Design of High-Efficiency Octave-Bandwidth Single-Diode Rectifier Using Synthesized Elliptic Low-Pass Matching Network

This letter presents a novel methodology for designing a compact flat- and high-efficiency single-diode rectifier within an octave bandwidth for low-power energy harvesting (EH) systems. The proposed structure consists of a$1:n$transformer and a broadband elliptic low-pass filter. The former reduces diode impedance magnitude, which facilitates fundamental wideband matching with low insertion (IL) loss. Meanwhile, the latter with its sharp roll-off characteristic is manipulated to provide efficient fundamental matching and harmonic suppression simultaneously across the entire bandwidth, maintaining uniform optimal efficiency. With this design concept, a low-power rectifier over a 0.7–1.3-GHz bandwidth is designed and prototyped for verification, showing that an optimal power conversion efficiency (PCE) above 60% with a peak of 72.1% is sustained from 0.67 to 1.3 GHz at a 2-dBm input power, corresponding to a fractional bandwidth (FBW) of 63.9%. Also, an average PCE of 68.2% is recorded across the target bandwidth with only a small standard deviation of 2.7%, indicating a stable broadband operation. Furthermore, the proposed rectifier has a miniature size of$26\times 12$mm.