A 48 V, 300 kHz, High Current DC/DC-Converter Based on Paralleled, Asymmetrical & Thermally Optimized PCB Embedded GaN Packages with Integrated Temperature Sensor

To make the full performance of the intrinsic 100 V, 5mΩ gallium nitride transistors available on system level, in this work an asymmetrical & thermally optimized PCB embedded single chip package with integrated resistance thermometer, high temperature capability and a thermal resistance R th,j–hs of 3.3KW ⁻¹ is characterized in a 48 V to 24 V 300 kHz mild-hybrid DC/DC operation with two paralleled chips in each low- (LS) and high-side (HS). The transistors are mounted on a 4-layer multilayer PCB with 1 mm copper inlays to achieve a high current capability, while allowing narrow logic traces on the same PCB. The designed converter is achieving a light load efficiency of ≥99 % and an efficiency of 97 % at 60 A output current and ≈1.3 kW output power in a 48 V to 24 V 300 kHz buck-converter operation. The on-board temperature readout circuit and the phase output current sensor offer the possibility to extend the GaN transistors to an intelligent power module by the compact and simple sensors.