150 V-Bias RF GaN for 1 kW UHF Radar Amplifiers

A 1 kilowatt pulsed RF amplifier operating at 150 V for radar applications in the UHF frequency band from 420 MHz to 450 MHz is presented. GaN HEMT devices with 600 V breakdown voltage are becoming ubiquitous in power conversion applications operating from kHz to a few MHz, but they have never been considered for RF applications in power amplifiers. This paper explores the advantages in high power RF amplifiers that employ a high voltage GaN technology operating above the industry standard of 50 V. The signal is a pulse of 100 μs width and 10% duty cycle. The power amplifier is based on a specifically designed RF GaN technology that can operate at 150 V bias. The RF GaN transistor has breakdown voltage in excess of 500 V and peak iron (Fe) doping in the buffer layer in excess of 10
¹⁸
cm
^-3
. The single- ended 150 V RF GaN device utilizes three dice of 15 mm gate periphery assembled in a standard ceramic package. It achieves 1 kW output power across the band, with >70% drain efficiency without pulse gating during radar transmitter receive mode.