Sub-Deg-per-Hour Edge-Anchored Bulk Acoustic Wave Micromachined Disk Gyroscope

• Published in: Journal of microelectromechanical systems 2021-12, Vol.30 (6), p.836-842
• Main Authors: Parajuli, Madan, Sobreviela, Guillermo, Pandit, Milind, Zhang, Hemin, Seshia, Ashwin A.
• Format: Article
• Language: English
• Subjects: Acoustic waves; Acoustics; Bulk acoustic wave devices; bulk acoustic wave mode; Gyroscopes; MEMS; Microelectromechanical systems; Micromachining; mode matching; Mode matching methods; Random walk; Resonant frequency; Silicon substrates; Single crystals; Tuning
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2021.3107941

This paper reports on the experimental characterization of a vacuum packaged bulk acoustic wave disk gyroscope with T-shape anchors fabricated on a (100) single-crystal silicon substrate. Improvements in key device performance parameters are achieved by implementing mode matching using electrostatic frequency tuning to decrease the frequency split between two near-degenerate bulk acoustic modes from 4 Hz to 0.4 Hz. Gyroscopic operation is demonstrated by driving one of the secondary degenerate elliptical modes while sensing the response in the other elliptical mode, both demonstrating quality factors exceeding 1 million at an operating frequency of \sim 976 kHz. As a result, the mechanical sensitivity of the gyroscope is improved by a factor of 7.76 times for near mode-matched operation relative to the case with no tuning of the frequency spacing between the modes. Additionally, the angle random walk and bias instability were improved from 0.042~^{\circ }/{\sqrt {h}} to 0.037~^{\circ }/{\sqrt {h}} and 1.65~^{\circ } /h to 0.95~^{\circ } /h respectively, benchmarking favorably with respect to the state-of-the-art of BAW disk gyroscopes. [2021-0151]