Research On Measurement And Control Circuit Technology Of MEMS Push-pull Type Resonant Accelerometer

MEMS resonant accelerometer,as a new type of inertial device for high-precision acceleration measurement,has the advantages of high sensitivity,low power consumption,quasi digital output and so on.It is widely used in national defense,commercial and other fields.In this paper,the push-pull MEMS resonant accelerometer developed by the research group is taken as the research object.According to its structure and working principle,the closed-loop driving circuit and frequency detection circuit of the push-pull MEMS resonant accelerometer are studied,and the performance of the accelerometer is tested.Firstly,the structure design of the push-pull MEMS resonant accelerometer is given.According to the structural characteristics of the resonator,the basic working mode of the accelerometer is introduced,the working principle of electrostatic drive is analyzed,and the ring diode interface circuit with higher precision and better parasitic capacitance suppression is selected.Secondly,two working modes to realize closed-loop drive are studied,self-excited oscillation is selected as the closed-loop phase control method,the transfer function in the AGC loop is derived,and the numerical selection of PI controller proportional and integral coefficients in the case of noise is discussed.The designed closed-loop drive is simulated and analyzed to verify the feasibility and stability of the system.Finally,the advantages and disadvantages of the four methods of digital frequency measurement are compared,the equal precision frequency measurement method is selected as the frequency detection method,and the frequency measurement module is analyzed and designed.Based on the above research,the analog closed-loop drive circuit and the digital open-loop frequency measurement circuit are designed,and the performance test of the push-pull MEMS resonant accelerometer is completed in the laboratory environment.The test results show that within the range of ±1g,the scale factor of the push-pull MEMS resonant accelerometer is204.42Hz/ g,the repeatability of the scale factor is 31.1ppm,and the zero bias stability is0.00801 g.It lays a foundation for the realization of high sensitivity accelerometer and high precision measurement and control circuit.