This paper presents a 5.8 GHz RF-DC converter for high conversion efficiency and high output voltage based on a common-ground and multiple-stack structure. An RF isolation network (RFIN) for the multiple-stack RF-DC converter is proposed to combine the DC output voltage of each stack without separating its RF ground from the DC ground. The RFIN is designed using micro-strip transmission lines on a single-layer printed circuit board (PCB) with a common ground for the bottom plate. A 4-stack RF-DC converter based on a class-F voltage doubler for each stack was implemented to verify the proposed RFIN for the multiple-stack and common-ground structure. The performances of the implemented 4-stack RF-DC converter were evaluated in comparison to the single-stack converter that was also implemented. The size of the implemented 4-stack RF-DC converter using bare-chip Schottky diodes is 24 mm × 123 mm on a single-layer PCB. For an input power of 21 dBm for each stack of the RF-DC converter with a load resistance of 4 kΩ, a high efficiency of 73.1% and a high DC output voltage of 34.2 V were obtained.
Keywords: RF isolation network; microwave power transfer; multiple-stack RF–DC converter; rectenna array; rectifier; voltage doubler.