Analyzing the Impact of Phase Errors in Quadrature Cancellation Techniques for MEMS Capacitive Gyroscopes

Quadrature error in MEMS capacitive gyroscopes can limit the overall sensor performance, therefore many techniques have been proposed to correct for it. These techniques include Synchronous demodulation, Open-loop and Closed-loop cancellation techniques. However, the effect of non-idealities on the effectiveness of these techniques was not reported. And since these techniques involve demodulation and modulation stages, phase errors can greatly impact the cancellation process, and consequently the gyro bias stability and bias over temperature specs. In this work, different quadrature cancellation techniques are presented and analyzed, and closed-form expressions for the effect of phase error on these techniques are derived, highlighting the effect of phase error due to modulation stage and how it can deteriorate the quadrature loop operation. In addition, simulation results verifying the analysis are presented.