A RF Energy Supply Method for End Nodes in Smart Buildings

The application of Internet of Things in smart buildings is becoming more and more extensive. The energy supply problem of end nodes has always been a concern of the field of research and industry areas, and an adaptive radio frequency energy conversion system is proposed for the low power node of the Internet of Things. By using the unipolar transistor control, the threshold voltage of the rectifier changes dynamically, through RF matching, and double voltage rectification measures the supply for the low power nodes. The proposed circuit is aimed at reducing the threshold voltage of the transistor forward bias to increase power and output voltage of the harvester and increasing the reverse bias of the threshold voltage for reducing the leakage current. It prevents the loss of stored energy. This paper presents a 12 stages adaptive threshold-compensated rectifier circuit has reached the maximum power conversion efficiency 35.3% at -14 dBm. Meanwhile, when the input power is -12dBm, the output voltage is 3.2 V at the output load 1 MΩ. The low power characteristics of the nodes at the end of the Internet of Things make it possible to convert the RF energy into electric energy.