A mobile terminal circuit for transmitting radio frequency identification (RFID) data to an RFID reader. The mobile terminal circuit comprises an antenna for communication with the RFID reader; a memory portion for storing RFID data together with mobile terminal protocol data; a codec for encoding the RFID data into RFID codec data; a modulator connected to the codec, for modulating the RFID codec data into RFID modulation data; a processor connected to the memory portion, for extracting RFID data stored in the memory portion and delivering the extracted RFID data to the codec; a detector connected to the antenna and the processor, for informing the processor of approach of the RFID reader; a first clock generator connected to the processor and the memory portion, for providing operation timing to the processor and the memory portion; and a second clock generator connected to the first clock generator, the codec and the modulator, for providing operation timing to the codec and the modulator.