A common mode filter includes an inner coil and an outer coil. The inner coil is formed of an inner wire and includes a plurality of inner turns. The outer coil is formed of an outer wire and includes a plurality of outer turns and at least one cross turn. A sum of the plurality of outer turns and the at least one cross turn is equal to a number of the plurality of inner turns, and the at least one cross turn comprises a N-th turn of the outer coil wound across a (N−1)th turn of the outer coil, and adjacent to two of the plurality of turns of the outer coil.