Design Of Low-voltage Passive UHF RFID Tag And Study On Schottky Diode

In recent years, with the rapid development of wireless communication technology, radio frequency identification (RFID) market is gradually on the rise. RFID is an automatic identification technology, which transfer data between tag and reader in the use of radio frequency electromagnetic waves. Especially UHF radio frequency identification (UHF RFID) applications have developed rapidly.This paper focuses on the design of low-power passive UHF RFID tag. Firstly, the RFID system structure and the fundamentals are discussed, and the relevant protocols are compared. The system architecture of the passive UHF RFID tag is analyzed. Secondly, the RF front-end of the UHF RFID is analyzed in theory, and the circuit has been optimized. And the input impedance of the tag is estimated which is based on the practical circuit. Furthermore, the low-power analog front-end of the UHF RFID tag is studied, which includes regulator,ASK demodulator,reference,oscillator and POR. Especially, a low-power starved ring oscillator is introduced, which effectively reduce the power of the tag and increase the reading distance.The low-voltage passive UHF RFID tag is designed in Chartered 0.35μm two-poly four-metal (2P4M) CMOS process, which is compatible with the ISO 18000-6 Type B standard. To achieve the low-power, the operating voltage is 2.5V, while the standard operating voltage is 3.3V. And Sub-threshold technology is chosen. The simulation and calculate results show that the chip's reading range is more than 4m at the 920 MHz ISM band, and the current of the RF AFE circuit is less than 7μA. The tag meets the requirements of the design specifications.In order to get low cost and high performance chip, a Schottky diode using standard CMOS process is designed and fabricated with SMIC 0.18μm CMOS process. Finally a simulation model is built.