Surface acoustic-wave resonator filter having shifted resonant frequencies

摘要

A surface acoustic-wave resonator filter having improved group delay time characteristics. The filter comprises three energy-confined acoustic-wave resonator filter sections formed on a piezoelectric substrate. The second resonator filter section is positioned between the first and third resonator filter sections. One frequency in a vertical higher-order mode of the second filter section is placed on the lower-frequency side of one frequency in a vertical higher-order mode of the first and third filter sections. Or, one frequency in a vertical lower-order mode of the second filter section is placed on the higher-frequency side of one frequency in a vertical lower-order mode of the first and third filter sections.