Patent ID: 8421555

Claim:
A duplexer comprising: a receiving side filter having a longitudinal mode resonator type filter including cross finger electrodes and reflectors respectively formed on a piezoelectric substrate and an unbalanced input signal path provided on an input side of the longitudinal mode resonator type filter; a pair of balanced output ports, arranged adjacent to each other in an area separated from said longitudinal mode resonator type filter, and connected to an output side of the longitudinal mode resonator type filter, via a conductive path; a transmitting side filter provided on the piezoelectric substrate so as to be adjacent to the receiving side filter, and using an elastic wave resonator; and a shield electrode, arranged following along a peripheral direction at, from among peripheral edges of said area, a peripheral edge other than a peripheral edge where said conductive path is arranged, and wherein the shield electrode is provided to surround from among the receiving side filter and transmitting side filter only a majority of the peripheral edge of the receiving side filter, and wherein said shield electrode is such that locations facing said area are constituted by a common electrode having a same potential.