Patent ID: 7492812

Claim:
An RFID transceiver device comprising: a local oscillation circuit that generates a local oscillation signal; a demodulation circuit that demodulates a reception signal using the frequency of the local oscillation signal output from said local oscillation circuit; a transmission circuit that modulates, amplifies and transmits a local oscillation signal output from said local oscillation circuit; a duplexer that supplies to a transceiving antenna the transmission signal from said transmission circuit and branches the reception signal received by said transceiving antenna to said demodulation circuit; and a delay circuit between said local oscillation circuit and said demodulation circuit, wherein the amount of delay of said delay circuit is set to a magnitude corresponding to the path difference between the path of the leakage, via said duplexer into said demodulation circuit, of the transmission signal that is output from said local oscillation circuit for transmission, and the path of direct input of the local oscillation signal from said local oscillation circuit to said demodulation circuit.