In-run Mode-Matching of MEMS Gyroscopes based on Power Symmetry of Readout Signal in Sense Mode

This paper presents an in-run mode-matching method for MEMS gyroscopes based on the power symmetry between the sideband signals in the sense mode. The method takes advantage of the power symmetry of both the noise and the Coriolis response within the upper sideband (USB) and the lower sideband (LSB) of the driving frequency. The power difference is taken as a mismatch detection and is fed to the mode-matching controller, which regulates the tuning electrodes. During the matching control, the history of the estimated mode order is recorded to adaptively tune the controller gain, speeding up the tracking process and reducing the steady ripples. The experiments exhibited that the frequency loop could converge to the steady-state within a reasonable time and with 0.28 Hz peak-peak fluctuation. By the mode-matching, the scale factor of the gyroscope under test was boosted by ten times; the angle random walk was enhanced from 8.13 deg/h/sqrt(Hz) to 1.99 deg/h/sqrt(Hz); the bias instability was improved from 2.09 deg/h to 1.12 deg/h. The method proposed in this paper can be implemented with a general platform that MEMS gyroscopes usually utilize.