Patent ID: 8081061

Claim:
A mobile radio-frequency identification (RFID) reader, comprising: a high-frequency front-end unit including an antenna, a circulator, and an output amplifier; and a signal processor chip, comprising: a high-frequency transceiver; a pseudo-leakage signal generator configured to generate a pseudo-leakage signal based on a transmission high-frequency signal, the pseudo-leakage signal corresponding to a transmission leakage signal included in a received high-frequency signal, the transmission high-frequency signal being provided from the high-frequency transceiver and being provided to the high-frequency front-end unit; and a subtractor configured to subtract the pseudo-leakage signal from the received high-frequency signal to generate a subtracted signal, the received high-frequency signal being provided from the high-frequency front-end unit, and the subtracted signal being provided to the high-frequency transceiver, wherein the subtractor comprises: an input circuit unit coupled between a first input terminal to which the received high-frequency signal is applied and a second input terminal to which the pseudo-leakage signal is applied, the input circuit unit being configured to generate a first current signal and a second current signal, such that magnitudes of the first current signal and the second current signal complementarily vary in response to a difference signal between the received high-frequency signal and the pseudo-leakage signal that are inputted to the first and second input terminals, respectively; an output circuit unit configured to generate an output voltage in response to a difference between the first current signal and the second current signal; and a bias circuit unit configured to provide a bias current to the input circuit unit.