Rectenna with Serially Connected Diodes for Micro-watt Energy Harvesting

This paper shows that RF-DC charge pumps can become identical to a single equivalent diode model to have input power as low as possible at a fixed output voltage and current condition in micro-watt energy harvesting. Circuit conversion from rectenna with multiple diodes connected in series to that with the equivalent model is presented. The proposed model was validated with ADS simulation. The simulation showed that rectenna with two diodes connected in series could have power conversion efficiency of 37%, which is higher than that of 31% for one-stage RF-DC charge pump and that of 27% for rectenna with a single diode at an output voltage of IV and an output current of 10μA when Skyworks SMS7621 is used for diodes at 2.45GHz.