A dual-band high-efficiency rectifier based on high-quality interleaved micro-strip inductor for energy harvesting systems

A novel high-efficiency dual-band voltage doubler (VD) rectifier based on a high-quality micro-strip inductor is proposed for low-power energy harvesting (EH) systems. The suggested design operates in two frequency bands, the first band is matched utilizing slotted radial stubs and a novel high-quality interleaved 8-shaped micro-strip inductor to work at 1 GHz, while the second band is matched employing an off-the-shelf inductor connected to a diode anode to operate at 1.3 GHz. The new interleaved inductor provides the benefits of a compact size and high-quality factor, reducing area by 70 %, while maintaining a quality factor of 120 and an inductance of 22 nH at 1 GHz. Unlike conventional inductors that use an inductor width ratio of 1, the proposed inductor employs a width ratio of 1.42 to maximize the Q-factor. The radial stubs with circular slots are employed to improve the input reflection coefficient, enhance conversion efficiency, and increase the DC-output voltage. The second band matching at 1.3 GHz is obtained by a real discrete inductor linked to the diode anode, considering the inductor parasitic capacitance to match this band. The proposed VD rectifier achieves an extreme simulated efficiency equal to 72 %, a saturated output DC-voltage equal to 3.5 V, while the extreme measured RF-DC efficiency is equal to 61 %, saturated voltage equal to 3.5 V, and the measured efficiency at -10 dBm input power ($P_{\mathrm{in}}$) is 46 % and 37 % for frequency bands of 1 and 1.3 GHz. The measured DC-voltage at -10 dBm input power is 0.6 V and 0.53 V for dual bands. The suggested voltage doubler rectifier occupies a PCB board size of $2.6cm\times 1.8cm$ ($4.9c{m}^2$).