A broadband high efficiency rectifier for ambient RF energy harvesting

Ambient energy harvesting is a key technology to the success of wireless sensor networks. Among various energy sources available in daily environment, electromagnetic RF energy is a good source due to the wide signal coverage from various wireless communication systems. Harvesting a wide frequency band RF signals is useful to boost the total energy level. In this paper, a broadband high efficiency RF rectifier with a shunted Schottky diode is presented. The source pull simulation is used to find the optimal source impedance over the wide frequency range while maintaining good conversion efficiency. A 3^rd transmission line low-pass matching network is designed to realize the optimal source impedance. The measurement results agree well with the simulation results. The highest measured efficiency is 81% and a frequency band 0.78-1.43 GHz with efficiency exceeding 50% is achieved for an input power level of 25 mW.