Bandwidth Expansion for Mode-Matched MEMS Gyroscopes Without Any Compensator

Bandwidth performance is critical for MEMS gyroscopes in high-dynamic applications. However, conventional compensator-based bandwidth expansion methods are limited by design complexity and sensitivity to gyroscope parameters. To address these challenges, this article proposes a novel compensator-free bandwidth expansion strategy for mode-matched MEMS gyroscopes. By modeling the sense mode closed-loop system as a unity negative feedback (NFB) system, we identify the forward gain as a critical factor based on the fact that the bandwidth is proportional to the gain crossover frequency. The expansion strategy involves three steps: first, determining the cutoff frequency of the low-pass filter (LPF) in the demodulation stage; second, optimizing the forward gain by the Nyquist stability criterion; and third, tuning controller parameters to ensure optimal flatness across the bandwidth. Simulation and experimental results demonstrate bandwidth expansion from 14 to 191 Hz and 15 to 190 Hz, respectively, without compromising the scale factor (SF) or bias noise. Moreover, the expansion scheme demonstrates strong robustness to variations in gyroscope parameters. Three gyroscope samples with varying drive frequencies and Q-factors achieved bandwidths of 190, 193, and 187 Hz under the same optimization parameters, demonstrating its practicality for engineering applications.