Patent ID: 7504907

Claim:
A multilayer directional coupler comprising: a first magnetic substrate; a laminate laminated on the first magnetic substrate and including first and second transformers disposed therein, the laminate including a plurality of layers; and a second magnetic substrate provided on the laminate; wherein two ends of a primary coil of the first transformer define input and output terminals for a main signal, one end of a secondary coil of the first transformer defines a ground terminal, and the other end of the secondary coil is connected to one terminal of a secondary coil of the second transformer; one end of a primary coil of the second transformer is connected to one terminal of the first transformer, the other end of the primary coil of the second transformer is connected to the ground terminal, and one terminal of the secondary coil of the second transformer defines an output terminal for outputting a sub-signal; a winding length ratio N 1 of the secondary coil to primary coil of the first transformer and a winding length ratio N 2 of the primary coil to secondary coil of the second transformer are each set to a value that is greater than about 1 and less than or equal to about 10; and each of the primary coil and the secondary coil of the first transformer and the primary coil and the secondary coil of the second transformer includes portions disposed on at least two of the plurality of layers.