A study on low power rectenna using DC-DC converter to track maximum power point

This study proposed a maximum power point tracking (MPPT) method for an mW low power RF-DC rectenna by using a DC-DC converter. The conversion efficiency of RF-DC rectifier circuit is affected by the load and the input power. In order to solve this problem, an RF-DC-DC circuit is proposed which consists of a RF-DC rectifier circuit and a DC-DC converter in this study. We designed a Buck-Boost converter with stable input impedance to match the optimal load of rectenna. The measured RF to DC efficiency of rectifier is almost steady at 75% in spite of the load resistance changed from 100 Ω to 5000 Ω when we connected the proposed Buck-Boost converter to the rectenna. The total efficiency of RF-DC-DC circuit is almost still over 60% even though the load resistance changed from 100 Ω to 5000 Ω with the input power of 82 mW.