Some implementations provide a coupled inductor structure that includes a first discrete inductor configured to generate a magnetic field, a second discrete inductor, and a first ferromagnetic layer coupled to the first discrete inductor and the second discrete inductor. The first ferromagnetic layer is configured to concentrate the magnetic field generated by the first discrete inductor within the coupled inductor structure. In some implementations, the coupled inductor structure further includes a second ferromagnetic layer coupled to the first discrete inductor and the second discrete inductor. The second ferromagnetic layer is configured to concentrate the magnetic field generated by the first discrete inductor within the coupled inductor structure. In some implementations, the coupled inductor structure is a bifilar inductor structure. The first discrete inductor includes a first set of windings and the second discrete inductor includes a second set of windings. The first and second discrete inductors share a common core.