A Decoupling Design Based on Differential-Mode Cancellation and Common-Mode Superposition for High-Shock Triaxial MEMS Accelerometer

To address the severe transverse coupling issue of missile-borne triaxial MEMS accelerometers under ultra-high shock in hard target precision strike systems, this paper innovatively proposes a differential-mode cancellation and common-mode superposition decoupling method for the design and implementation of a high-shock triaxial MEMS accelerometer. Two symmetric z-axis MEMS sensing units are designed along the diagonal of a square silicon wafer. By utilizing the differential response characteristics of this structure to transverse impacts, the outputs of the two MEMS sensing units are superimposed to cancel out transverse coupling while doubling the z-axis impact signal, thereby decoupling the measured signal from transverse disturbances. Simulation results indicate that within the range of 1.0×10⁵g transverse impact excitation, the transverse sensitivity of the z-axis sensing unit in the triaxial MEMS accelerometer chip is nearly ideal, approaching zero. With a 5V input, the z-axis axial sensitivity of the z-axis sensing unit reaches 0.72μV/g within the 1.0×10⁵g range; under the same input conditions, the x-axis and y-axis sensitivities within a 5.0×10⁴ g range are 1.03μV/g. Furthermore, the design exhibits high linearity and high natural frequency. Process simulations further verify the feasibility of fabricating the triaxial MEMS chip. This study lays a theoretical and technical foundation for miniaturized, intelligent, and low-coupling high-shock measurement under extreme environmental conditions involving high impacts.