Abstract: The present invention relates to a power converter device (1) comprising; a first circuit board (100), the first circuit board comprising a first driver (102) and at least four GaN HEMT devices (101) arranged in pairs (103, 104), said pairs connected in parallel; a second circuit board (200), the second circuit board comprising a second driver (202), and at least four MOSFET devices (201) arranged in pairs (203, 204), said pairs connected in parallel; the power converter device comprises at least two electrical connections (20) between the two circuit boards; wherein the first circuit board extends in a first plane and the second circuit board extends in a second plane, and the first and second circuit boards are arranged one above the other such that the two planes extends in parallel and the electrical connections between the two circuit boards extends in a direction substantially perpendicular to said first and second planes; and wherein said at least four GaN HEMT devices (101) are electrically connected