Power Optimized Waveform for Wireless Power Transfer Systems : Simulations and Experiments

This paper focuses on the power optimization waveform, applied to the improvement of the efficiency and/or the maximum supply distance of far-field wireless power transfer systems. The emphasis is given to RF pulse modulation signal and multisine waveforms. The power conversion efficiency (PCE) of a RF-to-dc conversion circuits is strongly impacted by the threshold voltage of Schottky diodes at low RF power levels, and one of the objectives is to improve the efficiency under these conditions. An ultra-wide band rectifier, operating from 1.6 to 2.8 GHz, is used in this work. Significant improvement of the efficiency, compared to a CW signal, has been shown especially when the power level is small and the output load is large. Also, this work allowed evaluating the important parameters of the waveforms to be optimized.