Patent ID: 8319585

Claim:
An elastic wave filter device comprising: an elastic wave filter including an input-side resonator coupled to an output-side resonator, the input-side resonator being connected between an input line and at least one first ground line, the output-side resonator being connected between an output line and at least one second ground line; a parallel trap connected between at least one third ground line and the input line or the output line; and a piezoelectric substrate including the elastic wave filter and the parallel trap provided thereon; wherein the elastic wave filter device includes: a first ground connection electrode that is provided on a surface of the piezoelectric substrate and that is connected to the at least one first ground line and the at least one second ground line; and a second ground connection electrode that is provided on the surface of the piezoelectric substrate so as to be isolated from the first ground connection electrode and that is connected to the at least one third ground line; the parallel trap is defined by a resonator including a pair of comb-shaped electrodes; one of the pair of comb-shaped electrodes is connected to the input line or the output line and the other one of the pair of the comb-shaped electrodes is connected to the at least one third ground line; and the first ground connection electrode is disposed along a first side of the piezoelectric substrate and the second ground connection electrode is disposed along a second side of the piezoelectric substrate opposite to the first side of the piezoelectric substrate.