Design and implementation of a passive UHF RFID tag with a temperature and process compensation oscillator

Abstract

A fully integrated passive UHF RFID tag chip compatible with ISO18000-6B protocol is pre- sented. In order to save die area, an all CMOS transistor regulator is adopted. An NMOS based traditional Dickson rectifier is employed with the advantage of circuit simplicity. An ultra-low power ring oscillator with temperature and process compensation is designed to guarantee the accuracy of the clock, which has a direct impact on the accuracy of backscatter link frequency (BLF). By utilizing several low power design approaches, a low power baseband processor is achieved. The whole tag chip is fabricated in TSMC 0.18m CMOS technology and the chip size is 730m × 605m. Measurement results show that the total power consumption of the tag is about 7W with a sensitivity of −13.1 dBm and an operational range of about 7.5 m under 4 W effective isotropic radiated (EIRP) power, and the accuracy of BLF is within ±10%. With the long operational range, the tag is suitable for many commercial applications, such as supply-chain and logistics managements as well as location sensing system.