Surface acoustic wave filter

摘要

A surface acoustic wave filter includes a first acoustic channel which has first input/output transducers and which is configured so as to define a first transfer function by the first input/output transducers, and a second acoustic channel which has second input/output transducers and which is configured so as to define a second transfer function by the second input/output transducers. The first and second acoustic channels are electrically connected in parallel. The first and second transfer functions are substantially in phase within a pass band, while they have substantially opposite phases outside the pass band. The bandwidth of the second acoustic channel is narrower than that of the first acoustic channel. A first side lobe of the second transfer function has a phase opposite to that of a main lobe of the first acoustic channel.