Patent ID: 7106148

Claim:
A branching filter serving as a ladder-type filter comprising: an antenna terminal; a first filter and a second filter having a passband higher than the passband of the first filter, the first and second filters being connected to the antenna terminal; a matching circuit positioned between the antenna terminal and the second filter; and at least one series resonator included in a series arm connecting an input terminal and an output terminal; and at least one parallel resonator included in at least one parallel arm connecting the series arm and a reference potential, the resonators being included in the first filter and second filter, respectively; wherein the second filter is a ladder-type filter in which the resonance frequency of the series resonator is higher than the antiresonant frequency of the parallel resonator; the impedance of a circuit in which the matching circuit is cascade-connected to the second filter is inductive in the passband of the second filter, when seen from the antenna-terminal side; the first filter is capacitive in the passband of the second filter; and because of the capacitive impedance of the first filter, the inductive impedance of the second filter is reduced, when seen from the antenna-terminal side.