A new DC cancellation technique for a mixer-first receiver in UHF RFID reader

A new DC cancellation technique for a mixer-first receiver in UHF RFID reader is presented in this paper. A band-pass filter composed of an inductor and a capacitor is proposed to cancel the large DC component caused by the carrier leakage at the output of the passive mixer where the mixer is the input stage of the receiver to achieve a high 1dB compression point. Simulation results indicate that the attenuation to the DC component is around -50dB and the settling time is only 6μ S at the data rate of 400 kbps and shorter than that of the conventional AC coupling. The receiver is capable of demodulating the weak tag signal under a strong transmission leakage. Therefore the proposed technique can extend the dynamic range of the receiver.