Patent ID: 8766775

Claim:
A Radio Frequency Identification (RFID) reader circuit, the reader circuit comprising: a Radio Frequency (RF) source; a RF power amplifier coupled to an output of the RF source in a transmitting path; a first RF bandpass filter coupled between the output of the RF source and a mixer module; and a low noise amplifier in a receiving path being coupled to an input of a second RF bandpass filter; wherein the mixer module receives a signal from the first RF bandpass filter and a signal from the second RF bandpass filter, wherein the mixer module multiplies the signal from the first RF bandpass filter with the signal from the second RF bandpass filter to recover backscatter sidebands, wherein the first and second RF bandpass filters provide identical or nearly identical delay of signals feeding into the mixer module, wherein the first RF bandpass filter has an input connected to an input of the RF power amplifier and an output connected to an input of the mixer.