A Fully Integrated 900-MHz Passive RFID Transponder Front End With Novel Zero-Threshold RF-DC Rectifier

• Published in: IEEE transactions on industrial electronics (1982) 2009-07, Vol.56 (7), p.2317-2325
• Main Authors: Yuan Yao, Jie Wu, Yin Shi, Dai, F.F.
• Format: Article
• Language: English
• Subjects: Backscatter modulation; charge pump; CMOS technology; low power; low voltage; Passive RFID tags; Pulse width modulation; pulsewidth modulation (PWM); Radio frequency; radio-frequency identification (RFID); Radiofrequency identification; rectifier; Rectifiers; RF-dc; Schottky diodes; Semiconductor device measurement; Transponders; Voltage; zero-threshold
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2008.2010180

This paper presents a fully integrated CMOS analog front end for a passive 900-MHz radio-frequency identification (RFID) transponder. The power supply in this front end is generated from the received RF electromagnetic energy by using an RF-dc voltage rectifier. In order to improve the compatibility with standard CMOS technology, Schottky diodes in conventional RF-dc rectifiers are replaced by diode-connected MOS transistors with zero threshold. Meanwhile, theoretical analyses for the proposed rectifier are provided and verified by both simulation and measurement results. The design considerations of the pulsewidth-modulation (PWM) demodulator and the backscatter modulator in the front end are also discussed for low-power applications. The proposed front end is implemented in a 0.35-mum 2P4M CMOS technology. The whole chip occupies a die area of 490 times 780 mum 2 and consumes only 2.1 muW in reading mode under a self-generated 1.5-V supply voltage. The measurement results show that the proposed rectifier can properly operate with a -14.7-dBm input RF power at a power conversion efficiency of 13.0%. In the proposed RFID applications, this sensitivity corresponds to 10.88-m communication distance at 4-W equivalent isotropically radiated power from a reader base station.