DUPLEXER

摘要

To provided a miniaturized duplexer having a good isolation characteristic. A duplexer having a high band side filter 4 and a low band side filter 3 that are each formed in a ladder-type filter provided on a common piezoelectric substrate 11 is provided with a first elastic wave resonator 31a to be included in one of these filters, a second elastic wave resonator 42c to be included in the other of the filters, and a first additional grating reflector 86a provided between these resonators 31a and 42c to reflect an elastic wave leaked from a grating reflector of the first elastic wave resonator 31a, and in which an additional grating reflector is not provided on a side opposite to the second elastic wave resonator 42c in the first elastic wave resonator 31a.