Patent ID: 7579923

Claim:
A laminated balun transformer comprising: a first magnetic substrate; a laminated body including a first transformer and a second transformer, each of which includes a primary coil and a secondary coil that are laminated on the first magnetic substrate and that face each other; and a second magnetic substrate provided on the laminated body; wherein one end of the primary coil of the first transformer defines an unbalanced terminal and the other end of the primary coil defines a first balanced terminal, one end and the other end of the secondary coil respectively define ground terminals, one end of the primary coil of the second transformer is connected to the one end of the primary coil of the first transformer and the other end of the primary coil of the first transformer is connected to the secondary coil of the first transformer, one end of the secondary coil of the second transformer is connected to the one end of the secondary coil of the first transformer and the other end of the secondary coil of the second transformer defines a second balanced terminal; and a shape of the primary coil of the first transformer is set such that a line width of the primary coil of the first transformer increases or decreases from the one end towards the other end, and a shape of the secondary coil of the second transformer is set such that the line width of the secondary coil of the second transformer increases or decreases from the one end towards the other end.