The Key Technology Research And Circuit Optimization To The Front-end Of UHF RFID

As one of the key means to achieve the "Internet of Things", radio frequency identification technology has developed rapidly in recent years, has been widely used in daily life, production practice and many other areas. At present, the single-chip solution for the full sense to the UHF radio frequency identification system has not been introduced, and the existing UHF reader has some problems, such as complex structure, high power consumption and low isolation etc. The paper has designed the front-end of UHF RFID reader, which is based on ISO18000-6C agreement and the reference to China's "800/900MHz Band Radio Frequency Identification (RFID) technology (Trial)", and the commercial reader performance parameters of RF front-end design. The key technical and the functional circuit optimization to the reader RF front-end were studied.The main contents are as follows:The article introduces the prospect of"the Internet of things"and the basic principles of radio frequency identification firstly, and analysis simply the ISO/IEC18000-6C protocol specification as well; The RF front-end of the reader is accomplished by the direct-conversion architecture, phase-locked loop (PLL) frequency synthesizer technology and zero-IF receiver technology after comparing various transmit and receive structures, based on the requirements of ISO/IEC18000-6C protocol parameters.For the transmitter circuit, some factors that can impact the performance parameters of the transmission, such as ACPR and EVM, were analyzed, he corresponding solutions and the linear power amplifier has been studied; According to the actual need, the power detection and power control functions of the transmitter circuit have been perfected to enable the transmission power can be adjusted.In the receiving circuit, the carrier leakage suppression circuit unit was completed under the ISO/IEC18000-6C protocol requirements and the characteristics of zero-IF transceiver, the isolation value can be mproved by 30dB, then the LNA unit joined the receiving circuit to improve the program, and some performance parameters were analyzed.What the front-end require to the oscillator output was analyzed, and the oscillator circuit unit was designed by phase-locked loop (PLL) technical. The frequency hopping was spreaded after the receiver circuit is improved. What's more, the wireless interface between the reader and the processor was designed in the in the ISM band.After connecting to the base-band circuit, a test platform was built, and the comprehensive debuging and test analysis to the entire radio frequency identification system was made. What the test results demonstrated is that, the design realized the effectively identification of the RF reader to the electronic tags, and completed the reading to information carried by the tags.At the end, the problems encountered in the process of system design and debugging were summarized, some corresponding preventive measures were listed, and the paper also inducted some development and optimization direction to the RF front-end.