| 摘要 |
PURPOSE: A balance type surface acoustic wave filter is provided to convert an unbalanced signal to a balanced signal by using an input interdigital transducer and an output interdigital transducer. CONSTITUTION: A balance type surface acoustic wave filter includes the first filter portion(10) and the second filter portion(20). The first filter portion is formed with a plurality of surface acoustic wave filters(11,12) including input interdigital transducers(11a,12a,12b) and output interdigital transducers(11b,11c,12c) in order to filter an input signal and output the filtered signal. The second filter portion is formed with a plurality of surface acoustic wave filters(21,22) including input interdigital transducers(21a,22a,22b) and output interdigital transducers(21b,21c,22c). The surface acoustic wave filters of the second filter portion are arranged inversely to the surface acoustic wave filters of the first filter portion in order to output a signal having a different phase of 180 degrees from the phase of an output signal of the first filter portion. |
