Dual-axis microgyroscope with closed-loop detection

A dual-axis microgyroscope is fabricated by a surface micromachining process. A 7.0 /spl mu/m-thick polysilicon layer deposited by LPCVD is used for the vibrating structure. We report the closed-loop rate detection of a microgyroscope based on the rotational vibration of the four plates. In particular, the structure utilizes a simple force-balancing torsional torque which does not need another top electrode layer to reduce the intrinsic nonlinearity of a capacitance-type sensor. The gyroscope is tested in a high vacuum chamber for a high Q-factor with hybrid signal-conditioning integrated circuit. The experiment resulted in a noise equivalent signal of 0.1 deg/sec.