Research And Design Of Mixer For The Front-ends Of UHF RFID Reader

The research and development on UHF RFID reader and tag are driven by the requirements in application of UHF RFID systems in recent years. Simultaneously, CMOS RFIC developed very fast and it is possible to integrate a wireless transceiver into a chip via CMOS process. Mixer, one of the most important blocks in the front-end in UHF RFID reader, is designed with large technical challenges.Design and implementation of mixer in UHF RFID reader receiver is presented in this dissertation. The difficult of the design is introduced under the UHF RFID standard. The advantages and disadvantages of several types of the receiver's structure are presented and the system solutions and receiver structure are then proposed. Based on the systematical study of the noise and nonlinearity performance, the mixers are optimized according to the demands of zero-IF receiver. A new structure of mixer is proposed witch is different from the active and passive mixer. This design is implemented by TSMC 0.25UM MIXED SIGNAL process, and the pre-simulation 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 mixer circuit is presented.2,The noise of current mixer is investigated. A dynamic noise cancellation technology is proposed to reduce the noise.3,The nonlinear behavior of current mixer is investigated. Several optimization methods are proposed to improve the nonlinear of the circuit.4,The design of a three-step-current mixer including transconductance stage, switching stage and transimpedance stage is implemented. The simulation showed that the 1 / f noise corner frequency of 90 kHz, input third-order cross-point of 14 dBm and gain of 20 dB. Compared to traditional mixer, the noise, linearity and gain is improved.