Elastic wave filter device and antenna duplexer using same

摘要

An elastic wave filter device includes a longitudinally coupled resonator-type elastic wave filter formed on a piezoelectric substrate; and a ladder-type elastic wave filter connected to the resonator-type elastic wave filter. The resonator-type filter includes an input IDT and an output IDT. The ladder-type filter includes a series arm resonator and a parallel arm resonator. A first ground electrode connected to the parallel arm resonator is electrically separated from a second ground electrode connected to at least one of the input IDT and the output IDT.

主权项

1. An elastic wave filter device comprising:
a longitudinally coupled resonator-type elastic wave filter formed on a piezoelectric substrate and including an input IDT and an output IDT; a ladder-type elastic wave filter formed on the piezoelectric substrate and connected to the longitudinally coupled resonator-type elastic wave filter, the ladder-type elastic wave filter including a plurality of series arm resonators and a plurality of parallel arm resonators; a first ground electrode connected to each of the parallel arm resonators and to one of the input IDT and the output IDT; and a second ground electrode connected to the other of the input IDT and the output IDT, the first ground electrode being electrically separated from the second ground electrode.