Patent ID: 6628189
Filing Date: 2003-09-30
Classification: H01F,H03H

Abstract:
A laminated balun transformer to be mounted on a circuit board having a ground pattern, comprising:a laminate including first and second spiral line elements that define a pair of balanced transmission lines, third and fourth spiral line elements that define an unbalanced transmission line that is electromagnetically coupled with the balanced transmission lines; and a plurality of dielectric layers, wherein the first, second, third, and fourth spiral line elements, and the dielectric layers are laminated together; wherein when the laminated balun transformer is mounted on the circuit board, the distance from the second and fourth line elements, which are electromagnetically coupled, to the ground pattern is greater than the distance from the first and third line elements, which are electromagnetically coupled, to the ground pattern; and when the length of a &lgr;/4 line element at a given characteristic impedance is L(0), a coupling portion at which the first and third line elements are electromagnetically coupled has a length that is approximately equal to L(0)+&agr; and a coupling portion at which the second and fourth line elements are electromagnetically coupled has a length that is approximately equal to L(0)âˆ’&bgr;, where &agr;>0 and &bgr;>0.