Effect of circuit phase delay on bias stability of MEMS gyroscope under force rebalance detection and self-compensation method

Abstract

Bias stability is an important performance indicator for MEMS gyroscopes. In this paper, a gyroscope zero rate output (ZRO) model under force-to-rebalance (FTR) closed-loop detection is presented, and the effect of circuit phase delay and various noises on the ZRO is analyzed. Based on the fact that the two feedback forces in the FTR system are insensitive to the phase delay of the sense mode, while they are sensitive to the phase delay of the drive mode, a method for quickly calculating the circuit phase delay is proposed, and an all-pass filter is used to realize one-time automatic compensation for the phase delay in the drive mode. The control system is implemented with an FPGA. The experimental results show that this method can be used to accurately calculate the circuit phase delay and that phase compensation can be used to effectively reduce the effect of quadrature error on ZRO. This technique provides bias instability and angle random walk performances of 0.338° h−1 and 0.061 ° (√h)−1, respectively. In addition, the sensitivity of ZRO to temperature at 0 °C to 70 °C has reached 0.001°/s/°C.