Quest for vacuum tubes' replacement: 150 V UHF GaN radar transistors

This paper analyzes the requirements for solid-state devices to replace vacuum tubes in radar systems and introduces a 700 W GaN transistor operating at 150 V at UHF frequencies with 80% drain efficiency. The signal during the RF tests employed 52 μs and 100 μs pulse width with a duty cycle ranging from 2% to 5% and 10% at a frequency of 430 MHz. Although the prototype transistor presented in this paper consists of only two chips inside a small package with 30 mm total gate periphery, it can easily be scaled up to larger periphery and a larger package for power in the 2 kW-3 kW range. This is believed to be the first demonstration of RF solid-state devices operating at 150 V ever reported for UHF radar systems.