GaN Transistors Cooling Options Comparison

Three methods of cooling gallium nitride (GaN) transistors have been tested and directly compared together. Under similar conditions, top side cooled GaN was compared to the bottom side cooled type; both were of the same electrical parameters and were mounted on FR4 (fibreglass resin) and IMS (insulated metal substrate) printed circuit boards. At equal dissipated power the proposed bottom side cooled transistor on IMS board reaches half the temperature compared to the top side cooled one and one fourth of the temperature compared to the bottom side cooled GaN on FR4 board. A High speed driver is placed close to the transistor also on the IMS board to reduce parasitic inductance of the gate driving path from control board to the high power side on the IMS board.