Apple Inc.
Capacitive Position Sensing for Capacitive Drive MEMS Devices

Abstract:

An apparatus for driving and position sensing in a comb-drive actuator includes a generator, a driver circuit, sensing circuitry, and signal processing circuitry. The generator is configured to apply a sensing-voltage to a first electrode of the comb-drive actuator. The driver circuit is configured to apply a drive-voltage to a second electrode of the comb-drive actuator, having an opposite polarity relative to the first electrode. The sensing circuitry is configured to measure at the second electrode a sensed-waveform resulting from the sensing-voltage applied to the first electrode. The signal processing circuitry is configured to estimate a position of the first electrode relative to the second electrode based on the sensed-waveform.