A Mode-Matched Silicon-Yaw Tuning-Fork Gyroscope With Subdegree-Per-Hour Allan Deviation Bias Instability

• Published in: Journal of microelectromechanical systems 2008-12, Vol.17 (6), p.1526-1536
• Main Authors: Zaman, M.F., Sharma, A., Zhili Hao, Ayazi, F.
• Format: Article
• Language: English
• Subjects: Bias; Crystallization; Deviation; Devices; Etching; Exact sciences and technology; Fabrication; Frequency; Gyroscopes; Instability; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Measurements common to several branches of physics and astronomy; Mechanical instruments, equipment and techniques; Metrology, measurements and laboratory procedures; Micromechanical devices and systems; Mode-matching; Noise; Noise measurement; Physics; Prototypes; Resonance; Silicon on insulator technology; Silicon substrates; silicon-on-insulator (SOI); Stability; tuning fork; Velocity, acceleration and rotation; vibratory microgyroscope
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2008.2004794

In this paper, we report on the design, fabrication, and characterization of an in-plane mode-matched tuning-fork gyroscope (M 2 -TFG). The M 2 -TFG uses two high-quality-factor (Q) resonant flexural modes of a single crystalline silicon mi- crostructure to detect angular rate about the normal axis. Operating the device under mode-matched condition, i.e., zero-hertz frequency split between drive and sense modes, enables a Q -factor mechanical amplification in the rate sensitivity and also improves the overall noise floor and bias stability of the device. The M 2 -TFG is fabricated on a silicon-on-insulator substrate using a combination of device and handle-layer silicon etching that precludes the need for any release openings on the proof-mass, thereby maximizing the mass per unit area. Experimental data indicate subdegree-per-hour Brownian noise floor with a measured Allan deviation bias instability of 0.15deg /hr for a 60-mum-thick 1.5 mm X 1.7 mm footprint M 2 -TFG prototype. The gyroscope exhibits an open-loop rate sensitivity of approximately 83 mV/deg/s in vacuum. [2007-0100].