In-Situ Mode-Matching Control for a Single-Chip Horizontal Dual-Axis MEMS Gyroscope Based on Modulating Quadrature Coupling with Silicon Gratings

We experimentally present an in-situ mode-matching control approach for a custom designed single-chip horizontal dual-axis MEMS gyroscope to synchronize the resonant frequencies of the two sense modes to the drive mode simultaneously for the first time. The tuning method is based on the observation of the leaked amplitude in Coriolis channel corresponding to the modulating quadrature coupling by an auxiliary signal outside the sensor bandwidth with dedicated silicon gratings, thus avoiding interfering with the input rotation rate. The proposed solution is validated on an NI-based system connected to the dual-axis MEMS gyroscope with analog readout circuits. The preliminary results show that a mode matching of nearly 8 ppm precision for a resonant frequency of ∼6.8 kHz can be easily attained with a frequency difference stability of 15 mHz. The mechanical gain of Coriolis signal is ∼62-fold increased after mode-matching. The use of silicon gratings for mode-matching technique paves an effective way to build a navigation grade precision monolithic chip horizontal dual-axis MEMS gyroscope in the future.