Power GaN FET boards thermal and electromagnetic optimization by FE modeling

This work deals with optimization of boards with commercial discrete power GaN FETs in applications where natural air convection is a strict constraint. In these cases, both thermal and electromagnetic behaviours are critical reliability issues for the board design, and they are modeled by Finite Element (FE) analysis, starting from literature description of the device structure, and measurements on a simple test circuit. For improved accuracy and more realistic modeling, verification and validation simulation steps are introduced, in order to evaluate the relevant error parameters for different FEM solutions. The results obtained demonstrate a good fitting with experimental and make it possible to improve board thermal characteristic. The electromagnetic simulations allow the evaluation, and possibly the reduction, of parasitic inductances for different layouts. Then, the proposed approach enables thermal and electromagnetic optimization of the layout design by simple FEM simulations, without any preliminary prototype, with time and cost saving.