Research On Control Method Of MEMS Resonant Pressure Sensor

Silicon micro-resonance pressure sensor is a new type of pressure sensor,which has important application value in military and civilian fields.The research object aims at silicon micro-resonance pressure sensor,driving circuit technology and high-precision frequency measurement technology.And the test prototype is produced.(1)The dynamic model of silicon micro-resonance pressure sensor is given.The basic working principle is analyzed.According to the structure of the resonator,the piezoresistive detection mode and the derivation formula and simulation model are designed.The system frame design of closed-loop control of pressure sensor is given.(2)The working principles of the phase-locked loop and automatic gain control circuit are discussed in detail.The closed-loop drive circuit of the pressure sensor based on phase-locked and automatic gain control is designed.The simulation results by Simulink of the closed-loop drive system show that the system meets the design requirements.(3)For the dynamic characteristics of the closed-loop control of the resonant pressure sensor,the system bandwidth test scheme is designed to realize the model simulation of the scheme.A switching circuit for the loop filter is given to realize switching of different bandwidth circuits and shorten the tracking lock time of the phase locked loop.(4)For the frequency measurement requirements of the resonant pressure sensor,the system architecture of FPGA+STM32 is selected based on multi-channel phase shift counting method to complete the corresponding algorithm simulation and hardware circuit design,and the developed frequency measurement module is tested.The result shows that the frequency error is less than 0.2mHz with the 1Hz sampling rate.(5)Under the test conditions of 20kPa~120kPa range,the scale factor of the pressure sensor is 16.5Hz/kPa,the scale factor stability is 51.7ppm,the hysteresis of the scale factor nonlinearity and the forward and reverse stroke are 0.015% and 74 ppm.Totally,the research in this paper provides theoretical support and practical circuit scheme for the system of silicon micro-resonance pressure sensor,which lays a foundation for further research.