Background calibrated MEMS gyroscope

Abstract

Background calibration is used to reduce three dominant error sources in MEMS gyroscopes over manufacturing variations, temperature, and aging. (1) Measuring the ratio of the change in the oscillation frequency to a calibration signal in the drive channel cancels scale factor errors and drift. (2) Tracking of the velocity-force phase relationship suppresses leakage of the quadrature error into the rate output. (3) Continuous monitoring of the drive signal is employed to reduce errors that are in-phase with the Coriolis signal including anisotropic damping and electrical feedthrough. In combination, the three error cancellation techniques reduce the Allan Variance of an experimental device from 6.6deg/hr to 1deg/hr at 400s averaging time and from 5.7deg/hr to 2deg/hr at 3200s. The temperature sensitivity of the bias decreases from 32mdeg/s/C to 8mdeg/s/C. Scale factor variations over 12 days are reduced from 547ppm p-p to 23ppm p-p, and temperature coefficient of the scale factor is reduced from 560ppm/C to 4ppm/C at room temperature.