Surface acoustic wave device

摘要

The present invention provides a surface acoustic wave filter having an unbalance-to-balance conversion function and an impedance conversion function. This surface acoustic wave filter includes a piezoelectric substrate, a first surface acoustic wave filter that is made up of input and output interdigital transducers (IDTs), and a second surface acoustic wave filter that is also made up of input and output IDTs. The phase difference between the first. surface acoustic wave filter and the second surface acoustic wave filter is approximately 180°. The input IDT of the first surface acoustic wave filter is connected to the input IDT of the second surface acoustic wave filter by a connecting wire, and a terminal extending from this connecting wire serves as an unbalanced terminal. An output terminal extends from the output IDTs of the first surface acoustic wave filter that are not connected to the second surface acoustic wave filter, and another output terminal extends from the output IDTS of the second surface acoustic wave filter that are not connected to the first surface acoustic wave filter. These output terminals constitute a balanced terminal 35.