Analysis of the Scale Factor Nonlinearity of MEMS Differential Silicon Resonant Accelerometer Caused by the DETF’s Force-Frequency Nonlinear Characteristic

Abstract

The scale factor nonlinearity of MEMS differential silicon resonant accelerometer(DSRA) structure is mainly due to the force-frequency nonlinear characteristic of DETF. This paper presents a detailed analysis of the relationship between the structural parameters, measurement range and the scale factor nonlinearity, which will provide a reference for the parameter design of DETF and overall structure. The inherent force-frequency nonlinearity of DETFs is analyzed, and the effects of structural parameters of DETF and axial force on nonlinearity of frequency variation are revealed. Combining the working principle of MEMS DSRA introduced first, the scale factor nonlinearity is studied. The results show that the structural parameters of the proof mass (determines the conversion between acceleration and inertial force), the support mechanism and the lever mechanism (determines the transfer coefficient of inertial force), and the DETF (determines the inherent force-frequency nonlinearity and affect the transfer coefficient of inertial force), as well as the measurement range, can all affect the scale factor nonlinearity. Moreover, the scale factor nonlinearity is directly proportional to the square of the measurement range and the square of the nominal scale factor, and inversely proportional to the square of the natural frequency of DETF. The finite element simulation is carried out, and the simulation results are in good agreement with the theoretical analysis values. Finally, the experiment on the scale factor nonlinearity of a prototype is carried out. The measured scale factor nonlinearity of the prototype is 1994.09ppm, which is consistent with the theoretical analysis value of 1737.30ppm.