An automatic mode matching system for a high Q-factor MEMS gyroscope using a decoupled perturbation signal

This paper reports a closed-loop controller system developed for in-run automatic matching of the drive and sense mode resonance frequencies of a MEMS gyroscope with a high quality factor (Q). This is achieved by injecting a perturbation signal to the quadrature cancellation loop, while keeping it decoupled from the angular rate control loop. The new controller is implemented in a CMOS ASIC together with the other sensor control loops, and it is verified to maintain matched-mode state under changing environmental conditions. The system reduces the overall output noise of the tested MEMS gyroscope by a factor of 6; truly reaching down to the thermo-mechanical noise floor of 0.4 (°/hr)/Hz^1/2.