A Differential Phase Detection Circuit System for Surface Acoustic Wave Gas Sensor

Abstract

The invention discloses a surface acoustic wave differential phase detection circuit system applied to a gas sensor, comprising a surface acoustic wave gas sensing array, a differential phase detection circuit, a matching network and an A / D conversion module; the surface acoustic wave The gas sensing array is composed of a group of delay-line sensor devices deposited with gas-sensitive materials and a reference device; the phase detector circuit is composed of a signal excitation source, two signal distributors and a group of phase detectors with the same number as the sensor devices. The signal excitation source excites the electric signal with the same frequency as the sensing array, and distributes it to the sensing device and reference device in the sensing array through the signal distributor to excite the surface acoustic wave propagating along the surface of the piezoelectric crystal. The signal of the reference device is compared with the signals of each group of sensing devices through the phase detector through the signal distributor, and the output signal is converted into a digital signal by the A / D conversion module. The influence of device loss on system stability is greatly reduced through the phase detection circuit design, and the problems of high noise and long warm-up time are solved.

Description

technical field [0001] The invention relates to radio frequency circuit design technology, in particular to a surface acoustic wave differential phase detection circuit system for a gas sensor. Background technique [0002] Micro wearable gas detection and alarm technology is an important means of chemical protection in the fields of national defense, public safety prevention and control. The rapid development of individual soldier comprehensive protection system requires further miniaturization and light weight of chemical protection equipment. Compared with other existing methods, surface acoustic wave gas detection and alarm technology has the characteristics of miniature, light weight, high sensitivity, fast response and low power consumption, which has won people's favor, developed rapidly, and has been used in chemical defense and other fields Apply gradually. A typical surface acoustic wave gas sensor is composed of a surface acoustic wave gas sensor and its excitat...

AI Technical Summary

Problems solved by technology

The biggest problem facing the sensing circuit of the oscillation structure is that the loss of the surface acoustic wave sensing device directly affects the frequency stability of the oscillation circuit; in order to obtain a large loop gain, multi-stage amplification is usually used, which increases the complexity of the circuit. In order to improve the frequency stability of the system, some designs use low-frequency surface acoustic wave sensor devices. , but it also sacrifices the sensor detection sensitivity

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