Biography
Enrollment Date: 2010
Graduation Date：2013
Degree：M.S.
Defense Date：2013.05.28
Advisors：Chun Zhang
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Key technology and Application Research of Passive RFID Tag
Abstract:
With the great progress and development of RFID technology of recent years, the Internet of Things industry has achieved amazing expansion. Among them, the most fastest growth application is the passive UHF RFID technology. Thanks to the great advantage of the passive UHF tag such as long reading distance, fast reading speed and low cost, the passive UHF tag achieved widely applications in transportation, storage, medicine, security et al. This article is mainly focus on the low power circuits design, antenna design and sensor application of the passive RFID tag.The research of the passive RFID tag is organized as three parts: basic tag circuits, antenna technology and temperature sensor tag. On the development of the low power tag circuits design, the focal points are the analysis of the tag’s front-end impedance and the design methods of power rectify circuit. Also, on the basic of the research, we design a RRAM memory tag chip compatible with 18000-6C. This chip is implemented in standard 0.18um technology of HHNEC. The test results show that the tag chip successfully achieves the normal communication function.On the study of the tag antenna technology, this article is mainly about the On-chip Antenna (OCA) and inductively coupled antenna technology. OCA could greatly minimize the size and cost of a complete tag and the inductively coupled antenna could expand the working distance of the OCA tag. With the previous research of our group, we implemented a custom protocol OCA chip in UMC 0.18um technology. With all the tag modules include OCA, analog circuits, digital circuit and OTP, the whole chip size is only 600x600um2. The test results show the tag achieves above 2mm reading distance with 20dBm reader power (the reader antenna is poorly matched). The research of the inductively coupled antenna is mainly focus on the design of ultra small inductively coupled antenna. This article realizes a paper substrate inductively coupled antenna with only 1x1.1cm2 size. The test result shows the inductively coupled antenna with OCA tag gets above ten times of the orginal reading distance of only OCA tag.On the design of the temperature sensor tag, this article uses the BJT structure plus SAR ADC structure to achieve low power temperature sensor. And the accuracy of ±0.5°C is achieved during the simulation with temperature range from -40°C to 85°C. The temperature sensor tag is manufactured in UMC 0.18um technology with 1x1.5um2 chip size. The test result shows that the whole tag chip has a sensitivity as low as -9.7dBm. Also, the temperature sensitive voltage generated module of BJT structure is working with great linearity under the restricted test environment. With high resolution thermometer, this module can chieve better test result.