Distributed-mass micromachined gyroscopes: Demonstration of drive-mode bandwidth enhancement

The limitations of the photolithography-based micromachining technologies defines the upper-bound on the performance and robustness of micromachined gyroscopes. The mode-matching problem and the quadrature error due to the resulting fabrication imperfections are the two major challenges in MEMS gyroscope design. This paper presents a novel micromachined z-axis rate gyroscope with multidirectional drive-mode, that increases the drive-mode bandwidth for relaxing mode-matching requirement, and completely decouples the drive and sense modes. By utilizing multiple drive-mode oscillators with incrementally spaced resonance frequencies, wide-bandwidth response is achieved in the drive-mode, leading to reduced sensitivity to structural and thermal parameter fluctuations. Quadrature error and zero-rate-output are also minimized, due to the enhanced decoupling of multi-directional linear drive-mode and the torsional sense-mode. Bulk-micromachined prototypes have been fabricated in a one-mask SOI-based process, and experimentally characterized.