Patent ID: 8120464

Claim:
A radio frequency identification (RFID) reader comprising: a transmitting circuit which generates a transmitted signal to operate an RFID tag; a receiving circuit which receives a received signal including a tag signal from the RFID tag and a transmission carrier leakage signal leaking from the transmitting circuit; and a leakage removing circuit which senses a phase and an amplitude of the transmission carrier leakage signal inputted to the receiving circuit, converts the transmitted signal from the transmitting circuit into a signal having a phase opposite to that of the transmission carrier leakage signal and an amplitude equal to that of the transmission carrier leakage signal and generates an offset signal, and synthesizes the offset signal and the received signal inputted to the receiving circuit, wherein the receiving circuit comprises a signal detector installed on the receiving circuit which detects the transmission carrier leakage signal inputted to the receiving circuit and the offset signal output from the leakage removing circuit, and wherein the signal detector detects the amplitude and the phase of the transmission carrier leakage signal inputted from the transmitting circuit to the receiving circuit.