A transformer device includes a first coil, a second coil, and a third coil. The first coil includes first segments and at least one first connecting portion, in which the first segments are coupled to each other through the at least one first connecting portion. The second coil includes second segments and second connecting portions, in which the of second segments are coupled to each other through the second connecting portions. The third coil is configured to couple the first coil and the second coil. The third coil includes third segments and third connecting portions, a part of the plurality of third segments are coupled in parallel with each other through the third connecting portions, and at least one part of the first segments and at least one part of the second segments are arranged between the part of the third segments.