Non-resonant surface-micromachined z-axis gyroscopes utilizing torsional out-of-plane detection

The paper reports a novel gimbal-type torsional z-axis micromachined gyroscope with a non-resonant actuation scheme. The design concept is based on employing a 2 degrees-of-freedom (2-DOF) drive-mode oscillator to achieve dynamic amplification of oscillations and a flat region in the frequency response. By utilizing dynamic amplification of torsional oscillations in the drive-mode instead of resonance, large oscillation amplitudes of the sensing element is achieved with small actuation amplitudes, providing improved linearity and stability despite parallel-plate actuation. With the flat region in the frequency response, the drive direction amplitude and phase are inherently constant within the same frequency band, while the device operates at resonance in the sense direction for improved sensitivity. Thus, the design concept is expected to overcome the small actuation and sensing capacitance limitations of surface-micromachined gyroscopes, while achieving improved excitation stability and robustness against fabrication imperfections and fluctuations in operating conditions.