Experimental evaluation of direct liquid cooling on GaN HEMT based power amplifier MMIC

We describe the use of direct liquid cooling to improve the performance of an X-band GaN HEMT based power amplifier Monolithic Microwave Integrated Circuit. With improved cooling, the operating drain bias was increased from 20V to 44V and the PA MMIC delivered 5.1W/mm power density while dissipating 8.9W/mm of thermal power under continuous wave operating condition.