Transversal type filter

A transversal type filter comprising:

• an input IDT provided with a large number of finger electrodes;
• an output IDT provided with a large number of finger electrodes to receive an elastic wave propagated from the input IDT, wherein the finger electrodes of at least either of the input IDT and the output IDT are weighted so that a magnitude of amplitude of the elastic wave excited or received between the finger electrodes is changed between the respective finger electrodes;
• an apodized region provided in at least either of the input IDT and the output IDT and in which a weighting is performed on a aperture of the finger electrodes using an apodizing method;
• and
• a dog-leg region provided in at least either of the input IDT and the output IDT, formed on at least either of regions adjacent to said apodized region in a propagation direction of the elastic wave, and formed by dividing a propagation region of the elastic wave into a plurality of propagation paths in parallel with the propagation direction of the elastic wave using a dog-leg method;
• wherein an apodized composite region in which the aperture of the finger electrodes is weighted by the apodizing method is formed on each of the plurality of propagation paths;
• wherein said apodized region includes at least two finger electrodes whose aperture is adjusted so that a weighting amount of the finger electrodes takes a maximum value in at least either of the input IDT and the output IDT on which the weighting is performed by the apodizing method;
• and
• wherein a withdrawn composite region in which a propagation region of the elastic wave is divided into a plurality of propagation paths in parallel with the propagation direction of the elastic wave using the dog-leg method and a crossing position of the finger electrodes is withdrawn in each of the propagation paths using the withdrawal method, is connected to a region in said dog-leg region on the opposite side of said apodized region.

A transversal type filter comprising:

• an input IDT provided with a large number of finger electrodes;
• an output IDT provided with a large number of finger electrodes to receive an elastic wave propagated from the input IDT, wherein the finger electrodes of at least either of the input IDT and the output IDT are weighted so that a magnitude of amplitude of the elastic wave excited or received between the finger electrodes is changed between the respective finger electrodes;
• an apodized region provided in at least either of the input IDT and the output IDT and in which a weighting is performed on a aperture of the finger electrodes using an apodizing method;
• and
• a dog-leg region provided in at least either of the input IDT and the output IDT, formed on at least either of regions adjacent to said apodized region in a propagation direction of the elastic wave, and formed by dividing a propagation region of the elastic wave into a plurality of propagation paths in parallel with the propagation direction of the elastic wave using a dog-leg method;
• wherein an apodized composite region in which the aperture of the finger electrodes is weighted by the apodizing method is formed on each of the plurality of propagation paths;
• wherein said apodized region includes at least two finger electrodes whose aperture is adjusted so that a weighting amount of the finger electrodes takes a maximum value in at least either of the input IDT and the output IDT on which the weighting is performed by the apodizing method;
• and
• wherein a region in which the weighting amount of the finger electrodes is zero is interposed on a boundary between said apodized region and said dog-leg region and within said dog-leg region between the apodized composite region and a withdrawn composite region in which the number of propagation paths divided by the dog-leg method is different.