Research On Resonant Pressure Sensor Testing System Based On Linear Feedback Control

MEMS(Micro-electro-mechanical system)resonators are widely used in industrial production,aerospace and other important fields due to their small size,high precision,good stability,and they have received extensive attention from scientific research institutions in various countries.However,it is difficult to directly test the output signal of the resonator,because the output signal of the resonant pressure sensor is weak and susceptible to the external environment and its own inherent characteristics.Therefore,choosing a suitable detection method can not only improve the accuracy of the resonant pressure sensor,but also have important significance for improving the stability and reliability of the test system.In this paper,AGC automatic gain control system and phase-locked loop control system are used to test the resonance frequency of the resonant pressure sensor.However,both test systems have their own defects and limitations.In order to overcome system defects and improve system performance,this paper designed a closed-loop resonant pressure sensor detection system based on linear feedback to complete the resonant pressure sensor.Test analysis,and improve the test system's test accuracy and quality factor of the vibrating pressure sensor.The main research work and achievements of this paper are as follows:(1)The working principle and closed-loop detection principle of resonant pressure sensor based on three-layer silicon-silicon bonding structure were analyzed.Several different closed-loop system excitation and detection methods were discussed.The advantages of several different drive detection methods were analyzed and compared.(2)The principle of self-excited control of resonant pressure sensor is analyzed.The closed-loop simulation model and test circuit based on AGC automatic gain control system and phase-locked loop control system are established.The self-excited oscillation of the resonant pressure sensor is realized,and the resonant frequency of the resonant pressure sensor is tested.In addition,the loop stability of the phase-locked loop system is analyzed and a method for improving loop performance is obtained.(3)Establish a nonlinear model of a resonant pressure sensor and a closed-loop simulation model based on a linear feedback system.Build a test circuit to measure the amplitude-frequency characteristics of the resonator.Analyze the simulation and test results and find that using a closed-loop test system based on linear feedback improves the resonance peak of the resonator by 6.5 dB.At the same time,the accuracy of the system and the quality factor of the resonator have been greatly improved.The influence of the steady-state phase error of the system when the input signal changes is analyzed.