Elastic wave filter, and duplexer and electronic device using same

摘要

An elastic wave filter includes first and second longitudinally coupled elastic wave filters. The first filter includes a first pair of grating reflectors, first to fifth IDT electrodes arranged in ordinal order between the grating reflectors along a propagation direction of elastic waves, a first unbalanced terminal, and first and second balanced terminals. The second filter has a second unbalanced terminal, and third and fourth balanced terminals, the first and second unbalanced terminals being electrically connected to each other, the first and third balanced terminals being electrically connected to a first JO terminal, and the second and fourth balanced terminals being electrically connected to a second JO terminal. The first and second balanced terminals, and the third and fourth balanced terminals, output signals opposite in phase to each other. A first signal at the first JO terminal is opposite in phase to a second signal at the second IO terminal.

主权项

1. An elastic wave filter comprising:
a first longitudinally coupled elastic wave filter having a first unbalanced signal terminal, a first balanced signal terminal, and a second balanced signal terminal, the first longitudinally coupled elastic wave filter including a first pair of grating reflectors, first, second, third, fourth, and fifth IDT electrodes arranged in ordinal order between the grating reflectors of the first pair of grating reflectors along a propagation direction of elastic waves in the first longitudinally coupled elastic wave filter; and a second longitudinally coupled elastic wave filter having a second unbalanced signal terminal, a third balanced signal terminal, and a fourth balanced signal terminal, the first and second unbalanced signal terminals being electrically connected to each other, the first and third balanced signal terminals being electrically connected to a first input/output terminal, and the second and fourth balanced signal terminals being electrically connected to a second input/output terminal, the first and second balanced signal terminals outputting signals opposite in phase to each other, the third and fourth balanced signal terminals outputting signals opposite in phase to each other, and a first signal at the first input/output terminal being opposite in phase to a second signal at the second input/output terminal.