0.25 deg/h Closed-Loop Bulk Acoustic Wave Gyroscope
Diego Emilio Serrano, Amir Rahafrooz, Ronald Lipka, Duane Younkin, Kieran Nunan, John English, Chihchuan Chen, Ryan Hennessy, Yaesuk Jeong, E.N. Ivanov, Dan M. Sullivan, Ijaz H. Jafri
Abstract
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.