Ratio-metric readout technique for MEMS gyroscopes with force feedback

This paper presents a ratio-metric readout technique for force-feedback gyroscopes that achieves a precise scale factor. The drive mode self-oscillation loop is modified to continuously estimate the scale factor to track and reject changes of the drive mode velocity and proof mass voltage. Experiments demonstrate a twenty-fold reduction of scale factor variations and the suppression of the turn-on transient. The device achieves an angle random walk of 5.3 mdeg/rt-s and a bias stability of 3 deg/hr.