Compact Voltage Doubler Rectifier for RF Energy Harvesting in Wearable Biomedical Devices

A compact voltage doubler rectifier for RF energy harvesting (RFEH) in wearable biomedical devices (WBDs) is designed to operate at 2.45 GHz. The rectifier features a shortcircuit shunt stub for impedance matching, a diode-based rectification module, and a rectangular square-wave DC smoothing filter to refine the rectified signal. The compact rectifying circuit is fabricated on an RT/duroid 5880 substrate with dimensions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$33 \text{mm} \times 13 \text{mm}$</tex>. Experimental evaluations demonstrate that the proposed rectifier achieves a Power Conversion Efficiency (PCE) of 38 % at -5 dBm and 16 % at -20 dBm with a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5 \mathrm{K} \Omega$</tex> load resistance. The rectifier's high sensitivity at low input power makes it suitable for powering various WBDs. This work contributes to the advancement of efficient RFEH solutions for wearable biomedical applications.