The Design And Research Of Matching Detection Circuit Of SAW Gas Sensor

Surface acoustic wave(SAW) sensor is a new type of sensor, compared with the traditional sensors, it has small volume, low cost, high sensitivity, high integration ability, strong anti-jamming ability etc. In order to complete the purpose of measurement, the surface acoustic wave sensor using surface acoustic wave device for switching element, it can transform the measured parameters into output signal, the change of surface acoustic wave gas sensor by measuring device in the physical properties of the absorbed gas, such as the change of the velocity, the reference amplitude, the phase shift and so on. Based on the piezoelectric properties, the surface acoustic wave devices transmit high frequency signal, so the surface acoustic wave sensor is easy to be used for the wireless sensor. Surface acoustic wave gas sensor is composed of the adsorption sensitive thin piezoelectric substrate and the corresponding matching circuit. The matching circuit is an important part of the whole sensing system, and it acts as an important role for the SAW sensors.This article mainly study on the surface acoustic wave coal mine gas sensor matching circuit. The surface acoustic wave delay line device of coal mine gas sensor based on the dual channel oscillator is used, and the designs of band-pass filter circuit, signal mixing circuit, low pass filter circuit and adjusting circuit are all made. The theory and simulation analysis part of circuit are also made. Besides, the real surface acoustic wave gas sensor matching detection circuit is fabricated, debugged and tested.The matching circuit of surface acoustic wave coal mine gas sensor includes the band-pass filter circuit, the signal mixing circuit, the low pass filter circuit, and the amplifying and shaping circuit, and each part of circuit design both includes theory analysis and simulation, the theoretical analysis uses the Agilent’s Advanced Design System(Advanced Design System, ADS) software and the Multisim12.0 software of NI company for the circuit design. The performance index of the two circuits are analyzed, and this paper gives the simulation of AC analysis and transient simulation for voltage-controlled voltage source type and infinite gain multiple feedback type low-pass filter circuits with the Multisim12.0 software. This paper contains the amplifying and shaping circuits, and gives the analysis of the circuit. The printed circuit board(PCB) plate is designed by using the Altium Designer 6, and some work of the circuit testing and debugging is made.The design and fabrication of the surface acoustic wave detection circuit has been done in this paper, which has some reference for this kind of sensor’s application.