Importance

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Abstract

A system for increasing the sensitivity of a receiver in an RFID tag reader. The system includes a directional coupler which receives the signal transmitted by the reader and which receives a backscatter signal from the RFID tag. The output of the directional coupler includes a transmit reference signal and a combined signal comprising the received signal and a transmit leakage signal. A first feedback loop generates an amplitude-compensated reference signal including a transmit signal component having the same amplitude as the transmit leakage signal. A second feedback loop adjusts the phase angle of the amplitude-compensated reference signal to a phase angle 180 degrees out-of-phase with the combined signal, to generate a canceling signal which effectively cancels out the transmit leakage signal component of the combined signal thereby improving the signal-to-noise ratio thereof.

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First Claim