A High Efficiency Rectifier for UHF RFID Passive Tags with vth Cancellation Technique

In this paper a high sensitivity and high power efficiency full wave rectifier is proposed for UHF RFID applications at 953MHz frequency. The cross-coupled structure is used in the design; also the bootstrap circuit is employed to eliminate the effect of threshold voltage of pass transistors. For the purpose of improving the power efficiency and the chip area, the sizes of transistors are adjusted in UHF frequency. In this rectifier the power efficiency changes from 62.7% to 76.1% and the voltage conversion ratio changes from 62.8% to 77.3% for the variation of input voltage from 0.7V to 1.8V. The simulation of the proposed rectifier is done in 0.18µm CMOS technology with the help of Cadence software, while the chip area is 0.00525mm2.)

Keywords:

RFID , Ultra-high frequency (UHF) , rectifier , Vth cancellation