Circuit board, defining a plurality of switching arms connected in parallel so as to convert a first voltage into a second voltage, at least one of which is DC voltage. The board includes a plurality of controllable electronic switches mounted pairwise in series on either side of a midpoint, so as to produce the switching arms connected in parallel. A plurality of decoupling capacitors are connected in parallel to one another, and in parallel to the DC voltage. Two electrically conductive layers are arranged parallel to one other, one of which is at the highest potential of the DC voltage and the other of which is at the lowest potential of the DC voltage. Each of the decoupling capacitors having one terminal connected to one of these electrically conductive layers and its other terminal connected to the other of these electrically conductive layers.