Thermal Characterization and Management of GaN-on-SiC High Power Amplifier MMIC

Driven by the industry trends in radar applications, Gallium nitride (GaN) power amplifier (PA) has developed quite fast, targeting high performance needs, which in the meantime has posed critical challenge for device thermal management. Thermal design was started during the transistors and chip design. There are three stage transistors in the designed GaN PA chip. Thermal simulation correlated with IR camera experiment has been conducted for design, analysis and characterization of GaN-on-SiC Monolithic microwave integrated circuit (MMIC). Peak channel temperature and thermal resistance for DC and pulsed RF input operation have been investigated. The junction-to-case thermal resistance of the GaN chip under DC operation is 1.63°C/W, white thermal resistance is 1.05°C/W under pulsed operation. The validated model and results were used to guide the MMIC design, function test and reliability evaluation.