Patent ID: 8400249

Claim:
A common mode choke coil comprising: a first transmission line; a second transmission line paired with the first transmission line; a first coil element connected in series to the first transmission line; a second coil element connected in series to the first transmission line; a third coil element connected in series to the second transmission line and coupled to the first coil element; and a fourth coil element connected in series to the second transmission line and coupled to the second coil element, and wherein winding directions and connection directions of the first coil element, the second coil element, the third coil element, and the fourth coil element are determined such that, with normal mode current flow through the first and second transmission lines, a first closed magnetic circuit forms in which a magnetic flux passing through the first coil element and the second coil element forms a closed loop and a second closed magnetic circuit forms in which a magnetic flux passing through the third coil element and the fourth coil element forms a closed loop, and, with common mode current flow through the first and second transmission lines, a third closed magnetic circuit forms in which a magnetic flux passing through the first coil element, the second coil element, the third coil element, and the fourth coil element forms a closed loop.