An Ultra Low Power and Variation Tolerant GEN2 RFID Tag Front-End with Novel Clock-Free Decoder

Sung-Jin KIM  Minchang CHO  SeongHwan CHO  

IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.6   pp.785-795
Publication Date: 2010/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.785
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
EPCglobal,  Class 1,  Generation 2,  RFID,  RFID tag,  pulse interval encoded,  passive,  low power,  PIE decoder,  calibration,  

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In this paper, an ultra low power analog front-end for EPCglobal Class 1 Generation 2 RFID tag is presented. The proposed RFID tag removes the need for high frequency clock and counters used in conventional tags, which are the most power hungry blocks. The proposed clock-free decoder employs an analog integrator with an adaptive current source that provides a uniform decoding margin regardless of the data rate and a link frequency extractor based on a relaxation oscillator that generates frequency used for backscattering. A dual supply voltage scheme is also employed to increase the power efficiency of the tag. In order to improve the tolerance of the proposed circuit to environmental variations, a self-calibration circuit is proposed. The proposed RFID analog front-end circuit is designed and simulated in 0.25 µm CMOS, which shows that the power consumption is reduced by an order magnitude compared to the conventional RFID tags, without losing immunity to environmental variations.