Surface acoustic wave filter and communication apparatus

摘要

A surface acoustic wave filter unit includes three interdigital transducers arranged along the surface acoustic wave propagation direction on a piezoelectric substrate so as to provide a balance-to-unbalance conversion function. Balanced signal terminals are connected to a pair of electrode finger sets of the center interdigital transducer. An unbalanced signal terminal is connected to one electrode finger set of each of the end interdigital transducers. The other electrode finger set of each of the end interdigital transducers is connected to a ground terminal. The ground terminals connected to the end interdigital transducers are electrically isolated from each other on the piezoelectric substrate.