SURFACE-ACOUSTIC-WAVE FILTER, SURFACE-ACOUSTIC-WAVE FILTER DEVICE, AND DUPLEXER

摘要

This invention provides a technology whereby ripple in a surface-acoustic-wave filter using shared reflectors can be reduced. Said surface-acoustic-wave filter (1) is provided with a first vertically-coupled-resonator filter unit (4) and a second vertically-coupled-resonator filter unit (5) that is electrically connected in parallel or in series with the first vertically-coupled-resonator filter unit (4) and is provided in line with the first vertically-coupled-resonator filter unit (4) in the propagation direction of surface acoustic waves. The first vertically-coupled-resonator filter unit (4) contains a first IDT group (40) lined up in the propagation direction of the surface acoustic waves, and the second vertically-coupled-resonator filter unit (5) contains a second IDT group (50) lined up in the propagation direction of the surface acoustic waves. Reflectors (61) laid out between the first IDT group (40) and the second IDT group (50) are configured as integrated shared reflectors, and the number of reflectors (61) is odd and no less than 9.