RFID reader front end

An RFID reader analog front end architecture employs multiplexed use of a single analog to digital converter in order to digitize the inphase and quadrature components of the incoming signal from the reader's receiving antenna. The Type 1 architecture includes an analog I/Q switch that controls which of the baseband signals will be digitized by a single Analog to Digital Converter. In the Type 2 architecture, the I/Q switch is moved so that it is directly adjacent to the receive mixers, requiring only one antialiasing filter block and gain block. In the Type 3 architecture, one mixer and its associated filtering chain are eliminated. The Type 4 architecture provides for selection of transmitter phase basis by means of an I/Q switch operating under control of the DSP that phase-shifts the transmitter with respect to the receiver.