An analog front-end for 13.56 MHz multi-standard RFID system

We analyzed 13.56 MHz RFID standards and obtained specifications of transmitting section and receiving section of the RFID reader. With these analyses, we proposed a multistandard 13.56 MHz RFID reader system. For supporting multistandard in 13.56 MHz RFID system, circuits for controlling modulation index and power emitted to the tag are added in transmitter. In order to accept to various response signal levels from the tag, a certain voltage is applied to the receiver after eliminating DC voltage at VGA input and internal reference voltage is set in comparator. From measurement using commercial tags and additional FPGA board, we can conclude that this transceiver chip is compatible with mentioned standards.