Patent ID: 7579927

Claim:
A duplexer comprising: a transmission filter and a reception filter that have different band center frequencies from each other; a phase matching circuit that performs phase matching on the transmission filter and the reception filter; and a laminated package that includes a first layer, a second layer, a first ground foot pad used for external connection, a second ground foot pad used for external connection, a transmission signal foot pad used for external connection and a reception signal foot pad used for external connection, the transmission filter, the reception filter, and the phase matching circuit being mounted on the first layer; the first layer comprising a first ground line pattern that is connected to a ground of the transmission filter, a second ground line pattern that is connected to a ground of the reception filter, a third ground line pattern that is connected to a ground of the phase matching circuit, a first transmission signal line pattern, and a first reception signal line pattern, the second layer being located below the first layer, the second layer comprising a second transmission signal line pattern that is connected to the transmission filter via the first transmission signal line pattern and is connected to the transmission signal foot pad, a second reception signal line pattern that is connected to the reception filter via the first reception signal line pattern and is connected to the reception signal foot pad, and a partition ground line pattern that is located between the second transmission signal line pattern and the second reception signal line pattern in the same surface of the second layer, the first ground line pattern being connected to the partition ground line pattern only via the first ground foot pad, and the second ground line pattern being connected to the partition ground line pattern only via the second ground foot pad.