Bias thermal stability improvement of MEMS gyroscope with quadrature motion correction and temperature self-sensing compensation

Bias thermal stability of microelectromechanical system (MEMS) gyroscope is a significant performance parameter for industrial and tactical applications. The quadrature coupling motion and demodulation phase error are two main sources of bias drift. This work presents a MEMS tuning fork gyroscope with dedicated electrostatic correction combs finger structure that can be implemented to suppress the quadrature motion. By utilising a closed-loop control for the coupling stiffness, the temperature variation of quadrature motion achieves >260 times of magnitude reduction, resulting in the thermal bias drift decreased from 0.98 to 0.18 degrees/s with 5.4 times improvement over the temperature from -40 to 60 degrees C. The results indicate that the variation of the quadrature motion is the dominant factor that determines the temperature bias drift of the custom-designed gyroscope. The compensated bias stability (1 sigma) is measured to be similar to 8.6 degrees/h by using temperature self-sensing compensation technique over the whole temperature operating range, which demonstrates a considerably competitive result for the tactical-grade MEMS gyroscope.