Multilayer balun

A multilayer balun comprising:

• an unbalanced port;
• a first balanced port;
• a second balanced port;
• a first line connected to the unbalanced port;
• a second line connected in series to the first line;
• a third line connected to the first balanced port and electromagnetically coupled to the first line;
• a fourth line connected to the second balanced port and electromagnetically coupled to the second line;
• and
• a stack for integrating the unbalanced port, the first and second balanced ports, and the first to fourth lines, wherein
• the stack includes a plurality of dielectric layers and a plurality of conductor layers stacked on each other,
• the plurality of conductor layers include a plurality of line-forming conductor layers and at least one ground conductor layer connected to a ground,
• the plurality of line-forming conductor layers include a plurality of first conductor layers forming the first and third lines and a plurality of second conductor layers forming the second and fourth lines, and include a plurality of conductor layer pairs each including two conductor layers adjoining in a stacking direction of the plurality of dielectric layers and the plurality of conductor layers, the two conductor layers being electromagnetically coupled to each other,
• the plurality of first conductor layers are located in a first region in the stack,
• the plurality of second conductor layers are located in a second region in the stack, the second region being located at a position different from the first region in the stacking direction,
• the at least one ground conductor layer is located at a position different from the first and second regions in the stacking direction and closer to the second region than to the first region, and
• the plurality of second conductor layers include at least one conductor layer pair where a distance between the two conductor layers is smallest among the plurality of conductor layer pairs.