Effects of bias voltage polarity on differential capacitive sensitive devices

Abstract For capacitive sensing, a driving signal with a dc bias voltage and an ac voltage is usually necessary for the measurement of capacitance. The electrostatic forces caused by the driving signal on the mechanical capacitor may interfere significantly with the measurement and the normal operation of the devices. In this paper, quantitative analyses on the effects of driving signal with different bias voltage polarities are made for double-sided driving and double-sided driving with voltage feedback. For double-sided driving, the effects of the dc bias voltage with different polarities on devices are the same. For double-sided driving with voltage feedback, positive–positive and positive–negative bias voltage configurations may improve the measurement linearity of the device and mostly eliminate the pull-in effect caused by the driving signal, 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.