An Active Tag Using Carrier Recovery Circuit for EPC Gen2 Passive UHF RFID Systems

An active tag using carrier recovery circuit (CRC) is proposed in this paper. The active tag is compliant with electronic product code class-1 generation-2 (EPC Gen2) passive ultrahigh frequency (UHF) radio frequency identification (RFID) protocol, and it is used to extend the read range of EPC Gen2 RFID systems without changing existing readers. The EPC Gen2 compliant active tag is not reported yet, since it is difficult to generate a synchronized carrier with the reader in the active tag. Hence, the requirements of tag carrier are analyzed in detail, and a suitable CRC is proposed to track and hold the reader frequency in the active tag. An active tag prototype is designed to prove the proposed concept, and the communication between the prototype and a commercial EPC Gen2 reader is verified. The sensitivity of the tag prototype is -39.5 dBm and the output power is -4.5 dBm. That results in a 154.6 m read range under 36 dBm effective isotropic radiated power (EIRP) reader output power and -80 dBm reader sensitivity.