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

摘要

A fully integrated passive UHF RFID tag chip compatible with ISO18000-6B protocol is presented. 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 0.18 μm CMOS technology and the chip size is 730 μm × 605 μm. Measurement results show that the total power consumption of the tag is about 7 μW with a sensitivity of -13.1 dBm and an operational range of about 7.5 m under 4W 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.