Design And Research Of Signal Detection Circuit For SAW Sensor

Saw sensor detection is mainly based on the change of phase, frequency and amplitude of measurement to measure to the environment changes. In this paper, we design the saw sensor signal detection circuit of detecting frequency changes.In this paper,we have designed and researched the surface acoustic wave sensor signal detection system,and the detection system is used for on-site detection of chemical and biological warfare agents for solving the problem of fast and accurate detection of biochemical warfare.The results will provide an effective way to fight against terrorism in the world.1.We have analyzed and researched the working principle and the principle of SAW sensor transmitter circuit.2.To center frequency of 250MHz SAW sensor as the research object,we used dual-channel structure that detection channels are coated film and reference channels are not coated film,and we designed the signal processing circuit including the oscillation circuit,mix circuit,shaping circuit and filter circuit.3.In view of the signal processing circuit we designed the corresponding frequency counting circuit, using for signal detection of frequency meter to determine the types of gas.4.We designed the SAW sensor temperature control circuit,using for the temperature stability of the SAW sensor,in order to achieve a higher degree of stability.For the center frequency of 250M of saw sensor, we designed three-way mixing structure to detect the three gases, and respectively, three different saw sensors coated film as a three-way detection channels separately and mixed with not coating saw sensor, and the resulting difference signal is filtered,and using PID algorithm to control the temperature in order to improve the stability of the circuitAfter frequency counting circuit, we achieve the function of the signal frequency measurement. And the results are sent to the LCD display module. And the system has been successfully developed, delivered production.