A Real-Time Circuit Phase Delay Correction System for MEMS Vibratory Gyroscopes.

Pengfei Xu,Jin Ning,Lu Jia,Guowei Han,Zhiyu Guo,Fuhua Yang,Chaowei Si,Zhenyu Wei

doi:10.3390/mi12050506

Abstract

With the development of the designing and manufacturing level for micro-electromechanical system (MEMS) gyroscopes, the control circuit system has become a key point to determine their internal performance. Nevertheless, the phase delay of electronic components may result in some serious hazards. This study described a real-time circuit phase delay correction system for MEMS vibratory gyroscopes. A detailed theoretical analysis was provided to clarify the influence of circuit phase delay on the in-phase and quadrature (IQ) coupling characteristics and the zero-rate output (ZRO) utilizing a force-to-rebalance (FTR) closed-loop detection and quadrature correction system. By deducing the relationship between the amplitude-frequency, the phase-frequency of the MEMS gyroscope, and the phase relationship of the whole control loop, a real-time correction system was proposed to automatically adjust the phase reference value of the phase-locked loop (PLL) and thus compensate for the real-time circuit phase delay. The experimental results showed that the correction system can accurately measure and compensate the circuit phase delay in real time. Furthermore, the unwanted IQ coupling can be eliminated and the ZRO was decreased by 755% to 0.095°/s. This correction system realized a small angle random walk of 0.978°/√h and a low bias instability of 9.458°/h together with a scale factor nonlinearity of 255 ppm at room temperature. The thermal drift of the ZRO was reduced to 0.0034°/s/°C at a temperature range from −20 to 70 °C.

Highlights

Introduction published maps and institutional affilMicro-electromechanical system (MEMS) gyroscopes, measuring the angular rate motion based on the Coriolis effect [1], have been widely adopted for industrial and consumer applications [2,3] for their small size, high integration, low cost, and low power consumption
We demonstrated a real-time circuit phase delay correction system to compensate the unwanted circuit phase delay for micro-electromechanical system (MEMS) vibratory gyroscopes
[−Cxy A x wd cos( φd ) − k xy A x sin( φd )]. It can be seen from the above derivation that the existence of the circuit phase delay φd leads to the coupling of the in-phase and the quadrature channel (IQ coupling), which introduces an uncontrollable low-frequency noise, leading to a large drift in the zero-rate output (ZRO)