Patent ID: 8823493

Claim:
A Radio Frequency Identification (RFID) reader circuit, the reader circuit comprising: a Radio Frequency (RF) source input in a transmitting path, the RF source generating a carrier wave; a RF modulator in parallel with a bypass; at least one switch for selectively coupling an output of the RF modulator to the transmitting path or an output of the bypass to the transmitting path; and a RF power amplifier in the transmitting path; a low noise amplifier in the receiving path; and a first RF bandpass filter in a signal path between the RF source input and a mixer module, wherein an output of the RF source is coupled to the RF power amplifier when the switch couples the output of the RF modulator to the transmitting path, wherein an output of the RF modulator is coupled to the RF power amplifier when the switch couples the output of the RF modulator to the transmitting path, wherein the mixer module multiplies a first signal from the first RF bandpass filter with a second signal from the receiving path to recover backscatter sidebands in the second signal.