Design of a transmitter front-end for portable UHF RFID reader

A transmitter front-end circuit applied in the portable UHF RFID reader is designed and fabricated in 0.18 μm CMOS process. The designed active I/Q up-mixer can realize all three modulation schemes specified in EPC Global Class-1Gen-2 protocol by switching the input signals of Q branch. With the realization of seven-class digitally adjustable conversion gain, the driver amplifier can effectively pre-amplify the output signals of up-mixer. Measured at 1.8 V power supply, the major performance parameters of the transmitter front-end circuit are described as follows: the up-mixer achieves -14.9 dB V_rms input-referred P1 dB, 3.18 dB conversion gain and 13.20 dB NF, and the DA features 3.5 dBm output-referred P1 dB at 50 Ω, 7.90~16.30 dB conversion gain variation, and 3.10~5.00 dB NF range.