In order to explore the influence of nonlinear stiffness on resonant pressure sensor and its measurement and control system

a DC AGC closed-loop self excitation model based on nonlinear resonator is established

and the average method is used to solve the model.The simulation model of the closed-loop self-excited system is built in SIMULINK to verify the solution result of the average method and to study the influence of the nonlinear stiffness on the system performance.The natural frequency and nonlinear coefficient of the actual pressure sensor are measured by the method of open-loop sweep and linear fitting.The simulation results show that the solution results of the closed-loop self-excited model based on the average method are closed to the simulation results.The nonlinear stiffness has a very weak impact on the frequency stability of the closed-loop self-excited system

but it will make the dynamic performance of the system worse

thus increasing the difficulty of the closed-loop control.Too large nonlinear coefficient will reduce the sensitivity of the sensor and increase the nonlinearity of the sensor.In the design of sensor chip

the nonlinear stiffness should be reduced as much as possible.