A 5 V MEMS gyroscope with 3 aF/°/s sensitivity, 0.6 °/√hr mechanical noise and drive-sense crosstalk minimization

A MEMS bulk micromachined vibratory gyroscope is designed and fabricated in a commercial and low-cost SOI technology — MEMSCAP SOIMUMPs. The device was carefully designed to mitigate micro-fabrication limitations, while achieving high performance. Theoretical analysis of the drive and sense modes was performed in order to reduce the crosstalk between them, while still using a simple gyro structure. The device was simulated using COMSOL taking into account the anisotropic elastic properties of the ‘100’ single-crystalline silicon device layer for added accuracy. The gyroscope operates at 35 kHz with a 5 V DC bias voltage. The relatively low bias voltage leads to significant simplifications in the design of the biasing circuitry, and results in lower power consumption and electrical noise, while ensuring compatibility with standard integrated circuits technologies. The device exhibits a simulated rate sensitivity of ∼ 3 aF/°/s, and its theoretical mechanical noise is calculated to be 0.6 °/√hr. Measurements show a resonance frequency of 27.5 kHz and a quality factor of 120,000 at a 10 mTorr level of vacuum.