0.25 deg/h Closed-Loop Bulk Acoustic Wave Gyroscope

This paper reports on the design and characterization of a low-noise, wide-bandwidth, mode-matched bulk-acoustic wave (BAW) gyroscope operating in a rotation-rate closed-loop configuration. The high Q (350,000), second-elliptical degenerate modes (4.84 MHz) of a vacuum-packaged (100) single-crystal silicon disk are interfaced with integrated electronics in a force-to-rebalance (FTR) architecture, achieving an angle white noise (AWN) of 0.021 ″/√Hz, an angle random walk (ARW) of 0.017 °/√h, and an Allan deviation of 0.25 °/h in the bias instability (BI) region. By utilizing a relatively low disk polarization voltage of -5 V, the contribution of drive-loop flicker noise, induced by parallel-plate capacitive non-linearity, is significantly reduced. The use of a negative bias voltage, which is internally generated by a new charge pump architecture within the integrated circuit, guarantees that wide tuning and quadrature compensation ranges can still be attained.