Eigenmode operation as a quadrature error cancellation technique for piezoelectric resonant gyroscopes

This paper presents a quadrature error cancellation technique based on the virtual alignment of the gyroscope excitation and readout electrodes to the actual direction of vibration mode shapes in the presence of fabrication non-idealities. The proposed method which is herein referred to as eigenmode operation, enables modal alignment of all-piezoelectric resonant gyroscopes and along with dynamic frequency matching via displacement feedback obviates the need for submicron capacitive gaps and relatively large DC voltages that are otherwise required for electrostatic mode matching. We demonstrate gyroscopic operation of a 3.1 MHz AlN-on-silicon annulus resonator, which utilizes a pair of high-Q degenerate in-plane vibration modes. The piezoelectric gyroscope shows a large operation bandwidth of ~150 Hz with a scale factor of 1.6 nA/°/s while operating in air, which greatly relaxes packaging requirements. Eigenmode operation results in ~35 dB reduction of the quadrature error at resonance.