Design of Efficient Rectifier Circuit for Electromagnetic Energy Harvesting Under Low Input Power Conditions

This paper presents a structurally simple rectifier design for harvesting electromagnetic (EM) energy in extremely low microwave (MW) power density environments. The low forward voltage Schottky diode SMS7630 is used as the key rectifier component. A simple impedance matching network is designed using Smith Chart specifically for working at −20 dBm input power level. The measurement results show that when the input MW power is −20 dBm and the direct-current (DC) load is 4 kΩ, the proposed rectifier circuit can achieve a MW-DC conversion efficiency of 21.6% at 2.45 GHz. It even can output a net positive DC voltage at extremely low input power of −36 dBm. The proposed rectifier can be easily integrated with efficient flexible antennas to drive low-power wearable sensors.