Patent ID: 8410905

Claim:
A radio frequency identification (RFID) reader for cancelling a single antenna return loss and a leakage signal of the RFID reader, comprising: a digital unit configured to calculate and store an amplitude and a phase of the single antenna return loss and the leakage signal based upon baseband signals received by the digital unit during an initial non-tag operation; a leakage cancellation circuit configured to generate a single antenna return loss and leakage cancellation signal to cancel the single antenna return loss and leakage signal in response to a control of the digital unit, a first directional coupler configured to transmit to a single antenna transmit signal from a transmitter coupled to the digital unit; and a second directional coupler configured to receive the single antenna return loss and leakage cancellation signal from the leakage cancellation circuit and to cancel the single antenna return loss and leakage signal from the first directional coupler, wherein the leakage cancellation circuit is between the first directional coupler and the second directional coupler, and wherein the digital unit is configured to control the leakage cancellation circuit using the stored amplitude and phase without using an error signal fed back to the leakage cancellation circuit based upon a sensed downconverted tag signal, a sensed downconverted tag signal from a downconverter/demodulator, or a feedback signal from a detector comprising a Schottky diode, low-pass filter and a buffer amplifier coupled to the second directional coupler wherein the feedback signal is received either during a tag operation or an initial non-tag operation.