Surface acoustic wave apparatus and communications unit

摘要

Three longitudinal-coupling-resonator-type interdigital transducers (IDTs) (1-3) having a balanced-to-unbalanced conversion function are disposed on a piezoelectric substrate (8) in a direction in which a surface acoustic wave (SAW) propagates. Weighting is applied to at least one (2/3) of the IDTs. For example, among the electrode fingers of the IDT (2) located on the left side, an apodization-weighted electrode finger (22a) is provided for one of the electrode fingers positioned adjacent to the central IDT (1).