RESUMEN
This paper proposes a class-F synchronous rectifier using an independent second harmonic tuning circuit for the power receiver of 2.4 GHz wireless power transmission systems. The synchronous rectifier can be designed by inverting the RF output port to the RF input port of the pre-designed class-F power amplifier based on time reversal duality. The design of the class-F power amplifier deploys an independent second harmonic tuning circuit in the matching networks to individually optimize the impedances of the fundamental and the second harmonic. The synchronous rectifier at the 2.4 GHz frequency is designed and implemented using a 6 W gallium nitride high electron mobility transistor (GaN HEMT). Peak RF-dc conversion efficiency of the rectifier of 69.6% is achieved with a dc output power of about 7.8 W, while the peak drain efficiency of the class-F power amplifier is 72.8%.
RESUMEN
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.
RESUMEN
The synthesis of isoxazoles has been achieved in a continuous flow system composed of two reaction units: the Friedel-Crafts acylation of alkynes and the azide conjugate addition to the resulting ß-chlorovinyl ketones followed by a photochemical-thermal reaction sequence. The salient feature of the current flow system includes the safe handling of potentially explosive organic azide species as well as the rapid conversion of batch reactions into flow conditions with the integration of multiple reactor units.