This paper presents a rectifier for passive UHF RFID tags with high power conversion efficiency (PCE) over a wide incident power range under the influence of mismatch between tag antenna and chip, which benefits read and write sensitivities simultaneously. Fabricated with 0.13 μm CMOS technology, the RF frontend adopting this rectifier achieves PCE higher than 25% with incident power from −19.2 dBm to −7.6 dBm.