Research And Design Of The Interface Circuit Of RFID Tag

The RFID (Radio Frequency Identification) is one of the most common technologyof auto-identification. It has the advantages of non-contact, easy operation, rapidread/write speed and high security, and it is widely used in many fields. The RFID hasenormous market value, but our RFID technology falls behind, the research and designof the RFID tag is valueable.The RF interface circuit studied in this thesis studies is the bridge of digital part ofthe RFID chip communication with the external environment. The design of the RFinterface circuit of high reliability and performance is a prerequisite whether RFID chipwork normally or not.The thesis designs an RF interface circuit. It is optimized from multi-levels ofstandard, principle, logic structure, circuit parameters and physical layout, and gainshigh performance using 0.35μm EEPROM technology. At the same time we creat asimulation model of the antenna interface, which plays an important role in thesimulation of the RF interface circuit. By comprehensive simulation, we find that theRF interface circuit complies completely with the ISO/IEC 15693 standards and hashigh performance and reliability.The research results of the thesis are as follows:1) Researches on the relevant part of the ISO/IEC 15693 RFID standard to RFinterface carefully, and analyzes energy transmit and signal interface of the RFinterface circuit.2) Establishes an antenna simulation model of remote RFID system byresearching on equivalent circuit of RF antenna interface, and analyzes thecurrent on reader antenna. The model has accurate, high-efficient advantages,just as revealed at subsequent verification on RF interface circuits.3) According to the function of RF interface, we divide the RFID interface circuitinto five parts: antenna interface, energy generation module, data modulationand demodulation, clock restoration and reset module, and interface of analogand digital part. Then design of each module is optimized to ensure highperformance and reliability.4) The preliminary generation circuit of analog power source designed has ashortcoming of high power consumption; we add a diode in the voltagenegative feedback to limit the flows. The simulation result proves that it candecrease power consumption of the circuit effectively.5) Due to the importance of RF interface to the full chip, we should consider allkinds of the factors in layout, such as floorplanning, area, noise andsymmetrical. First, each module of RF interface is allocated in the layout, and then carry on the module layout, the whole layout is optimized in the last. Inthe thesis, we present capacitance of three layers as the energy storagecomponent, and enhance the utilization ratio of the chip area greatly.6) Because of characteristics of the RF interface circuit, the variation of thetechnology and temperature should be considered. The result of simulationproves that the RF interface designed has higher resisting PT characteristic.