Patent ID: 8283997
Filing Date: 2012-10-09
Classification: H03H

Abstract:
1. An elastic-wave filter device comprising: a longitudinally coupled resonator-type elastic-wave filter including an input pad, two output pads, and at least one ground pad; and a package substrate on which the longitudinally coupled resonator-type elastic-wave filter is mounted and including an insulation substrate body, a conductive filter mounting pattern provided on a first main surface of the substrate body, a conductive back-side terminal pattern provided on a second main surface of the substrate body, a conductive internal electrode pattern provided inside the substrate body, a plurality of first via conductors extending inside the substrate body and electrically connecting the filter mounting pattern and the internal electrode pattern, and a plurality of second via conductors extending inside the substrate body and electrically connecting the internal electrode pattern and the back-side terminal pattern; wherein the filter mounting pattern includes an input pattern element connected to the input pad of the longitudinally coupled resonator-type elastic-wave filter, two output pattern elements connected to the two output pads of the longitudinally coupled resonator-type elastic-wave filter, respectively, and a ground pattern element connected to the ground pad of the longitudinally coupled resonator-type elastic-wave filter; the internal electrode pattern includes an internal ground pattern element connected to the ground pattern element of the filter mounting pattern through the plurality of first via conductors disposed therebetween; the plurality of first via conductors electrically connecting the ground pattern element of the filter mounting pattern and the internal ground pattern element of the internal electrode pattern are arranged asymmetrically with respect to a center line extending parallel to a side edge of the package substrate, passing through a bump disposed on the input pattern element of the filter mounting pattern, and passing between the two output pattern elements of the filter mounting pattern; for the plurality of first via conductors electrically connecting the ground pattern element of the filter mounting pattern and the internal ground pattern element of the internal electrode pattern, a number of the plurality of first via conductors arranged at a first side with respect to the center line is different from a number of the plurality of first via conductors arranged at a second side with respect to the center line; of the plurality of first via conductors, a first via conductor connected to a first output pattern element of the two output pattern elements of the filter mounting pattern is arranged at a first side with respect to the center line and a first via conductor connected to a second output pattern element of the two output pattern elements of the filter mounting pattern is arranged at a second side with respect to the center line; a distance between the first via conductor connected to the first output pattern element of the filter mounting pattern arranged at the first side and the center line is greater than a distance between the first via conductor connected to the second output pattern element of the filter mounting pattern arranged at the second side and the center line; and for the plurality of first via conductors electrically connecting the ground pattern element of the filter mounting pattern and the internal ground pattern element of the internal electrode pattern, a number of the plurality of first via conductors arranged at the first side with respect to the center line is greater than a number of the plurality of first via conductors arranged at the second side with respect to the center line.