A fully integrated passive and battery powered semi-active UHF RFID transponder chip supporting EPC Gen 2 protocol is presented. The proposed transponder works as a passive RFID tag when the generated RF-power is sufficient to operate, otherwise it operates in semi-active mode using battery power. The chip has re-writeable non-volatile memory bank formed by FeRAM and on-chip temperature sensor. The memory consists of EPC memory bank for EPC functionality and temperature bank for storing sensed data. The standby current in semi-active is about 0.5uA, the lifetime in semi-active mode is in excess of 2 year with a 10mA-hr thin film battery.