Acoustic wave resonator with multiple resonant frequencies
Aspects of this disclosure relate to an acoustic wave resonator having at least two resonant frequencies. An acoustic wave filter can include series acoustic wave resonators and shunt acoustic wave resonators together arranged to filter a radio frequency signal. A first shunt resonator of the shunt acoustic wave resonators can include an interdigital transducer electrode and have at least a first resonant frequency and a second resonant frequency. Related acoustic wave resonators, multiplexers, wireless devices, and methods are disclosed.
1. An acoustic wave resonator with a first resonant frequency and a second resonant frequency, the acoustic wave resonator comprising:
a piezoelectric layer;
a first acoustic reflector on the piezoelectric layer;
a second acoustic reflector on the piezoelectric layer; and
an interdigital transducer electrode on the piezoelectric layer and positioned between the first acoustic reflector and the second acoustic reflector, the interdigital transducer electrode including first fingers in a first region associated with the first resonant frequency and second fingers in a second region associated with the second resonant frequency, an outer finger of the first fingers being spaced apart from the first acoustic reflector by a gap, the outer finger and an adjacent finger of the first fingers having a first pitch, the second fingers having a second pitch corresponding to the second resonant frequency, and the second pitch is less than the first pitch.
2. The acoustic wave resonator of claim 1 wherein the acoustic wave resonator is configured to generate a surface acoustic wave.
3. The acoustic wave resonator of claim 1 further comprising a temperature compensation layer over the interdigital transducer electrode.
4. The acoustic wave resonator of claim 1 further comprising a support substrate, the piezoelectric layer being positioned on the support substrate.
5. The acoustic wave resonator of claim 1 wherein the second resonant frequency is between the first resonant frequency and an edge of a pass band of an acoustic wave filter that includes the acoustic wave resonator.
6. The acoustic wave resonator of claim 1 wherein the first resonant frequency and the second resonant frequency are separated by at least 5 megahertz.
7. The acoustic wave resonator of claim 1 wherein the first fingers have the first pitch in an entirety of the first region.
8. A multiplexer with filters for filtering radio frequency signals, the multiplexer comprising:
a first filter configured to filter at least a first radio frequency signal of the radio frequency signals, the first filter including an acoustic wave resonator, the acoustic wave resonator including a piezoelectric layer; a first acoustic reflector on the piezoelectric layer; a second acoustic reflector on the piezoelectric layer; and an interdigital transducer electrode on the piezoelectric layer and positioned between the first acoustic reflector and the second acoustic reflector, the interdigital transducer electrode including first fingers in a first region associated with a first resonant frequency and second fingers in a second region associated with a second resonant frequency, the first fingers having a first pitch, an outer finger of the first fingers being spaced apart from the first acoustic reflector by a gap, the outer finger and an adjacent finger of the first fingers having a first pitch, the second fingers having a second pitch corresponding to the second resonant frequency, and the second pitch is less than the first pitch; and
a second filter coupled to the first filter at a common node, the second filter configured to filter at least a second radio frequency signal of the radio frequency signals.
9. The multiplexer of claim 8 wherein the first filter includes series acoustic wave resonators and shunt acoustic wave resonators, and the shunt acoustic wave resonators include the acoustic wave resonator.
10. The multiplexer of claim 8 wherein the first filter is a band pass filter having a pass band.
11. The multiplexer of claim 10 wherein the first second resonant frequency is between the first resonant frequency and an edge of the pass band.
12. The multiplexer of claim 8 wherein the second filter includes acoustic wave resonators.
13. The multiplexer of claim 8 further comprising a third filter coupled to the common node, the third filter configured to filter at least a third radio frequency signal of the radio frequency signals.
14. The multiplexer of claim 8 wherein the multiplexer is configured to provide filtering for at least two carriers of a carrier aggregation.
15. An acoustic wave filter configured to filter a radio frequency signal, the acoustic wave filter comprising:
shunt acoustic wave resonators including a first shunt acoustic wave resonator, the first shunt acoustic wave resonator including a piezoelectric layer; a first acoustic reflector on the piezoelectric layer; a second acoustic reflector on the piezoelectric layer; and an interdigital transducer electrode on the piezoelectric layer and positioned between the first acoustic reflector and the second acoustic reflector, the interdigital transducer electrode including first fingers in a first region associated with a first resonant frequency and second fingers in a second region associated with a second resonant frequency, an outer finger of the first fingers being spaced apart from the first acoustic reflector by a gap, the outer finger and an adjacent finger of the first fingers having a first pitch, the second fingers having a second pitch corresponding to the second resonant frequency, and the second pitch is less than the first pitch; and
series acoustic wave resonators, the series acoustic wave resonators and the shunt acoustic wave resonators together arranged to filter the radio frequency signal.
16. The acoustic wave filter of claim 15 wherein the acoustic wave filter is a band pass filter having a pass band.
17. The acoustic wave filter of claim 16 wherein the second resonant frequency is between the first resonant frequency and an edge of the pass band.
18. The acoustic wave filter of claim 15 wherein the first resonant frequency and the second resonant frequency are separated by at least 5 megahertz.
19. The acoustic wave filter of claim 15 wherein the acoustic wave filter has a pass band corresponding to a fifth generation New Radio operating band.
20. The acoustic wave filter of claim 15 wherein the first shunt acoustic wave resonator is configured to generate a surface acoustic wave.