Investigation Of Energy Conversion Technologies For Passive RFID Tag IC

Radio Frequency Identification (RFID) is a kind of Technology which can automatically identify objects and get their information. RFID system is composed of two parts, one is reader (it is also called interrogator or signal transmitter), the other is tag (it is also called transponder or signal acceptor). The energy conversion is one of the most important parts in passive RFID tag. It is the interface between the RFID tag chip and the outside, and it converts the magnetic field energy in the antenna to the electrical energy for tag chip. Meanwhile, it implemented the conversation of AC to DC.Firstly, this paper systematically studied two energy conversion methods of RFID tag. One is inductance coupling, and the other is electromagnetic coupling. The importance of resonance circuit and the impedance matching circuit has been analyzed. Additional effect factors on quality factor and power transmission coefficient are analyzed deeply.Secondly, on the basis of this two energy generation methods, rectifiers of the HF and the UHF RFID tag are studied. Their theory models are built, studied and analyzed deeply. The paper also studied the output voltage and the energy conversation efficiency. The rectifier circuit of the HF RFID tag based upon the ISO15693 protocol and the pump multi-voltage rectifier circuit of UHF RFID tag based upon the ISO18000-6C protocol are designed. After comparing the simulation result and the theory analysis result of the circuits, it can be concluded that the theory models are correct.At last, taking the HF RFID tag for example, the paper studied the back-end of the energy conversion, and supplied the feasible advices about the layout design aiming at the influence of noise, device matching and process. The test results of the chip are presented.