Biography
Enrollment Date: 2006
Graduation Date：2009
Degree：M.S.
Defense Date：2009.06.02
Advisors：Yongming Li
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Research of Key Technology in Analog Front-end Circuit of RFID Transponder
Abstract:
Radio Frequency Identification (RFID) is a kind of contactless automatic identification technologies which identify individual items and exchanges data between a reader and a transponder (RFID tag) based on transimission characteristic of electromagnetic coupling or radar reflecting. Because of the merits of informative storage, easy to reading and writing, anti-interference ability, intelligence, strong confidentiality, etc., the RFID technology can be applied to logistics management, traffic control, electronic ticketing and many other fields. Compare to the LF or HF RFID tags, farther working distance, higher data transmission speed, smaller chip size and low cost make UHF (Ultra High Frequency) passive RFID tags a good market prospect to research.
Application of RFID technology is restricted by the transmitting power of reader, BER (bit error rate) of system, energy conversion efficiency of tag (include antenna and chip), power dissipation, chip cost, etc. This paper has two main works, which is based on 0.18-μm CMOS technology. First, this paper presents the design and test results of two passive RFID tag’s analog front-end circuit chips, whose frequency is 915MHz, based on ISO18000-6 Type C protocol. Both of the low-voltage low-power chips are optimized by improving the stability and anti-noise performance of demodulator and reducing the power dissipation of oscillator caused by parasitic effects. Then, a self-adaptive low-voltage current-mode amplitude shift-keying (ASK) demodulator design is proposed, which adopts current-mode techniques. Test results show that it could operate under the supply voltage range from 0.6V to 1.8V, the input carrier magnitude range from 250mV to 1.1V, and the modulation depth range from 10% to 100%. Under the voltage supply of 0.6V, its total current dissipation is less than 1μA.