Abstract: The branching filter has the piezoelectric substrate having the main surface on which there are formed a transmission filter, which includes an input electrode and an antenna electrode, and a reception filter, which includes an output electrodes and the antenna electrode. The branching filter also has the mounting substrate having, on a first main surface, a first electrode group that is connected to the transmission filter and reception filter and that is formed symmetrical with respect to a line when viewed from the above, and also having, on a second main surface locating on the opposite side to the first main surface, a second electrode group that is connected to the circuit interconnects of an external circuit board and that is formed symmetrical with respect to a line when viewed from the above.

Abstract: To provide a branching filter enabling sharing of the same mounting substrate between the normal arrangement and the mirror arrangement that is symmetric to the normal arrangement of an electrode group formed on a main surface of a piezoelectric substrate and a method for manufacturing the same. The branching filter 1 has the piezoelectric substrate 20 having the main surface on which there are formed a transmission filter 26, which includes an input electrode 22 and an antenna electrode 23, and a reception filter 27, which includes an output electrodes 24, 25 and the antenna electrode 23.

Abstract: A duplexer includes a piezoelectric substrate, a transmitting filter, and a receiving filter. A transmitting filter includes a ladder filter having a first resonator group which has one or more resonators in one or more series arms and one or more resonators in one or more parallel arms. A receiving filter has a passband higher than that of the transmitting filter, and includes a second resonator group which has one or more resonators in one or more series arms and one or more resonators in one or more parallel arms. A node connects both the transmitting filter and the receiving filter. The receive-side closest resonator closest to the node in the parallel arm is closer to the node than a resonator which is closest to the node in the series arm, and a resonance frequency of the receive-side closest resonator is lower than the passband of the transmitting filter.

Abstract: A filter device includes a circuit board having a pattern electrode; a substrate having a filter to which a signal line for inputting or outputting a signal and a reference potential line having a reference potential are connected, and a pad electrode connected to the filter, the substrate being mounted on the circuit board such that the pad electrode and the pattern electrode face each other; and a connection part formed of the pad electrode, the pattern electrode, and a conductive member formed between the pattern electrode and the pad electrode to electrically connect the pattern electrode to the pad electrode, wherein the connection part is arranged to connect the signal line to the reference potential line.

Abstract: A duplexer includes a piezoelectric substrate, a transmitting filter, and a receiving filter. A transmitting filter includes a ladder filter having a first resonator group which has one or more resonators in one or more series arms and one or more resonators in one or more parallel arms. A receiving filter has a passband higher than that of the transmitting filter, and includes a second resonator group which has one or more resonators in one or more series arms and one or more resonators in one or more parallel arms. A node connects both the transmitting filter and the receiving filter. The receive-side closest resonator closest to the node in the parallel arm is closer to the node than a resonator which is closest to the node in the series arm, and a resonance frequency of the receive-side closest resonator is lower than the passband of the transmission filter.

Abstract: A filter device includes a circuit board having a pattern electrode; a substrate having a filter to which a signal line for inputting or outputting a signal and a reference potential line having a reference potential are connected, and a pad electrode connected to the filter, the substrate being mounted on the circuit board such that the pad electrode and the pattern electrode face each other; and a connection part formed of the pad electrode, the pattern electrode, and a conductive member formed between the pattern electrode and the pad electrode to electrically connect the pattern electrode to the pad electrode, wherein the connection part is arranged to connect the signal line to the reference potential line.