A fully-autonomous integrated rf energy harvesting system for wearable applications

In this paper we introduce a complete system architecture of a textile-based rectenna loaded by a novel power management platform able to be autonomously activated by ambient RF energy harvesters. An integral design approach of the system blocks is carried out to provide the actual nonlinear behavior of the rectenna output, which is a function of the operating frequencies and power levels, as the DC-DC converter input. The RF properties of the textile rectenna are computed by nonlinear techniques with textile materials and antenna layout numerically characterized by means of EM simulations. A novel integrated power converter is adopted. It is equipped with a start-up circuit and an energy storage unit and it is designed by microelectronic technology. Energy autonomy of the entire system, including a battery-less activation is expected for RF available power levels as low as -15 dBm. The system operation is computed with the wearable rectenna recovering RF energy upon user request from GSM 900, GSM 1800 and WiFi sources.