Design and Experiments of a Novel Low-Ripple Cockcroft-Walton AC-to-DC Converter for a Coil-Coupled Passive RFID Tag

Toshitaka YAMAKAWA  Takahiro INOUE  Akio TSUNEDA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E91-A   No.2   pp.513-520
Publication Date: 2008/02/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e91-a.2.513
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
RFID,  wireless power feeding,  AC-DC converter,  diode charge pump,  

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A low-ripple diode charge-pump type AC-DC converter based on the Cockcroft-Walton diode multiplier is proposed for coil-coupled passive IC tags in this paper. This circuit is developed as a power supply for passive RFID tags with smart functions such as heart rate detection and/or body temperature measurement. The proposed circuit converts wirelessly induced power to a low-ripple DC voltage suitable for a 13.56 MHz RFID tag. The proposed circuit topology and the principle of operation are explained and treated theoretically by using quasi-equivalent small-signal models. The proposed circuit was implemented on a PCB. And it was confirmed that the proposed circuit provides 3.3 V DC with a ripple of less than 20 mV when a 4 Vp-p sinusoidal input is applied. Under this condition, the maximum output power is about 310 µW. The measured results were in good agreement with theoretical and HSPICE simulation results.