Surface-acoustic-wave device having an improved pass-band characteristic and an improved degree of freedom for setting input and output impedences

摘要

A surface-acoustic-wave device includes at least first and second surface-acoustic-wave elements (11, 21) formed on a common piezoelectric substrate (1) and cascaded with each other, each of the first and second surface-acoustic-wave elements including a plurality of interdigital electrodes (11A - 11C; 21A - 21C) having a plurality of electrode fingers overlapping with each other in correspondence to a path of a surface acoustic wave on the piezoelectric substrate, wherein the width (W 1 , W 2 ) of overlapping of the electrode fingers is changed between the first surface-acoustic-wave element and the second surface-acoustic-wave element.