A semiconductor wafer includes a plurality of dies. Each of the plurality of dies includes a radio frequency identification (RFID) tag circuit and a coil. The RFID tag circuit includes a tag core, an RF front-end circuit, an ID decoder, a comparator and conductive line for a unique ID. The RF front-end circuit is configured to receive electromagnetic signals through the coil in each of the plurality of dies and to convert the received electromagnetic signals into commands. The ID decoder is configured to receive the commands and to generate an expect ID. The comparator is configured to compare the unique ID with the expect ID to generate a comparison result. The comparison result is arranged to decide if the tag core is configured to receive commands.