MEMS Pressure Sensor And Its Anti-jamming Design

The research and development of high-performance MEMS sensors are emphasized in the 14th Five-Year Plan.In view of temperature drift and time drift in traditional silicon-based MEMS pressure sensor.In this article,the structure of MEMS pressure sensor chip is designed based on SNR theory and anti-interference.The combination of constant temperature control and constant current source correction significantly improves performance.The main research contents of this paper are as follows:Firstly,the working principle of pressure sensor based on Wheatstone bridge structure is analyzed theoretically.Then briefly introduce the causes of temperature drift and time drift of sensors.A variety of pressure sensor structures are designed by ANSYS simulation.Combined with the noise correlation model,the sensor noise and SNR are calculated and analyzed theoretically.Then part of a variety of sensors are manufactured and encapsulated with the standard MEMS processing technology.Secondly,the hardware circuit and software design based on MEMS pressure sensor are completed.This system mainly includes pressure signal measurement function,constant temperature compensation control function and time drift constant current source correction function.Among them,integral separation PID algorithm is adopted by the constant temperature control part.Compared with the traditional PID algorithm,it can reduce the temperature oscillation.The AD5420 adjustable current source is used for self-correction of constant current source,simulating the change of air pressure by changing the current.It can recalibrate the output characteristic curve after sensor drift and reduce the measurement error after sensor drift.Then,an experimental platform was built and the sensor was tested.It was found that the sensitivity of pressure sensor was 0.046 mV/(V·k Pa).In the temperature compensation experiment,the thermal zero shift stabilized from-0.0115?0.0652%FS/? before constant temperature compensation to-0.00161?0.00788%FS/? after constant temperature compensation,and the thermal sensitivity shift was also stabilized from -0.118?-0.073%FS/? to-0.00193?0.01528%FS/?.Under constant temperature condition,the prediction error of sensor before and after self-correction decreases from -3.436-0.875 kPa to-2.086-1.765 kPa,and the full range of prediction error decreases from 4.311 kPa to 3.851 kPa.Finally,the output signal measurement and noise test are carried out for each structural sensor.It is necessary to eliminate the external interference as much as possible because of the little noise.So the noise measurement experiment requires higher requirements on the power supply and measuring device.The SNR is calculated after the measured data.It shows that the difference between SNR measured by experiment and theoretical value is in the range of -19.25% to 2.89%.It is proved that the sensor SNR is related to the structure.Under the constant voltage source input condition,the SNR of the sensor increases with the increase of the number of fold turns of the pressure sensitive element,and increases first and then decreases with the increase of the length of the pressure sensitive element.In general,the SNR of the sensor reaches the maximum value when the length of the pressure-sensitive element is about 125?m,and only the SNR of the single-strip sensor is slightly higher when the length is about 75?m than 125?m.In this paper,the floating self-correction system of the sensor is designed to improve the anti-interference ability of the sensor and effectively reduce the measurement error.It also explores the influence of sensor structure on its signal-to-noise ratio,which has a certain reference value for the improvement of piezoresistive pressure sensor performance.