Signal Readout System Of Lc Resonant Sensor Based On Phase Difference Detection

At present the sensor technology has more and more applications in people’s lives withthe rapid development of technology. It is increasingly important that the sensors signal test inthe special environment important in modern life. The application capabilities of traditionalwired sensor were greatly reduced in the pressure tests at high temperatures environment andbiomedical and others aspects. For this case, the resonant LC passive wireless sensors wereproposed to solve this problem, and there are many researchers that invest a lot of energy athome and abroad. In this paper, the theory of the sensor signal readout was studied, at last wechosen the method of sensors signal readout system based on phase difference detectionwhich was got proved by the experiment.The energy transfer process and the signal readout theory are analyzed between passiveLC the sensor and the signal read coils in this paper. According to the characteristics of thephase change in the impedance of the read coil, The method of phase difference acquisition isstudied based on the direct and indirect mixing mode, as well as to improve the accuracy ofthe sensor signal test and the input signal mode of the readout coil is improved. According tothe variation characteristics of the phase difference signal, a block diagram of the overalldesign of the passive LC sensor signal readout system is designed, which includes the moduleof accurate linear sweep source, the detection of phase difference, digital-analog conversion,and a USB communication module, etc., and the kind of circuit board production is complete.The register configuration and corresponding program is completed on the high-precisionlinear sweep baed on the mode of ROM and digital ramp DRG. At the same time the relevantprocedures by the master chip of data acquisition and USB-FIFO communication mode anddata upload are completed, and ultimately read function of the sensor signal is achieved.During the test, the precision linear sweep source based on the mode of ROM andDRG model is corresponding tested firstly，and then the results was compared. The experiments show that the precision linear sweep mode source DRG-based has advantage ofhigh accuracy and sweep quick. The different phases of the input signal and the output voltageof the module is a linear relationship in the phase detector module performance testing. Thetest platform is established, and the signal readout system can readout the signal of passiveLC sensor with the changing pressure in a pressure experiment.