Wirelessly powering: An enabling technology for zero-power sensors, IoT and D2D communication

Wireless power transfer (WPT) is foreseen as a key enabling technology for energy-autonomous wireless sensors, Internet of Things and Device to Device communication. RF energy, either scavenged from the ambient or intentionally provided to a wireless device, can be successfully exploited for autonomously sustaining its operations. In this paper we overview the main aspects to be addressed for a successful design of a far-field WPT system. The end-to-end circuit level co-design of the WPT link is described as the procedure to effectively address the system optimum efficiency. Specific selection of antenna elements and active sub-circuits are analyzed, depending on the power levels involved and on the specific application environment. The base-band design of the power management unit used to dynamically provide the receiver with optimum loading conditions is also analyzed.