sensors Article A Long-Distance RF-Powered Sensor Node with Adaptive Power Management for IoT Applications Matteo Pizzotti 1,2,* ID , Luca Perilli 1 ID , Massimo del Prete 2, Davide Fabbri 2, Roberto Canegallo 3, Michele Dini 1, Diego Masotti 2 ID , Alessandra Costanzo 1,2, Eleonora Franchi Scarselli 1,2 ID and Aldo Romani 1,2 ID 1 Advanced Research Center on Electronic Systems, University of Bologna, Via Toffano 2/2, Bologna 40126, Italy;
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[email protected] (A.R.) 2 Department of Electrical, Electronic, and Information Engineering, University of Bologna, Via Risorgimento 2, Bologna 40126, Italy;
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[email protected] (D.M.) 3 STMicroelectronics, Via Camillo Olivetti, Agrate Brianza 20864, Italy;
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[email protected]; Tel.: +39-054-733-9537 Received: 30 June 2017; Accepted: 26 July 2017; Published: 28 July 2017 Abstract: We present a self-sustained battery-less multi-sensor platform with RF harvesting capability down to −17 dBm and implementing a standard DASH7 wireless communication interface. The node operates at distances up to 17 m from a 2 W UHF carrier. RF power transfer allows operation when common energy scavenging sources (e.g., sun, heat, etc.) are not available, while the DASH7 communication protocol makes it fully compatible with a standard IoT infrastructure. An optimized energy-harvesting module has been designed, including a rectifying antenna (rectenna) and an integrated nano-power DC/DC converter performing maximum-power-point-tracking (MPPT).