Patent ID: 8054155

Claim:
A symmetrical transformer with a stacked coil structure comprising a primary and a secondary coil each having at least two turns, the primary and secondary coils being located in a first and a second conductive plane which are electrically isolated from each other by an intermediate dielectric layer, the primary and secondary coils being electrically isolated from each other and being arranged so that magnetic coupling takes place between them, wherein the structure comprises four identical basic elements, each basic element providing a conductive path for part of said coils the first conductive plane comprising a first of said basic elements and a second of said basic elements electrically isolated from each other, the first basic element providing half of the turns and a first terminal of the primary coil, the second basic element providing half of the turns and a second terminal of the secondary coil, the first terminal of the primary coil and the second terminal of the secondary coil being located on opposite sides of the structure, the second conductive plane comprising a third of said basic elements and a fourth of said basic elements electrically isolated from each other, the third basic element providing half of the turns and a third terminal of the secondary coil, the fourth basic element providing half of the turns and a fourth terminal of the primary coil, the fourth terminal of the primary coil and the third terminal of the secondary coil being located on opposite sides of the structure, the first and fourth terminal of said primary coil being located on the same side of the structure and in different planes from one another, the second and third terminal of said secondary coil being located on the same side of the structure and in different planes from one another, an end of the first basic element being electrically connected to an end of the fourth basic element by a first connection through the dielectric layer, an end of the second basic element being electrically connected to an end of the third basic element by a second connection through the dielectric layer.