Patent Number: 6,310,422

Title: Surface acoustic wave filter

Abstract: The present invention relates to a surface acoustic wave filter used in frequency filter of portable telephone and other mobile communication device, and is intended to realize a surface acoustic wave filter capable of obtaining a stable filter characteristic even in the event of input of a large signal. The invention includes resonators (5) to (8) formed on a piezoelectric substrate (3), through-holes (12) provided near the resonators (5) to (8), and a conductive material (13) filling up the through-holes (12), in which the through-holes (12) filled up with the conductive material (13) are electrically grounded. In this constitution, by the through-holes (12) provided near the resonators (5) to (8) and filled up with the conductive material (13), the heat generated in the resonators (5) to (8) when a large signal is applied to the input terminal (1) can be released, so that a stable filter characteristic may be maintained if a large signal is applied.

Inventors: Satoh; Yuki (Osaka, JP), Sakuragawa; Toru (Osaka, JP), Furukawa; Mitsuhiro (Osaka, JP), Takayama; Ryouichi (Osaka, JP)

Assignee: Matsushita Electric Industrial Co., Ltd.

International Classification: H03H 9/05 (20060101); H03H 9/00 (20060101); H03H 9/08 (20060101); H03H 9/64 (20060101); H03H 009/25 ()

Expiration Date: 10/30/2018