Impedance Characteristics Of The Uhf Band Passive Rfid Chip Test Analysis

Radio frequency identification (RFID) as a rapidly develop technology, a non-contact automatic identification technology, in theory and practical application aspects of eye-catching in recent years. An ultra-high frequency (UHF), the passive RFID technology has fast identification speed, long identified distance and service life, will be widely applied to variety of areas. Thus the research of UHF band RFID has a good prospect. The tag is consist of antenna and chip which decide the performance of electronic tags. Thus the impedance accuracy test of the chip is very impedance for designing antenna and improving RFID system performance.The passive, small and RF of the chip have difficult on impedance test. In this paper, theory and practice are combination, the test board is made, the test method is authenticated by use of the NXP_G2XM and the Impinj chip. Impedance changes with frequency, power and working condition and so on are analyzed.The paper analysis the concept and the test method of the sensitivity. The curve of the sensitivity changes with frequency are measured for the chips. This will lay the foundation for the impedance test. Three methods of the impedance test which are impedance fitting, simulation analysis and matching network testing methods are summarized. The curve of the impedance changes with frequency, power and working condition are described by impedance fitting method and Matlab. The approximate test methods of impedance are introduced by simulation analysis in the chip design progress. The impedance can be measured and the curve impedance changes with frequency in 860MHz～960MHz can be described by matching network testing method and Matlab. Finally, advantages and disadvantages of various testing methods are analyzed.