A Novel Dual-Band Rectifier Circuit with Enhanced Bandwidth for RF Energy Harvesting Applications

In recent years, a rapid development of low-power sensor networks, enabling machine-to-machine communication in applications such as environmental monitoring, has been observed. Contemporary sensors are normally supplied by an external power source, typically in a form of a battery, which limits their lifespan and increases the maintenance costs. This problem can be addressed by harvesting and converting ambient RF energy into DC power. In the paper, a novel dual-band rectifier circuit with high efficiency and enhanced bandwidth for RF energy harvesting applications is proposed along with its design procedure. The rectifier consists of two branches fed through a junction and two voltage doublers with a common DC output. The proposed structure is designed to work in 0.6 GHz to 1 GHz and 1.75 GHz to 2.45 GHz ranges with an average RF-to-DC conversion efficiency of at least 50 percent. Compact dimensions of 19 mm x 17 mm (a footprint of only 345 mm(2)) have been obtained through appropriate folding of the impedance transformers. As demonstrated, the proposed design outperforms state- of-the-art rectifiers in terms of the operational bandwidth, efficiency, and the range of acceptable load impedances.