High PAPR Multi-Tone Waveforms as a Method of Boosting DC voltage in RF Wireless Power Transfer Systems

A DC voltage boosting technique in radio frequency (RF) wireless power transfer (WPT) systems is proposed. This technique utilizes high PAPR multi-tone waveforms. It is demonstrated that increased efficiencies and DC voltages can be achieved for conventional single- and multi-stage rectifiers. First, the use of multi-stage rectifiers in wireless power transfer as a method to increase the DC output voltage is investigated and it is shown that at low input powers the implementation of a large number of stages can reduce the efficiency dramatically. Then, high PAPR waveforms are presented as an alternative method to multi-stage rectifiers that can increase the DC output voltage without decreasing the efficiency at low input powers. Finally, it is shown that by incorporating high PAPR waveforms with multi-stage rectifiers can decrease the required number of rectifier stages, and hence increase the rectifier efficiency at extremely low input powers.