Analysis of the self-test characteristics of a micromachined accelerometer

A hybrid micro-accelerometer system consisting of a lateral capacitive silicon micro-acceleration and a CMOS integrated readout circuit is presented. The self-test function of the micromachined accelerometer is realized by electrostatic method. The electrostatic force drives the proof mass to produce an equivalent acceleration. The electrostatic force, pull-in voltage and steady driving displacement are analyzed theoretically. Theoretical analysis is validated by testing the relation between the self-test driving voltage and the output voltage, and discussion about the test results is given. Owing to the error of the processing, the sensing gap between electrodes increases, and the static capacity decreases. Correspondingly, the generated electrostatic force is smaller than the theoretic value, the displacement of electrodes shortens, and the voltage sensitivity is lower than the simulation result.