Surface-acoustic-wave filter having an improved suppression outside a pass-band
AssigneeFujitsu Limited
InventorsOsamu Kawachi, Masanori Ueda, Akira Suga
Life of this patent
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Abstract
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.
Claims28
A SAW-filter device, comprising:
- a piezoelectric substrate;
- a double-mode SAW-filter circuit formed on said piezoelectric substrate;
- said double-mode SAW-filter circuit provided on said piezoelectric substrate;
- a package body including therein a space, said package body accommodating said piezoelectric substrate in said space together with said double-mode SAW-filter circuit, said package body carrying an input and an output pad, said package body further carrying a plurality of ground pads separated from each other, said plurality of ground pads including a first ground pad and a second ground pad, said piezoelectric substrate being mounted upon said package body in a face-down state;
- and
- a conductor cap member provided on said package body so as to close said space,
- said cap member being electrically connected to one of said first and second ground pads.
A SAW-filter device, comprising:
- a piezoelectric substrate;
- a double-mode SAW-filter circuit formed on said piezoelectric substrate, said double-mode SAW-filter circuit including a plurality of interdigital electrode pairs and outermost reflection electrodes provided on said piezoelectric substrate;
- a package body including therein a space, said package body accommodating said piezoelectric substrate in said space, said package body carrying an input pad and an output pad, said package body further carrying a first ground pad and a second ground pad separated from said first ground pad, said piezoelectric substrate being mounted upon said package body in a face-down state;
- and
- a conductor cap member provided on said package body so as to close said space,
- said cap member being electrically connected to each of said first and second ground pads via first and second impedances.
A SAW-filter device, comprising:
- a piezoelectric substrate;
- a double-mode SAW-filter circuit formed on said piezoelectric substrate, said double-mode SAW-filter circuit including a plurality of interdigital electrode pairs and outermost reflection electrodes provided on said piezoelectric substrate;
- a package body including therein a space, said package body accommodating said piezoelectric substrate in said space, said package body carrying an input pad and an output pad, said package body further carrying a first ground pad and a second ground pad separated from said first ground pad, said piezoelectric substrate being mounted upon said package body in a face-down state;
- and
- a conductor cap member provided on said package body so as to close said space,
- said first and second ground pads being electrically connected to each other via an impedance.
Dependencies are inferred from the claim text.