Acoustic wave device and method of manufacturing the same
An acoustic wave device includes a piezoelectric substrate, a first band pass filter that is on the piezoelectric substrate and has a first pass band, and a second band pass filter that is on the piezoelectric substrate and has a second pass band at a higher frequency than the first pass band. The first and second band pass filters include resonators that include respective IDT electrodes. When a first total average metallization ratio is defined as an average of metallization ratios of all of the IDT electrodes included in the first filter and a second total average metallization ratio is defined as an average of metallization ratios of all of the IDT electrodes included in the second filter, the first total average metallization ratio is greater than the second total average metallization ratio.
1. An acoustic wave device comprising:
a substrate having piezoelectricity;
a first band pass filter that is provided on the substrate having piezoelectricity and has a first pass band; and
a second band pass filter that is provided on the substrate having piezoelectricity and has a second pass band at a higher frequency than the first pass band; wherein
the first band pass filter includes a plurality of resonators each including at least one interdigital transducer (IDT) electrode and the second band pass filter includes a plurality of resonators each including at least one IDT electrode; and
a resonator having a greatest average metallization ratio of the at least one IDT electrode thereof among the resonators included in the first band pass filter and the second band pass filter is a longest resonator in the first band pass filter in a propagation direction of acoustic wave, the average metallization ratio of the longest resonator being greater than the average metallization ratio of each resonator in the first band pass filter and the second band pass filter.
2. The acoustic wave device according to claim 1 , wherein the first band pass filter and the second band pass filter are provided on a same side surface of a piezoelectric substrate.
3. The acoustic wave device according to claim 2 , wherein components defining the first band pass filter and the second band pass filter are surrounded by a support member provided on the same side surface of the piezoelectric substrate.
4. The acoustic wave device according to claim 3 , wherein the components defining the first band pass filter and the second band pass filter are housed in a cavity defined between the support member, the piezoelectric substrate, and a cover member provided on the support member.
5. The acoustic wave device according to claim 1 , further comprising:
an antenna terminal electrically connected to an antenna; wherein
the first band pass filter and the second band pass filter are both directly commonly connected to the antenna terminal.
6. The acoustic wave device according to claim 5 , further comprising:
a first signal terminal; and
a second signal terminal; wherein
the first band pass filter is electrically connected in series between the first signal terminal and the antenna terminal; and
the second band pass filter is electrically connected in series between the second signal terminal and the antenna terminal.
7. The acoustic wave device according to claim 1 , wherein the plurality of resonators of the first band pass filter includes a plurality of series acoustic wave resonators connected in series with one another and at least one parallel acoustic wave resonator connected between a ground potential and a node between ones of the plurality of series acoustic wave resonators.
8. The acoustic wave device according to claim 7 , wherein the plurality of resonators of the second band pass filter includes a single series acoustic wave resonator and a single parallel acoustic wave resonator that is connected between a ground potential and a node connected to the single series acoustic wave resonator.
9. The acoustic wave device according to claim 1 , wherein the second band pass filter includes a resonator having a smallest average metallization ratio of the at least one IDT electrode thereof among the resonators included in the first filter and the second filter.
10. The acoustic wave device according to claim 1 , wherein a frequency difference between a higher end of the first pass band and a lower end of the second pass band is larger than or equal to a narrower one of a band width of the first pass band and a band width of the second pass band.
11. The acoustic wave device according to claim 1 , wherein the first pass band and the second pass band are pass bands for different communication bands.
12. The acoustic wave device according to claim 1 , wherein the acoustic wave device is a duplexer in which the first pass band and the second pass band are pass bands for a same communication band.
13. The acoustic wave device according to claim 1 , wherein the at least one IDT electrode included in the first band pass filter has a film thickness the same or substantially the same as that of the at least one IDT electrode included in the second band pass filter.
14. The acoustic wave device according to claim 1 , further comprising:
a plurality of bumps to be used in mounting the acoustic wave device; wherein
the plurality of bumps are disposed in line symmetry with respect to at least one of a center line of the acoustic wave device extending in a propagation direction of acoustic wave and a center line thereof extending in a direction orthogonally or substantially orthogonally intersecting the propagation direction of acoustic wave.
15. The acoustic wave device according to claim 1 , wherein the first pass band covers a range from about 791 MHz or more and about 821 MHz or less, and the second pass band covers a range from about 925 MHz or more and about 960 MHz or less.