Abstract
This work reports the design, simulation, fabrication, and measurement of MEMS vibratory gyroscopes. The relationship between specification and parameters is also discussed from the viewpoint of the whole system. The first design, Filter-Sensing Mode Gyroscope (FSMG), based on TSMC’s MEMS Platform can reach larger bandwidth with sufficient sensitivity. The theory shows that the parameters in FSMG are not sensitive to the environmental damping coefficient. Moreover, the tuning fork structure in FSMG provides better shock resistance and error reduction. The robustness makes FSMG very suitable for automotive applications. The second design based on an SOI fabrication process is also developed. Ring Coupled Gyroscope (RCG) takes advantages of the symmetric ring structure, while increasing the transduction areas. This design makes the ring structure without increasing its size or reducing its transducer’s gap to achieve satisfactory capacitive coupling coefficient. By adopting the in-plane and n = 3 mode, the resonant frequencies (i.e., driving and sensing modes) of RCG are inherently matched. Therefore, it has great potential for the next generation gyroscopes. The fabricated RCG has the smallest frequency split as ∆f/fres≅0.0096% at the resonant frequency of 135 kHz. The quality factor is about 3000-10000 in vacuum and 30-60 in air, respectively. The PCB for the proposed gyroscope is also designed for control and measurement purpose. The driving loop with AGC is achieved. The measured sensitivity is 2.2 mV/°/s, and the angle random walk is 15.8°/√hr.