| 摘要 |
A surface acoustic wave filter includes a piezoelectric substrate and a plurality of surface acoustic wave resonators provided on the piezoelectric substrate and connected to define a ladder filter circuit. The filter circuit includes input-side balanced signal terminals A1 and A2 connected to an external balanced circuit, output-side balanced signal terminals B1 and B2 connected to an external balanced circuit, at least one first series arm surface acoustic wave resonator connected in series between the input-side balanced signal terminal A1 and the output-side balanced signal terminal B1, at least one second series arm surface acoustic wave resonator connected in series between the input-side balanced signal terminal A2 and the output-side balanced signal terminal B2, and at least one impedance element connected between a first signal line connecting the input-side balanced signal terminal A1 to the output-side balanced signal terminal B1 and a second signal line connecting the input-side balanced signal terminal A2 to the output-side balanced signal terminal B2.
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