The Application of Parametric Excitation in Resonant MEMS Gyroscopes

Parametric excitation, via electrostatic stiffness modulation, can be exploited in resonant MEMS gyroscopes. In the case of the rate gyroscope parametric excitation may be used to amplify either the response to angular rate. In the more complex mode of operation, known as “rate integrating,” the output of the gyro is angled directly as opposed to angular velocity in the case of rate gyro. In this rate-integrating mode of operation parametric excitation does offer an effective energy control used to initiate and sustain the vibration and minimize damping perturbations. A practical parametric excitation scheme implemented using digital signal processing has been developed for both the rate and rate-integrating gyro. Experimental results are presented demonstrating the benefit of using parametric excitation. By taking advantage of the phase dependence of parametric amplification and the orthogonality of the Coriolis force and quadrature forcing, the response to the applied angular velocity may be parametrically amplified by applying excitation of a particular phase directly to the sensing mode.