It is found that the feedback is negative for positive-positive and positive-negative bias voltage configurations, and the reliable operation ranges for positive-negative is the strongest when it is positive-positive bias voltage configuration. The feedback is positive for negative-negative and negative-positive bias voltage configurations, and the reliable operation ranges for negative-positive bias voltage configurations are the weakest. This work will provide a necessary theoretic foundation for the further optimization design of variable-capacitance micromechanical accelerometer.