Laminated balun transformer
AssigneeMurata Manufacturing Co., Ltd.
InventorsHirokazu Yazaki, Atsushi Toujo
Life of this patent
Estimating the term…
Abstract
A laminated balun transformer includes a third line element and a first line element which are electromagnetically coupled at a coupling portion to define a first coupler. A second line element and a fourth line element are electromagnetically coupled at a coupling portion to define a second coupler. When the length of a λ/4 line element at a given characteristic impedance is L(0), the length of the coupling portion of the first and third line elements, which are electromagnetically coupled, is L(0)+α and the length of the coupling portion of the second and fourth line elements, which are electromagnetically coupled, is L(0)−β, where α and β satisfy the relationships α>0, β>0, and α=β or α≠β.
Claims20
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 λ/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)+α 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)−β, where α>0 and β>0.
A laminated balun transformer having an input impedance less than the output impedance thereof, 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
- the third line element, which is electromagnetically coupled with the first line element, is connected to an input terminal of the laminated balun transformer, and the second and fourth line elements, which are electromagnetically coupled, are connected to two output terminals, respectively, and
- wherein, when the length of a λ/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)+α 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)−β, where α>0 and β>0.
Dependencies are inferred from the claim text.