Surface-acoustic-wave filter having an improved suppression outside a pass-band

摘要

A SAW-filter device includes a piezoelectric substrate carrying thereon a first interdigital electrode pair connected to an input terminal and a second interdigital electrode pair connected to an output terminal. The first interdigital electrode pair is grounded to a first ground pad, while the second interdigital electrode pair is grounded to a second ground pad different from the first ground pad. The piezoelectric substrate is accommodated into a space formed in a package body, wherein the space is covered by a metal cap member connected to one of the first and second ground pads.