An isolator-less CMOS RF front-end for UHF mobile RFID reader

Abstract

RFID systems are based on backscattering communications, and this encourages research on how to guarantee a reliable RX performance under simultaneous TX/RX operation. To isolate RX from the TX self-jammer, the RFID transceivers are generally accompanied by an off-chip circulator or isolator. This has advantages in selectivity between tag signal and blocker, but it results in a low level of integration and bulky system. In addition, to meet the stringent linearity requirement, the RFID reader needs to adopt a linear PA with sufficient power back-off, which degrades a global efficiency. Considering that battery life time is the critical issue particularly for mobile applications, existing UHF RFID readers are unsuitable for the mobile RFID technology due to their low system efficiency and low integration level.