A 0.1 DEG/H Module-Level Silicon Mems Rate Integrating Gyroscope Using Virtually Rotated Donut-Mass Structure and Demonstration of the Earth's Rotation Detection

This paper presents the first silicon MEMS rate integrating gyroscope (RIG) module capable of detecting the Earth's rotation directly in angle output. The new 5-cm module includes a high frequency if = 11.4 kHz) donut-mass gyroscope (DMG) resonator sealed in vacuum package, a low-noise analog front-end (AFE) circuit, and a high-speed digital microcontroller. The overall S/N is improved by > 50 times, which enables precise and stable controls of frequency, energy, quadrature and angle for the DMG resonator. The angle control of virtual rotation (VR) is applied at a constant rate of 135 deg/s, which eliminates the low-rate threshold in the whole angle (WA) operation. Using the VR, the mechanical frequency asymmetry (Δf) is identified and electrically reduced to Δf/f < 2 ppm. After the removal of VR linear component, the angle output is digitally corrected by modeling and subtraction of the angle dependent bias (ADB). The final angle error is limited by electronics noise, which is 0.01 deg rms at an output data rate (ODR) of 50 Hz. The Allan variance analysis is directly applied to the angle data, which reveals a drift performance reaching 0.1 deg/h at average time of 90 s. Detection of the horizontal Earth's rotation of + 12.4 and -12.4 deg/h at azimuth north and south is confirmed.