An Efficient and Fast Reverse Buck Converter for High-Power Envelope-Tracking Systems

This paper presents an efficient and fast reverse buck converter targeting high-power envelope-tracking applications with up to 20MHz instantaneous bandwidth. The power stage is based on RF power GaN-HEMT technology. Operated from 40 V and switching at 80 MHz, a maximum output power of 125W is demonstrated for 82% duty cycle. The maximum overall efficiency including the switch driver losses is in the range of 91 % to 86 % for switching frequencies between 50 MHz and 110 MHz. The reverse buck converter is evaluated in terms of switching behavior, output filter characteristics, output voltage and efficiency, always considering that it is loaded with varying impedances under envelope tracking operation.