RF-energy harvesting and wireless power transfer efficiency from digitally modulated signals

The RF-DC conversion efficiency of an RF harvesting circuit when it is excited by digitally modulated signals is investigated. A variety of signals with the same average power but different complementary cumulative distribution function (CCDF) and peak-to-average-power ratio (PAPR) properties are applied at the input of a prototype UHF diode rectifier. The rectifier is optimized for maximum efficiency under low average input power levels and the RF-DC conversion efficiency for different output load conditions is evaluated. It is shown that depending on the CCDF and PAPR properties of the applied signal a different optimum load exists which leads to a maximum efficiency.