AC-DC rectifier and storage capacitors take up 25% or more of chip area for cost-sensitive passive RFID tags. In this work, we show that these components can be eliminated by utilizing a RF-only circuit structure. Therefore, the chip would be smaller and cheaper. RF-only logic permits digital operations to be performed from an AC, rather than DC, power supply. An UHF Gen-2 compatible RFID tag is designed using the RF-only logic. Powering and communication solutions in direct ASK carrier powered scenario are developed. RF front-end circuits are designed in RF-only fashion and a standard cell library of RF-only logic is developed and tailored for this application. The RFID tag is implemented in a 0.13 μm CMOS technology. The tag dimensions are 0.6 mm × 0.3 mm and its sensitivity is 0 dBm at RF amplitude of 500mV in simulation. The same methodology can be applied to enable lower RF amplitude implementations that trade off area for sensitivity.
['Wenxu Zhao', 'Kirti Bhanushali', 'Paul D. Franzon']
Design of a rectifier-free UHF Gen-2 compatible RFID Tag using RF-only logic