Surface acoustic wave filter and multistage surface acoustic wave filter

摘要

A surface acoustic wave resonator is constituted by an IDT electrode and reflector electrodes disposed on both sides thereof, on a piezoelectric substrate. Two of said surface acoustic wave resonators are disposed nearby so that the propagation directions of the respective surface acoustic waves are in parallel to each other to make acoustic couple to constitute a surface acoustic wave filter having plural exciting modes with different propagation frequencies. The bus bar electrodes of each of two IDT electrodes are electrically separated from each other, and the leading out electrodes led out from at least two spots on those bus bar electrodes are electrically connected to each other, by which one side of the balanced input and output terminal. As a result, the electrode resistance of the IDT electrode is alleviated to make the insertion loss less.