A 7ppm, 6°/hr frequency-output MEMS gyroscope

We report the first frequency-output MEMS gyroscope to achieve <;7 ppm scale factor accuracy and <; 6°/hr bias stability with a 3.24mm² transducer. By implementing continuous-time mode reversal in an FM gyro, the rate signal is modulated away from DC, making the system insensitive to the resonant frequency of the transducer. The scale factor is almost entirely ratiometric, depending primarily on the mechanical angular gain factor of the transducer and the accuracy of the timing reference. Scale factor sensitivity to variations in quality factor, electro-mechanical coupling coefficients, and circuit drift is significantly reduced compared to conventional open-loop and force-rebalance operating modes.