SURFACE ACOUSTIC WAVE DEVICE HAVING EXCELLENT VSWR AND EXHIBITING DESIRED IMPEDANCE RATIO OF INPUT TERMINAL TO OUTPUT TERMINAL AND COMMUNICATION APPARATUS HAVING THE SAME

摘要

PURPOSE: A surface acoustic wave device having an excellent VSWR(Voltage Standing Wave Ratio) and exhibiting a desired impedance ratio of an input terminal to an output terminal and a communication apparatus having the same are provided to set a desired impedance ratio between an input terminal and an output terminal. CONSTITUTION: A surface acoustic wave device includes a first longitudinally coupled resonator type surface acoustic wave element(501,503) and a second longitudinally coupled resonator type surface acoustic wave element(502,504). The first longitudinally coupled resonator type surface acoustic wave element and the second longitudinally coupled resonator type surface acoustic wave element are cascaded to each other and are arranged on a piezoelectric substrate. At least one of interdigital transducers of each of the first and second longitudinally coupled resonator type surface acoustic wave elements has a narrow pitch electrode finger part located near the adjacent interdigital transducer. At least one of the number and the pitch of the electrode fingers of the narrow pitch electrode finger parts of the first longitudinally coupled resonator type surface acoustic wave element are different from that of the electrode fingers of the narrow pitch electrode finger parts of the second longitudinally coupled resonator type surface acoustic wave element.