Patent ID: 6150904
Filing Date: 2000-11-21
Classification: H03H

Abstract:
A surface acoustic wave filter comprising:a piezoelectric substrate;a surface acoustic wave filter element including series arm resonators and parallel arm resonators arranged on said piezoelectric substrate so as to define a ladder-type circuit which has a series arm having input and output terminals and a plurality of parallel arms located between the series arm and a reference potential;a package for holding the surface acoustic wave filter element therein and having a plurality of electrode lands electrically connected to the surface acoustic wave filter element; anda plurality of connecting members by which the input and output terminals and a reference potential terminal of the surface acoustic wave filter element are electrically connected to the plurality of electrode lands of the package, respectively; whereina first one of the parallel arm resonators is connected between the reference potential and a connection point between the input terminal and one of the series arm resonators which is closest to the input terminal, and a second one of the parallel arm resonators is connected between the reference potential and a connection point between the output terminal and one of the series arm resonators which is closest to the output terminal, andwherein reference potential electrodes of the first and second parallel arm resonators are connected to first and second of the electrode lands which are disposed in the package and which are electrically insulated from each other, respectively, and a reference potential electrode of another one of the parallel arm resonators is short-circuited with the reference potential electrode of the first or second parallel arm resonator within the package.