US 2001/0011934 A1Published application

Ladder filter

AssigneeMurata Manufacturing Co., Ltd.

InventorTakashi Yamamoto

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Abstract

A very small size ladder filter has various numbers defining different stages. The ladder filter includes units each defined by stacking a top surface surface-electrode of a bending resonator defining a serial resonator and the bottom surface surface-electrode of a bending resonator defining a parallel resonator with a metallic terminal plate sandwiched therebetween. Two of these units are two-dimensionally arranged on a substrate, and a metallic lid is put on the substrate so as to cover the units. The bottom surface surface-electrode of the serial resonator in a first-stage unit is connected to an input terminal, then the metallic terminal plate in the first stage unit is connected to the bottom surface surface-electrode of the serial resonator in the next-stage unit, and the metallic terminal plate in the next-stage unit is connected to an output terminal. The top-surface surface electrodes of the parallel resonators of all of the units are made conductive to one another by the lid.

Claims19

Dependent claims

A ladder filter comprising:

a substrate;
a plurality of conductive members;
a plurality of sets of units each of which includes a serial resonator utilizing area bending vibration and having one side surface electrode provided thereon, and a parallel resonator utilizing area bending vibration and having one side surface electrode provided thereon stacked on said serial resonator with at least one of said plurality of conductive members sandwiched between said one side surface electrode of said serial resonator and said one side surface electrode of said parallel resonator;
conductive patterns provided on said substrate;
and
a conductive lid for covering said plurality of sets of units;
wherein
the plurality of sets of said units are two-dimensionally arranged on said substrate;
said lid is provided on said substrate so as to cover said plurality of sets of units;
another of side surface electrodes of said serial resonator in each of said plurality of sets of units at a second stage and at stages thereafter is conductive with said conductive member at the preceding stage by said conductive patterns and said lid;
and
another of said side surface electrodes of said parallel resonators of all of the units are conductive with one another.

9 more elements

Dependencies are inferred from the claim text.