Patent attributes
The present invention relates a laminated balun transformer with an improved insertion loss characteristic in a pass band. The laminated balun transformer includes a first strip line and a third strip line form one coupler, a second strip line and a fourth strip line form another coupler, and a conductive non-ground electrode formed at an intermediate position between the third strip line and the fourth strip line. The non-ground electrode forms a ground by electromagnetic coupling between the third strip line and the fourth strip line. With the configuration, insertion loss in an operation band is reduced. In addition, by implementing an impedance and an electromagnetic shield using a ground pattern of a mount surface without separately forming an internal ground electrode on the bottom layer of a dielectric block, of ground electrodes formed above and below the first to fourth strip lines for the electromagnetic shield from the outside, the thickness of the laminated balun transformer can be reduced without any deterioration of characteristic of the transformer.
