MEMS Gyroscope With Less Than 1-deg/h Bias Instability Variation in Temperature Range From −40 °C to 125 °C

We developed a gyroscope with less than 1-deg/h bias instability variation in a temperature range from −40 °C to 125 °C while performing around 4-deg/h bias instability. This stability was achieved by using the stable frequency separation between the drive and sense modes of a Coriolis vibratory gyroscope. To achieve this stability, the mechanical part was designed with a one-sided open frame to mitigate the variation of resonant frequencies caused by thermal stress. At the circuit level, we implemented a self-clocking architecture with a bandpass $\Sigma -\Delta $ analog-to-digital converter to maintain low quantization noise level over the operational temperature range. The fabricated gyroscope demonstrated a 2-Hz variation of frequency separation for an operational frequency of 18.5 kHz in the operational temperature range. At a system level, a bias instability variation of 0.9 deg/h in the temperature range while performing bias instability less than 4.21 deg/h was demonstrated. This low-noise variation is potentially beneficial for applications requiring a Kalman filter, such as GPS-denied navigation systems, that demands a precise and predetermined noise property.