Frequency Modulated Operation in a Silicon MEMS Gyroscope with Quatrefoil Suspension System

Abstract

This paper reports a MEMS Gyroscope based on mechanical frequency modulation. The gyroscope operates by tracking the resonant frequencies of two high-Q degenerate elliptical modes (∼426 kHz) in a vacuum packaged MEMS gyroscope with a novel quatrefoil suspension system, fabricated on a (100) single-crystal silicon substrate. The frequency-based measurement of the input angular rate is realized using two digital phase-locked loops and implementing electrostatic frequency tuning to decrease the frequency split between the two near-degenerate modes from 4 Hz to 0.8 Hz. Measured results demonstrate an angle random walk (ARW) and bias instability (BI) of 0.917 ◦/$\sqrt h $ and 6.7 ◦/h respectively, benchmarking favorably in comparison with other state-of-the-art frequency modulated (FM) gyroscopes.