Patent ID: 8040205

Claim:
A duplexer comprising: a substrate including an insulation layer, an upper interconnection layer provided on an upper surface of the insulation layer, a lower interconnection layer provided on a lower surface of the insulation layer, and an inner interconnection layer provided in the insulation layer, the inner interconnection layer including an inner ground pad; at least one acoustic wave filter chip mounted on an upper surface of the substrate; signal pads provided on the upper interconnection layer and connected to signal electrodes of the at least one acoustic wave filter chip; and an upper ground pad that is provided in the upper interconnection layer so as to be located between the signal pads and is connected to a ground electrode of the at least one acoustic wave filter, wherein D 1 >D 2 and D 1 >T 1 where D 1 is a minimum distance between the signal pads and the upper ground pad, D 2 is a minimum distance between the signal pads and the inner ground pad, and T 1 is a thickness of the insulation layer between the upper interconnection layer and the inner interconnection layer.