Enhanced Stability Analysis of Parallel Connected GaN-Transistors in Half-Bridge Circuits

In high current power electronics applications, power transistors are often connected in parallel to enhance the efficiency and achieve higher system power. When connecting power transistors in parallel, resonant circuits caused by the parasitic parameters of the printed circuit board (PCB) and the transistor itself occur. These resonant circuits cause oscillations, resulting in higher switching losses or even damage to the device. This paper describes an approach to detect and suppress oscillations when connecting two gallium nitride (GaN) High Electron Mobility Transistors (HEMTs) in parallel. The analytical model shows the influence of parameter variation of source- and gate inductance on system stability. The simulation model verifies that parameter variation can strongly influence the oscillation behavior of the system. Finally, a hardware demonstrator is used to evaluate the analytical model and the simulation model.