Ultra-efficient microwave harvesting system for battery-less micropower microcontroller platform

The experimental results of a micro-powered 2.45 GHz voltage multiplier with and without the charge-pump integrated circuit (IC) driving a microcontroller on FR-4 are presented. Five different rectifier designs are built and compared under different input power levels. Results show that a multi-stage voltage multiplier delivers higher voltage levels to the microcontroller without the need for the charge-pump IC. However, a single-diode design performs best when the charge-pump IC is present. The measurement results show that the energy harvesting system can provide 2 V to turn on the microcontroller with only 15.6 dBm (27.5 W) radio frequency input power and that the battery-less microcontroller can be wirelessly powered when located up to a distance of 57 cm from a transmitter supplying a total of just 100 mW of microwave power.