Efficiency Improvement in Photovoltaic-Assisted CMOS Rectifier with Symmetric and Voltage-Boost PV-Cells

Koji KOTANI  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E98-A   No.2   pp.500-507
Publication Date: 2015/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E98.A.500
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
Category: 
Keyword: 
energy harvesting,  rectifier,  photovoltaic cell,  

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Summary: 
Efficiency of the photovoltaic-assisted UHF CMOS rectifier, which is one example realization of the synergistic ambient energy harvesting concept, has been improved by symmetric PV cell structure. Balanced biasing for the n-channel and p-channel diode-connected MOSFETs realized by the symmetric PV cells effectively compensates Vths and prevents useless leakage current, resulting in the improved efficiency of the rectifier under low input power conditions. In addition, by extending the balanced biasing concept, output-voltage-boosted PV cell structure was proposed and found to be effective for further improving the efficiency of the rectifier. As a result, under a typical indoor lighting condition of 300lx, power conversion efficiency of 25.4% was achieved at -20dBm of 920MHz RF input and 47kΩ output loading conditions, being 3.6 times larger than a conventional rectifier without PV assistance.