Abstract: A coupled inductor includes a magnetic core, a first and a second coil. The magnetic core has a top and a bottom surface. The first coil, located in the magnetic core, has a first coil input end and a first coil output end, and is wound around a first axis in a first winding direction from the first coil input end and extended to the first coil output end. The second coil, located in the magnetic core, has a second coil input end and a second coil output end, and is wound around a second axis in a second winding direction, opposite to the first winding direction, from the second coil input end and extended to the second coil output end. An orthographic projection of the first coil on the top surface is at least partially overlapped with that of the second coil on the top surface.