Acoustic wave filter with overtone mode resonators
Aspects of this disclosure relate to acoustic wave filters with bulk acoustic wave resonators configured to excite an overtone mode as a main mode. A bulk acoustic wave resonator of the filter can include a plurality of stacked piezoelectric layers positioned between a pair of electrodes.
1. An acoustic wave filter with overtone mode bulk acoustic wave resonators, the acoustic wave filter comprising:
a first bulk acoustic wave resonator including a first plurality of stacked piezoelectric layers positioned between a pair of first electrodes, the first bulk acoustic wave resonator configured to excite an overtone mode as a main mode of the first bulk acoustic wave resonator; and
a second bulk acoustic wave resonator including a second plurality of stacked piezoelectric layers positioned between a pair of second electrodes, the second bulk acoustic wave resonator configured to excite the overtone mode as a main mode of the second bulk acoustic wave resonator, the second bulk acoustic wave resonator coupled to the first bulk acoustic wave resonator, and the acoustic wave filter configured to filter a radio frequency signal.
2. The acoustic wave filter of claim 1 wherein all bulk acoustic wave resonators of the acoustic wave filter are configured to excite the overtone mode as a respective main mode.
3. The acoustic wave filter of claim 1 wherein the first and second bulk acoustic wave resonators are on a common substrate, the first and second bulk acoustic wave resonators are enclosed within a packaging structure, and the packaging structure includes a cap wafer positioned over the first and second bulk acoustic wave resonators.
4. The acoustic wave filter of claim 1 further comprising a third bulk acoustic wave resonator, the first and second bulk acoustic wave resonators being on a side of a first substrate, the third bulk acoustic wave resonator being on a side of a second substrate, the side of the first substrate facing the side of the second substrate, and the first, second, and third bulk acoustic wave resonators being co-packaged with each other.
5. The acoustic wave filter of claim 4 wherein the third bulk acoustic wave resonator includes a single piezoelectric layer.
6. The acoustic wave filter of claim 4 wherein the third bulk acoustic wave resonator is electrically connected to the first bulk acoustic wave resonator by way of a conductive pillar.
7. The acoustic wave filter of claim 1 further comprising an integrated passive device inductor co-packaged with the first and second bulk acoustic wave resonators, the integrated passive device inductor being electrically connected to the first bulk acoustic wave resonator.
8. The acoustic wave filter of claim 1 further comprising an integrated passive device capacitor co-packaged with the first and second bulk acoustic wave resonators, the integrated passive device capacitor being electrically connected to the first bulk acoustic wave resonator.
9. The acoustic wave filter of claim 1 wherein the first plurality of stacked piezoelectric layers includes first piezoelectric layer having a first c-axis and a second piezoelectric layer having a second c-axis, and the first c-axis and the second c-axis are oriented in substantially opposite directions.
10. The acoustic wave filter of claim 1 wherein the first plurality of stacked piezoelectric layers have a combined thickness in a range from 0.2 micrometer to 5 micrometers.
11. The acoustic wave filter of claim 1 wherein the first bulk acoustic wave resonator includes a raised frame structure.
12. The acoustic wave filter of claim 11 wherein the first bulk acoustic wave resonator includes a recessed frame structure.
13. The acoustic wave filter of claim 1 wherein a resonant frequency of the overtone mode of the first bulk acoustic wave resonator is in a range from 5 gigahertz to 12 gigahertz.
14. The acoustic wave filter of claim 1 wherein the acoustic wave filter is a band pass filter having a passband corresponding to a fifth generation New Radio operating band.
15. The acoustic wave filter of claim 1 wherein the overtone mode is a second overtone mode.
16. The acoustic wave filter of claim 1 wherein the overtone mode is a third overtone mode.
17. The acoustic wave filter of claim 1 wherein the first bulk acoustic wave resonator includes an air cavity over a substrate.
18. The acoustic wave filter of claim 1 wherein the acoustic wave filter is a transmit filter.
19. A radio frequency module comprising: the acoustic wave filter of claim 1 ; and
a radio frequency circuit element coupled to the acoustic wave filter, the acoustic wave filter and the radio frequency circuit element being enclosed within a common package.
20. A wireless communication device comprising:
the acoustic wave filter of claim 1 ;
an antenna operatively coupled to the acoustic wave filter;
a radio frequency amplifier operatively coupled to the acoustic wave filter and configured to amplify a radio frequency signal; and
a transceiver in communication with the radio frequency amplifier.