Self-Vth-Cancellation High-Efficiency CMOS Rectifier Circuit for UHF RFIDs

Koji KOTANI  Takashi ITO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E92-C   No.1   pp.153-160
Publication Date: 2009/01/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E92.C.153
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
Keyword: 
radio frequency identification (RFID),  ultra-high frequency (UHF),  rectifier,  self-Vth-cancellation,  power conversion efficiency (PCE),  

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Summary: 
A high-efficiency CMOS rectifier circuit for UHF RFID applications was developed. The rectifier utilizes a self-Vth-cancellation (SVC) scheme in which the threshold voltage of MOSFETs is cancelled by applying gate bias voltage generated from the output voltage of the rectifier itself. A very simple circuit configuration and zero power dissipation characteristics in biasing enable excellent power conversion efficiency (PCE), especially under small RF input power conditions. At higher RF input power conditions, the PCE of the rectifier automatically decreases. This is the built-in self-power-regulation function. The proposed SVC CMOS rectifier was fabricated with a 0.35-µm CMOS process and the measured performance was compared with those of conventional nMOS, pMOS, and CMOS rectifiers and other types of Vth cancellation rectifiers as well. The SVC CMOS rectifier achieves 32% of PCE at the -10 dBm RF input power condition. This PCE is larger than rectifiers reported to date under this condition.