《7.RFID Tag design》.pdf

RFID Tag design This chapter takes advantage of the previous one to de- fine the specifications at the system level of an RFID tag . The operational principle as well as the comnnunicatlon protocol chosen in the hereafter developed system are presented. The different building blocks and their design issues in light of low power consumption are described . Fi- nally, the chapter concludes with the antenna choice and the experimental results [5]. 7.1 UHF and //wave RFID circuit state-of-the-art HE vast majority of todays available RFID tag ICs operate in the UHF band, Ti.e. 900 MHz. Table 7. 1 lists examples of RFID tags from different industrials. All these products share similar forward and backward link communication techniques. This is a consequence of todays standards (see section 4.5). In terms of reading range, the ST XRAOO product leads the race with 10 m or 27 //W of necessary available power from the antenna. Atmel ATA5590 is not far behind, which is not surprising since both input impedances are very similar and the two circuits operate at the same voltage. It has to be mentioned that the Zuma design from Impinj achieves 8 m of read and write distance. According to [39], these performance are made possible using the Self-Adaptive Silicon (SAS) approach. In the 2.45 GHz band, three products are industrially available (see Table 7.2) and one research work from Atmel shows a practical realization [33]. Both the EM4222 from EM and Philips Ucode are dual frequency systems. As can be seen in the Hi- tachi II chip, at microwave frequencies the operating range is dramatically reduced compared to