Surface acoustic wave filter, branching filter, and communications apparatus

摘要

A surface acoustic wave filter includes a piezoelectric substrate (110) and a plurality of one-terminal-pair surface acoustic wave resonators (111,112), which are disposed on the piezoelectric substrate in a ladder pattern and each of which includes an IDT electrode having a pair of comb electrodes. The one-terminal-pair surface acoustic wave resonators disposed in a ladder pattern include series resonators (111a-c), all of which are thinned-out. The electrode pitch of the IDT electrode of at least one (111b) of the series resonators is different from that of the IDT electrodes of the other series resonators (111a,c).