Research And Design Of Low-power RF Front-end For UHF Pasive Tag

Radio Frequency Identification (RFID) technology is a non-contact automatic identification technology which use radio frequency signal and its spatial coupling and transmission characteristics to proceed two-way communication and achieve the automatically capture of stationary or moving objects and access to relevant data. Identification, management and tracking technology to people and goods of Radio Frequency Identification can be used for anti-fake, security, public services and also can be used for Military, logistics and commercial trade. RFID have a significant impact on logistics supply chain especially. It can track the goods from the production begins and optimize the production, processing,transportation, storage and distribution. Ultra-high frequency (UHF) radio frequency identification technology has further identification distance, faster identification speed, therefore it become the main direction of development and application.Firstly, the working principle of radio frequency identification system and structure is introduced in this paper, and then elaborates working principle of UHF passive tags. UHF passive tag has further identification distance and low cost. Because there is no internal power supply, it depends on the RF energy from the reader. When the tag is far from the reader, it just can get weak energy; at this time the power consumption of tag is the main factors to restrict the function. Passive RFID tags include RF front-end circuit, digital control circuit, and electrically erasable memory. A new RF front-end circuit is proposed in this thesis. Compared with traditional RF front-end circuit, it has lower power consumption and performance is more competitive. In the specific circuit, a more efficient power generation circuit is designed with protection, the requirements of the RF signal strength is lower. Then, a low-power modulation and demodulation circuit is proposed which accord with EPC C1G2 Protocol standards for UHF passive tags. The circuit occupied a smaller area and has stronger anti-interference ability. Finally, a low-power clock circuit is presented which limits the current flow in the circuit. Simulation result shows that the circuit is suitable for UHF passive tags.