| 摘要 |
<p>A surface acoustic wave filter unit (202) having three interdigital transducers (206,207,208) along the surface acoustic wave propagation direction is formed on a piezoelectric substrate (201) so as to provide a balance-to-unbalance conversion function. Balanced signal terminals (214,215) are connected to a pair of electrode finger sets of the centre interdigital transducer (207). An unbalanced signal terminal (213) is connected to one electrode finger set of each of the end interdigital transducers (206,208). The other electrode finger set of each of the end interdigital transducers (206,208) is connected to a ground terminal (216,218). The ground terminals (216,218) connected to the end interdigital transducers (206,208) are electrically isolated from each other on the piezoelectric substrate (201).</p> |
