An analog circuit model for drive mode of MEMS vibratory gyroscope

In this paper, an analog circuit model for the drive mode of a two-degree-of-freedom MEMS vibratory gyroscope is presented. This model is implemented on a printed circuit board by analog integrated circuits. To investigate the real behavior of the gyroscope sensor, the cubic stiffness coefficient is considered. This proposed circuit can be a suitable test bench for designers of gyroscope control loops. In other words, one can test and finalize gyroscope control loops before fabricating the gyroscope die. When we come to solve the gyroscope dynamic equations, there are some significantly important terms in response with small amplitudes. To make these signals vivid and noticeable in hardware implementation, the gyroscope coefficients are scaled to be measurable. The frequency response of the drive mode for various excitation signal amplitude is obtained. For large values of AC excitation, the hysteresis loop is appeared in the frequency response of the drive mode, while the frequency response of the proposed circuit model to the small AC excitation is Gaussian-shaped completely. However, the drive mode natural frequency variation versus the AC excitation signal amplitude variation is observed. The drive mode natural frequency increases nonlinearly with increasing the AC excitation signal amplitude. To verify the performance of the proposed analog circuit model, the dynamics equations of the MEMS vibratory gyroscope drive mode are simulated by MATLAB Simulink software. The comparison between the simulation and the experimental results indicates that the results are completely consistent. The proposed analog circuit can be an appropriate choice for presenting the real behavior of the MEMS vibratory gyroscope accurately.