Research On Key Technology For 13.56MHz RFID System

Radio frequency identification (RFID) technology is developed from the automatic identify technology. Compared with the automatic identify technology, RFID technology has many advantages, such as untouchable operation, convenient application, readable and writeable, anti-pollution et al. so it is widely used in many fields, such as industrial automation, commercial automation, identification, traffic and transport control system et al. There are many kinds of frequency used in RFID system, range from tens of thousand Hz to tens of Giga Hz. 13.56M Hz, belong to HF frequency range, is widely applied, because it has the property of un-substitute.Now, the difficulties in designing RFID system are mainly focused on untouchable tag. The untouchable label is consisted of RF interface circuit, logic control circuit and memory circuit. Among them, The RF interface circuit is the great difficulty and emphasis.The electromagnetism theory applied in RFID system is discussed deeply in this dissertation. Tag RF interface circuit in RFID system is designed based on the 13.56 Hz ISO/IEC 15693 international standard. Single phase whole wave commutation circuit and voltage-stabilizing circuit are adopted to supply tag voltage. In order to prevent the interference, two groups of voltage source are designed to supply voltage to RF interface circuit and digital control logic circuit separately. In order to accomplish the data process and conversion, the clock generation circuit,100% modulation signal and 10% signal demodulation circuit are designed. Because the design of 10% signal demodulation circuit is more difficult, the two stage push-pull amplified circuit is designed to demodulate the 10% modulate signal. Whereas the designed tag is readable and writable, E2PROM is adopted as the memory unit. In order to supply the E2PROM unit with the high programming voltage under written process, ten stage serial voltage doubler charge pump circuit is designed, compared with the general Dickson charge pump circuit, this circuit is more efficient, and can work under lower voltage. The integrity of dada transmission in RFID system is analyzed and investigated. The disadvantage of common cycling redundancy check circuit, a new cycling redundancy check circuit is proposed. The circuit not only can check the received serial data, but also can generate the transmitted cycling redundancy check code, which is provided to the receiver to check the data.Based on the Charter 0.35μm bi-poly silicon process, Hspice is utilized to simulate the RF interface circuit and the voltage doubler charge pump circuit. Verilog-XL is used to simulate the cycling redundancy check circuit. The simulation results show that RF interface circuit provides the tag with energy and time sequence. Voltage doubler charge pump circuit can generate the programming voltage over 17 V. the cycling redundancy check circuit can do the cycling redundancy check and the generation of cycling redundancy check code correctly.