Passive Impedance-Tracking Rectifier for efficient Deep Sub-Threshold RF Energy Harvesting

<title>Abstract</title> <p>We present a passive impedance-tracking matching strategy that resolves the critical efficiency drop-off observed in deep sub-threshold (-30 to -10 dBm) RF energy harvesting. Conventional rectifiers typically suffer from a "semiconductor sensitivity cliff" due to theexponential divergence of diode impedance at low power. To counter this, we utilize a Genetic algorithm (GA) to synthesize afixed L-match network that approximates the diode’s complex conjugate trajectory over a 20 dB dynamic range. Unlike active tuning circuitsthat consume overhead power, our solution is purely passive. Simulation at 915 MHz reveals that this approach sustains &gt;90% transmissionefficiency throughout the target window, yielding a 93.5 percentage point efficiency gain over standard fixed-matching baselines at -30 dBm.Monte Carlo analysis further validates the design, showing 100% yield under standard manufacturing tolerances.</p>