Resistor Emulation Approach to Low-Power RF Energy Harvesting

摘要

This paper presents an approach and associated circuitry for harvesting near maximum output power from electromagnetic waves in the RF/microwave region of the spectrum with variable incident power densities in the range of tens of $mu$W/cm $^{2}$. It is shown that open loop resistor emulation at the input port of a power converter is a suitable solution for tracking the peak power point of a low-power rectifying antenna source over a wide range of incident RF power densities. A boost converter with a simple low-power control approach for resistor emulation is presented. A hardware design example with detailed efficiency analysis is given using commercially available discrete circuitry. Experimental results are presented for a system harvesting 420 $mu$W to 8 $mu$W from a 6 cm$,times,$ 6 cm rectifying antenna with incident RF power ranging from 70 $mu$W/cm $^{2}$ to 30 $mu$ W/cm$^{2}$, respectively. The results demonstrate that resistor emulation is a simple and practical approach to energy harvesting with variable low-power radiative RF sources.