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摘要
This paper presents numerical models and experimental investigation of energy loss mechanisms in tuning-fork gyroscopes fabricated on silicon-on-insulator (SOI) wafers. While the numerical model of thermoelastic damping is created according to a thermal-energy method, in which thermoelastic damping is interpreted from thermal perspective and its mathematical expression is derived using a well-defined thermodynamic parameter-entropy, the numerical model of anchor loss is based on a separation-andtransfer method, in which a tuning-fork structure and its substrate are first separated for analysis and then the stress from the clamped regions of the structure is transferred to the substrate for determining the vibration displacement across the clamped regions. The corresponding experimental investigation of energy loss mechanisms in the tuning-fork gyroscopes is consequently conducted. By comparing with the measured highest Quality factor (Q) values, the numerical models of thermoelastic damping and anchor loss are validated. The combination of the numerical models and the experimental measurement sheds important and interesting insight on the achievable Q value of these SOI-based tuning-fork gyroscopes: (1) from the design perspective, thermoelastic damping is the sole dominant loss in the gyroscope structure, given that the anchors are tightly fixed to the substrate; (2) but from the fabrication perspective. anchor loss can vary from negligible to significant, simply because HF etching causes the undercut underneath the anchors to various unpredictable extents. In addition, surface loss, damping from experimental electronics, and the effect of the DC polarization voltage on the measured Q Values are also addressed.
- 出版日期2009-5-21
