A UHF Near-Field RFID System With Fully Integrated Transponder

This paper presents an RF identification (RFID) system with a fully integrated transponder. To enable the on-chip integration of the tag's antenna, it is suggested to employ near-field coupling at high-frequency ranges, i.e., the UHF band. The RFID system including the reader and key blocks of the transponder is designed and fabricated in a standard CMOS 0.18-mum process. The system operates at 900 MHz with the coverage range of over 0.4 cm. The tag's antenna is integrated on-chip without using any special process. The reader employs multiple coils to increase its coverage area. Using a proper output network, the reader can deliver a current of 225 mA (rms) to its coil, which is designed on a printed circuit board.