Abstract: For MEMS capacitive accelerometer, a driving signal with a DC bias voltage and an AC voltage is usually needed for detecting the variation of capacitance. The maximum inertial signal level for reliable operation is significantly reduced by the electrostatic force caused by the driving signal. The reliable operation ranges of capacitive accelerometer with voltage feedback for quasi-static signal and step signal are investigated. The effect model of driving signal with different bias voltage polarities on the critical acceleration that causes pull-in failure is set up. The results show that the electrostatic force imposes significantly larger restriction on the inertial signal range than that on the quasi-static signal and that the critical signal level of step inertial signal is smaller than that of quasi-static signals by a factor. For double-sided driving with voltage feedback, positive-positive and positive-negative bias voltage configurations may mostly eliminate the pull-in effect caused by the driving signal and increase the reliable operation range, while negative-negative and negative-positive bias voltage configurations maximize the side effects of the driving signal and reduce largely the safe operation range of the device.

Key words: Accelerometer, Bias voltage polarity, Electrostatic forces, Feedback