Ultra-high Q silicon gyroscopes with interchangeable rate and whole angle modes of operation

We report a new family of ultra-high Q silicon MEMS tuning fork gyroscopes demonstrating angle rate and, for the first time, rate integrating (whole angle) operation. The novel mechanical architecture eliminates low frequency in-phase modes and maximizes the Q-factors. A vacuum packaged SOI dual mass gyroscope with a 1.7 kHz operational frequency demonstrated drive- and sense- mode Q-factors of 0.31 and 0.64 million, respectively. A completely symmetric, dynamically balanced quadruple mass gyroscope with a 2.2 kHz operational frequency demonstrated identical drive- and sense-mode Q-factors of 0.45 million. Due to the stiffness and damping symmetry, the new gyroscope can be instrumented to measure the angle of rotation directly, eliminating the bandwidth and dynamic range limitations of conventional MEMS vibratory rate gyroscopes. The technology may enable silicon micromachined devices for inertial guidance applications previously limited to precision-machined quartz hemispherical resonator gyroscopes.