Patent ID: 8362852
Filing Date: 2013-01-29
Classification: H03H

Abstract:
1. A branching filter comprising: an antenna terminal; a transmission signal terminal; a reception signal terminal; a transmission filter element disposed between the antenna terminal and the transmission signal terminal; and a reception filter element disposed between the antenna terminal and the reception signal terminal; wherein at least one of the transmission filter element and the reception filter element includes a longitudinally coupled resonator filter element including first and second IDT electrodes arranged along a direction of propagation of an elastic wave, the first IDT electrode having a first end connected to the antenna terminal, the second IDT electrode having a first end connected to one of the transmission signal terminal and the reception signal terminal; the longitudinally coupled resonator filter element further includes an inductor connected in series between a second end of the first IDT electrode and a ground potential and arranged to provide an attenuation range in a region higher than a pass band of the at least one of the transmission filter element and the reception filter element; and the reception filter element includes the longitudinally coupled resonator filter element, and the transmission filter element includes a ladder filter element.