In order to increase the robustness of a RFID digital circuit against SEUs, fault injection is commonly used to locate weak areas. In circuit-emulation is a very powerful tool to locate these areas by executing huge fault injection campaigns. In this work, fault injection has been extensively applied to the digital baseband of an UHF RFID tag during the communication with a RFID reader. A large number of fault campaigns have been performed in order to identify the most sensitive parts in the digital baseband. Following this analysis, a first low cost countermeasure is introduced and validated