Study of Front End of CMOS RFID Tag with Inductively-coupled Broadband Antenna

Abstract

Radio frequency identification (RFID) has received much attention. The ac to dc conversion efficiency is crucial for long range application in UHF band. The front end of the passive tag combined with the broadband antenna at 915MHz is investigated. Two subjects of high efficient charge-pump and antenna matching are focused. The chip is fabricated by TSMC 0.18um 1P6M CMOS. The antenna is on the 0.4mm FR4 pc board. With ten stages of capacitor-diode pair, the multiplier factor is 8.575 and dc voltage can reach to 3.4V and is regulated to 850mV with input power lies between 6 similar to 8dBm. Under matching, the communication range can reach to 4m.