CAPACITIVE SENSE FEEDBACK CONTROL FOR MEMS BEAM STEERING MIRRORS

This paper describes a feedback control system for a MEMS dual-axis scanner, which consists of two single-axis torsional mirrors. The mirror position is measured electronically with the sense capacitors and the EAM technique. The feedback system provides electronic damping and improves the dynamic performance of the high Q (~50) mirrors. Closed-loop controlled device achieves 400µs settling time. Due to the feed-through, drive signal mixes with the sense and limits the control bandwidth. Band-pass filtering and pseudo-differential sense attenuates the feed-through in the sense circuit.

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