RF-Only Logic: an Area Efficient Logic Family for RF-Power Harvesting Applications

Reducing circuit design cost and eliminating over-design margin are the two challenges for advancing the Internet of Things (IoT). An RF-dc rectifier and storage capacitors consume 25% or more of the chip area for cost-sensitive power-harvesting-enabled IoT applications. In this paper, we explore a new circuit structure called RF-only logic that permits logic circuits to operate directly from an un-rectified RF source. By eliminating the need for RF-dc rectifier and storage capacitors, RF-only logic helps to reduce cost and design complexity for power-harvesting-enabled applications. The structure and operations of RF-only logic are presented. Its performance, power consumption, and robustness are analyzed through simulation and validated with measurement results. A standard cell library was developed for RF-only logic, and an algorithm was implemented to further improve area efficiency. A ring oscillator and two 4 x 4 multipliers were fabricated in 0.13-mu m CMOS as test structures. The ring oscillator was functionally measured with an RF supply voltage down to 100-mVrms at 1 GHz. The multipliers demonstrate performance improvement and overall area overhead of 16% by implementing the power-supply transistor sharing algorithm.