A discrete-time self-clocking complex electromechanical ƩΔM gyroscope with quadrature error cancellation

Abstract

In this work, a new self-clocking electromechanical sigma-delta modulator (ƩΔM) quadrature error cancellation scheme for MEMS mode-matching gyroscopes is presented. The proposed techniques allow to decompose the gyroscope sense mode into in- and quadrature-phase signals and process it with two high-order sigma-delta control loops, achieving efficient noise shaping and error suppression. Furthermore, the system was designed with a self-clocking calibration scheme to provide temperature-independent turn-on bias output. Simulation results proved its robustness, a significant improvement for linearity and achieving over 80 dB attenuation of quadrature error. The hardware implementation comprising a discrete interface circuit and a wheel gyroscope was demonstrated. Measurement results validate the inherent loop quadrature cancellation scheme and demonstrate a sub-1°/hr bias instability (BI), with 5.5X and 3X improvement of BI and angle random walk (ARW) compared with a conventional single-loop ƩΔM gyroscope system. Combined with real-time self-clocking control, it yields an improvement of turn on bias error (1800s) and output linearity, achieving 1°/h and 0.021 %, respectively.