A device includes a core having a first end and a second end, and first and second wires wound around the core, where the core has first, second, and third sections, the second section being arranged between the first and third sections. Each of the first and second wires includes an ith turn located on the first section, a jth turn located on the second section, and a kth turn located on the third section. The ith turn of the first wire is closer to the first end than the ith turn of the second wire, the jth turn of the first wire is closer to the second end than the jth turn of the second wire, and the kth turn of the first wire is closer to the first end than the kth turn of the second wire.