Biography
Enrollment Date: 2006
Graduation Date：2011
Degree：Ph.D.
Defense Date：2011.09.01
Advisors：Hongyi Chen Chun Zhang
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Research on the Key Technologies of Single-chip UHF RFID Reader
Abstract:
The ultra high frequency (UHF) Radio Frequency Identification (RFID) is an automatic identification technology using electromagnetic waves as the communication media, which has a promising market prospect. In order to cut down the application cost, the single-chip integration has become the development trend of the UHF RFID systems. However, compared with the reader using discrete components, the performances of the single-chip reader are still unsatisfactory, such as the insufficient maximum transmit power and the limited receive sensitivity. This dissertation aims at the performance improvement of the single-chip UHF RFID reader and mainly focuses on the research of increasing the transmit power and the receive sensitivity in the presence of a strong carrier leakage. First of all, several key factors which have effect on the receive sensitivity are analyzed. The sensitivity of the receiver is not only affected by the blocking effect of the carrier leakage, but also related to the phase and thermal noise leakage of the transmitter and the noise performance of the receiver itself. This dissertation further analyzes and gives the contribution of each factor to the overall receive performance so as to provide a theoretical basis for the circuits design. Based on the RF power amplifier (PA), a multi-mode low noise transmitter is proposed. This transmitter exploits the half-duplex character of the RFID reader, and fulfills the requirements of the spectrum mask and the low noise output at the same time. Furthermore, by the help of the bias noise filtering, the output noise power of the proposed PA is reduced. For RF front-end of the receiver, a polyphase network based quadrature passive mixer is presented. This mixer not only has a high linearity, but also avoids the phase noise problem induced by the local oscillator driver through the polyphase network. Moreover, the noise performance of the passive mixer in the presence of a strong input power is analyzed and optimized. To improve the noise performance of the receiver itself, an analog baseband low noise amplifier (BBLNA) with a high gain and a low noise figure is proposed. Although the BBLNA is designed as an open-loop amplifier, its performance is stable despite the variations of the process, the supply voltage and the temperature. Based on the above technologies, an UHF RFID reader transceiver chip aimed at the high-end applications is designed and implemented. The chip is fabricated in 0.18μm CMOS process. The maximum transmit power achieves 27.8dBm and the input 1dB compression point of the receiver RF front-end is 11.6dBm. Under the condition that a -1.3dBm carrier leakage is injected to the receiver, the sensitivity could still achieve -68dBm. Compared with the conventional transceiver, the proposed reader transceiver effectively improves the receive sensitivity in the presence of a strong carrier leakage.