An approach for increasing drive-mode bandwidth of MEMS vibratory gyroscopes

Abstract—The limitations of the photolithography-based micromachining technologies defines the upper-bound on the performance and robustness of micromachined gyroscopes. Con-ventional gyroscope designs based on matching (or near-matching) the drive and sense modes are extremely sensitive to variations in oscillatory system parameters that shift the natural frequen-cies and introduce quadrature errors. Nonconventional design concepts have been reported that increase bandwidth to improve robustness, but with the expense of response gain reduction. This paper presents a new approach that may yield robust vibratory MEMS gyroscopes with better gain characteristics while retaining the wide bandwidth. The approach is based on utilizing multiple drive-mode oscillators with incrementally spaced resonance fre-quencies to achieve wide-bandwidth response in the drive-mode, leading to improved robustness to structural and thermal pa-rameter fluctuations. Enhanced mode-decoupling is achieved by distributing the linear drive-mode oscillators radially and symmetrically, to form a multidirectional linear drive-mode and a torsional sense-mode; minimizing quadrature error and zero-rate output. The approach has been implemented on bulk-microma-chined prototypes fabricated in a silicon-on-insulator (SOI)-based process, and experimentally demonstrated. [1285] Index Terms—Inertial sensors, micromachined gyroscopes, MEMS, rate sensors. I