US Patent 7852185 On-die micro-transformer structures with magnetic materials

A transformer integrated on a die, the transformer comprising a set of conductive lines formed on the die within one layer and interconnected among each other so that no two lines belonging to any one winding are nearest neighbors. The set of conductive lines is surrounded by a magnetic material, which may be amorphous CoZrTa, CoFeHfO, CoAlO, FeSiO, CoFeAlO, CoNbTa, CoZr, and other amorphous cobalt alloys. The transformer may be operated at frequencies higher than 10 MHz and as high as 1 GHz, with relatively low resistance and relatively high magnetic coupling between the windings.