RFID Reader

摘要

Embodiments of the invention relate to the field of RFID (radio frequency identification). Some particularly preferred embodiments relate to a high-Q, "full duplex" (FDX) RFID Reader. We describe an RFID reader for reading a transponder, the RFID reader comprising: an antenna; a resonant circuit coupled to the antenna, such that load modulation by the transponder gives rise to modulation of the amplitude of an antenna voltage; means for applying negative feedback to the resonant circuit coupled to the antenna to reduce a variation in the amplitude of the antenna voltage resulting from the load modulation; and means for monitoring the load modulation to read the transponder. In preferred embodiments the means for monitoring the load modulation comprises means for monitoring a residual variation in the amplitude of the antenna voltage allowed by the negative feedback.