Mode-matched MEMS Coriolis vibratory gyroscopes: Myth or reality?

The majority of commercial MEMS gyroscopes are operated in a mode-split condition where the drive and sense modes are intentionally mismatched in frequency, thus prioritizing gain stability and allowing for wide bandwidth but often sacrificing the noise density. In mode-matched operation, the gyroscope gain depends on sense-mode Q-factor, which improves the noise and scale-factor of MEMS gyroscopes. The scale-factor and offset stability over environment, however, also depend on the frequency matching, calling for the development of a mode-matching loop. Here we proposed a mode-matching loop which relies on monitoring the Coriolis channel output in response to the quadrature electrode dither. We have experimentally demonstrated an order of magnitude improvement in in-run bias instability and stress sensitivity when the mode-matching loop was employed, demonstrating a path towards mode-matched MEMS gyroscope with low-noise, wide measurement bandwidth, and offset stability over environment.