Weighted transducer for surface acoustic wave filter

A weighted transducer for a surface acoustic wave filter, comprising:

• first overlap transducer fingers formed lengthwise on a surface of a piezoelectric substrate and having overlap widths which are continuously changed in a propagation direction of a surface acoustic wave;
• and
• second overlap transducer fingers which are formed lengthwise and alternatively arranged adjacent to said first overlap transducer fingers in a longitudinal direction of said first overlap transducer fingers, said second overlapped fingers being formed on the surface of said piezoelectric substrate and being electrically connected to each other in parallel and reverse-biased, overlapped widths of said second overlap transducer fingers being continuously changed in the propagation direction of the surface acoustic wave,
• said first and second overlap transducer being in the same relative positions to transmit a surface acoustic wave in a direction which is perpendicular to the lengthwise direction of the overlap transducer fingers,
• a sum of the overlap widths of said first and second overlap transducer fingers always being constant in the propagation direction of the surface acoustic wave.