One aspect of the invention relates to a symmetrical transformer with a stacked coil structure comprising two coils each having at least two turns. The coils are located in two conductive planes. The structure includes four identical basic elements, each basic element providing a conductive path for part of the coils. The terminals of the transformer are located at opposite sites of the structure so that the structure can be easily connected in a chain. The invention also relates to a semiconductor device comprising such a structure.