Research And Design Key Circuits Of RF Front-end In Single-Chip UHF RFID Reader

RFID (Radio Frequency Identification) is an automatic identification technology, with which data can be duplex transported contactlessly between reader and tag. Because of its many advantages such as contactless, long working distance, suitable for bad environment, efficient recognizing ability, RFID is rapidly spreading in industry, commerce, and traffic transport management fields etc. In this paper, UHF RFID reader has been carefully researched.In this dissertation, according to the protocol of UHF RFID reader, analyzed the system requirements, then presented the advantages and disadvantages of several types of the receiver's structure, Finally, the system solutions and receiver structure are proposed. In the paper, designed the RF front-end circuitry, including RF front-end circuits in receiver, and upmixer, low-noise drive amplifier in RF front-end of transmitter. This design is implemented by IBM 0.18μm RF CMOS process, layout design and post-layout simulation is then implemented.Characteristic works in the dissertation are summarized as follows:1,A zero-IF receiver of UHF RFID reader is proposed. Based on system requirements, the specification for the RF front-end circuit is presented.2,According to system requirements of receiver, designed the three-step-current RF front-end circuit, including transconductance stage, switching stage and transimpedance stage. The simulation showed the noise figure is 15dB, P1dB is 0.2dBm, and gain of 10.2 dB. Compared to traditional RF front-end circuit, the noise, linearity and gain are improved.3,According to system requirements of transmitter, design the I/Q double balance upmixer and drive amplifier. Upmixer can achieve SSB-ASK, DSB-ASK and PR-ASK modulations. Differential low noise driver amplifier in transmitter can achieve 7-class adjustable gain, and is very flexible to control the transmitted signal power. According to the system specification, in upmixer, the P1dB point is 4dBm and noise figure is 8.5dB. In low noise drive amplifier, maximum gain is 14.3dB, and noise figure is only 2.9dB, the output P1dB point is 8dBm, which meet the system requirements.