Effects of the Temperature on the Efficiency Degradation in Multi-stage RF Energy Harvesters

The conversion efficiency of a multi-stage RF energy harvester on a printed circuit board charge-pump, based on off-the-shelf diodes and capacitors is studied, in the UHF band, as a function of temperature. The considered temperature range varies from 25°C to 85°C, highlighting that the effects of the temperature may cause a severe degradation on the harvested power, in particular at the lowers incident power regimes. Experimental measurements are presented to show that the rectifiers quality has the biggest impact of the harvester performances. Precisely, the temperature dependent rectification ratio of silicon Schottky diodes commonly used for this application can be considered as a quality factor of the converter.