Surface acoustic wave filter
A surface acoustic wave and filter technology, applied in electrical components, impedance networks, etc., can solve the problems of increasing out-of-band attenuation, increasing surface acoustic wave resonators, etc., to achieve the effect of low chip size
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no. 1 example
[0037] FIG. 1 is a plan view showing the electrode structure of the SAW filter 10 on the piezoelectric substrate 11 according to the first embodiment of the present invention. The SAW filter 10 of the embodiment has the following structure. The two IDT electrodes 12, 13 are arranged so that they are adjacent to each other on the surface of the piezoelectric substrate 11 shown and on the first surface acoustic wave propagation path, thereby forming a first electrode pattern. The reflector electrodes 14 and 15 are arranged at both ends of the first electrode pattern having IDT electrodes 12 and 13.
[0038] The IDT electrode 16 is arranged on the surface of the same piezoelectric substrate 11 and on a second surface acoustic wave propagation path different from the first surface acoustic wave propagation path, and the reflector electrodes 17, 18 are arranged at both ends thereof. In the described embodiment, the IDT electrode 16 and the reflector electrodes 17, 18 on the second surf...
no. 2 example
[0047] Hereinafter, the SAW filter 30 according to the second embodiment of the present invention will be explained with reference to FIG. 2. As shown in FIG. 2, the SAW filter 30 of the embodiment is different from the SAW filter 10 of the first embodiment in the following points. That is, in the embodiment, the reflector electrode 32 is provided between the two IDT electrodes 12, 13 included in the first electrode pattern on the first surface acoustic wave propagation path.
[0048] An example of the specific structure in FIG. 2 will be explained. In the example of the specific structure explained in the first embodiment, the electrode finger pitch is 2.40 μm, and the reflector electrode 32 whose number of electrode fingers is 10 is arranged in the two IDT electrodes 12 included in the first electrode pattern. Between 13. The respective gaps formed between the reflector electrode 32 and the IDT electrodes 12 and 13 are, for example, 1.17 μm.
[0049] By providing the reflector e...
no. 3 example
[0054] 3 is a plan view showing the electrode structure of the SAW filter according to the third embodiment of the present invention. Regarding the IDT electrodes 12, 13, 16 and the reflector electrodes 14, 15, 17, 18, 32, the SAW filter 40 of the embodiment has the same structure as the SAW filter 30 of the second embodiment. However, in the embodiment, the two IDT electrodes 12 and 13 included in the first electrode pattern on the first surface acoustic wave propagation path are connected in series by the connecting wire portions 42 and 44 through the reflector electrode 32. The resonator 24 is connected between the connecting wire portion 42 and the ground wire 20, and the connecting wire portion 42 is arranged between the first electrode pattern and the second electrode pattern.
[0055] As described above, the SAW filter 40 of the embodiment connects two IDT electrodes in series through the reflector electrode 32 and the connecting wire portions 42, 44. Therefore, when connec...
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