A transponder IC for wireless auto identification system

A batteryless, self-powered transponder used in the wireless auto identification system is proposed in this paper. The paper works in a frequency of 915MHz. The transponder extracts energy from the RF field from the RFID station, and stores it for the following working phases. The transponder works in three phases. First, the transponder decodes the data bit from the RFID station. Most of the digital part does not work during this phase. Second, the transponder process the data received in the pre-phase and executes proper operation to some corresponding register or memory unit. And at last, the transponder sends a data bit back to the RFID station by optionally reflecting some wave, which can be achieved by modulating the load of the transponder. The system can be divided into three blocks: analog part, digital part and memory part.