Microwave Rectifiers Using Resonant Inductors to Enhance Sensitivity to Low Input Power

A low-power rectifier for RF energy harvesting based on a novel operating principle is presented. The proposed diode rectifier integrates an external series inductor that resonates with the diode's parasitic capacitances. This resonance enhances the electromotive force of the inductor, amplifying the RF input signal. As a result, the finite threshold voltage of silicon-based Schottky barrier diodes (SBDs) is effectively reduced, improving their sensitivity to weak environmental RF signals. Prototype rectifiers designed to operate at single and multiple resonant frequencies were fabricated using commercial discrete SBDs. These prototypes exhibited notably high RF-to-DC power conversion efficiencies at an RF input power of -20 dBm, achieving, for example, 38% efficiency at 700MHz and an average efficiency of 21.6% across the 0.43-0.77 GHz band.