New Analysis and Design of a RF Rectifier for RFID and Implantable Devices

Dong-Sheng Liu,Feng-Bo Li,Xue-Cheng Zou,Xiong-Fei Tao,Yao Liu,Xue-Mei Hui

doi:10.3390/s110706494

Dong-Sheng Liu, Feng-Bo Li + Show 4 more

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https://doi.org/10.3390/s110706494

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Abstract

New design and optimization of charge pump rectifiers using diode-connected MOS transistors is presented in this paper. An analysis of the output voltage and Power Conversion Efficiency (PCE) is given to guide and evaluate the new design. A novel diode-connected MOS transistor for UHF rectifiers is presented and optimized, and a high efficiency N-stage charge pump rectifier based on this new diode-connected MOS transistor is designed and fabricated in a SMIC 0.18-μm 2P3M CMOS embedded EEPROM process. The new diode achieves 315 mV turn-on voltage and 415 nA reverse saturation leakage current. Compared with the traditional rectifier, the one based on the proposed diode-connected MOS has higher PCE, higher output voltage and smaller ripple coefficient. When the RF input is a 900-MHz sinusoid signal with the power ranging from −15 dBm to −4 dBm, PCEs of the charge pump rectifier with only 3-stage are more than 30%, and the maximum output voltage is 5.5 V, and its ripple coefficients are less than 1%. Therefore, the rectifier is especially suitableto passive UHF RFID tag IC and implantable devices.

Highlights

The rapidly increasing range of applications of radio frequency identification (RFID) technology includes supply chain management, access control to buildings, public transportation, airport baggage handling, and express parcel logistics [1,2,3]
When replacing a diode with a diode-connected MOS transistor, we have to assure that the new structure will turn on when it is forward-biased and will cut off when it is reverse-biased, so should the NMOS substrate connect to the lowest voltage, and the PMOS substrate should connect to the highest voltage
When the RFID tag enters an electromagnetic field, the input voltage is in negative half-cycle, current charges C2, C4 and

Summary

Introduction

The rapidly increasing range of applications of radio frequency identification (RFID) technology includes supply chain management, access control to buildings, public transportation, airport baggage handling, and express parcel logistics [1,2,3]. The need for lower cost, higher data rates, and longer communication distances is increasing, while severe regulation of transmission power and bandwidth have to be met. RFID tags (or transponders) are often classified as passive or active. Passive tags are powered by an electromagnetic wave transmitted by the reader, while the active tag is powered by a battery. Passive tags have the advantages of low cost and long life. As the passive tag is remotely powered by a reader’s RF signal, it must be able to operate at very low power levels (~μW) [1,3]

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