The Design of a Low-cost Impedance Matching Network for Passive UHF RFID Tag

A low-cost impedance matching network for compliant ISO/IEC 18000-6C passive UHF RFID tag is presented.Based on complex power wave reflection coefficient,the on-chip matching network is designed through modifying the chip input impedance which varies between conjugate match and mismatch with the tag antenna to modulate the backscattered signals effectively.This matching network with simple structure can maximize the power transfer between the reader,antenna and chip,increase the input supply voltage and improve the identifiability of the backscattered signals.The tag chip with this impedance matching network has been fabricated with chartered 0.35 μm CMOS process.Operated in the 923 MHz band,experimental measurement shows that the output of the voltage multiplier is up to 1.47 V,and the tag meets the specification of the system.