FEEDBACK CIRCUIT FOR MICROMACHINED ACCELEROMETER

摘要

An accelerometer comprises a movable electrode between two fixed electrodes to form a differential capacitor. Drivers provide AC drive signals with phase shift of 180 DEG to the fixed electrodes. The movable electrode is coupled through reading circuitry to an output terminal. In response to a sensed acceleration, feedback is provided from the output terminal to one or both drivers to null any AC signal on the movable electrode by modifying the amplitudes of the drive signals and to keep the electrostatic forces between the movable electrode and each of the fixed electrodes equal.