Sung-ku Kang

A tunable vibratory microgyroscope

Abstract A tunable vibratory microgyroscope has been fabricated by surface-micromachining technology. The 7.5 μm thick polysilicon structural layer is deposited using LPCVD at 625 °C. The resonance frequency in the detection mode is designed to be higher than that in the driving mode so that the gyroscope could be matched to the resonance frequencies by applying an inter-plate d.c. bias. The gyroscope is driven in a resonant state by electrostatic force and the output detected is due to a capacitance change between the plate and the polysilicon electrode. The resonance frequencies of the gyroscope in the driving and detection directions are measured to be 10.48 and 10.93 kHz, respectively. The resonance frequency in the detection direction can be shifted to 10.52 kHz by applying a tuning voltage of 4.0 V. The quality factor and resonance frequency of the detection mode are significantly affected by ambient pressure. The electrical noise equivalent rate of this device is about 0.1 ° s −1 at 10 −2 torr.