Temperature compensated bulk acoustic wave devices using over-moded acoustic reflector layers
View Patent ↗Embodiments of apparatuses, systems and methods relating to temperature compensated bulk acoustic wave devices. In some embodiments, temperature compensated bulk acoustic wave devices are described with an over-moded reflector layer.
1. A bulk acoustic wave (BAW) device comprising:
a first electrode;
a second electrode;
a piezoelectric layer coupled with and between the first and second electrodes; and
a reflector stack coupled with the second electrode and having a reflector layer to provide temperature compensation, the reflector layer having a thickness that is between approximately ¾ acoustic longitudinal wavelength and ⅘ of the acoustic longitudinal wavelength at a frequency of a main resonance of the BAW device.
2. The BAW device of claim 1 , wherein the reflector layer comprises a silicon dioxide layer.
3. The BAW device of claim 2 , wherein the BAW device is a solidly mounted resonator (SMR) and the reflector layer includes alternating silicon dioxide and tungsten layers.
4. The BAW device of claim 3 , wherein the reflector layer is a topmost layer of the reflector stack.
5. A bulk acoustic wave (BAW) device comprising:
a first electrode;
a second electrode;
a piezoelectric layer coupled with and between the first and second electrodes; and a reflector stack coupled with the second electrode and having a reflector layer to provide temperature compensation, the reflector layer having a thickness that is at least half of an acoustic longitudinal wavelength at a frequency of a main resonance of the BAW device, wherein the reflector layer is configured to include approximately 30% of an energy of an acoustic wave in the BAW device.
6. A bulk acoustic wave (BAW) device comprising:
a first electrode;
a second electrode;
a piezoelectric layer coupled with and between the first and second electrodes; and
a reflector stack coupled with the second electrode and having a reflector layer to provide temperature compensation, the reflector layer having a thickness that is at least half an acoustic longitudinal wavelength at a frequency of a main resonance of the BAW device, wherein the reflector layer is a topmost layer of the reflector stack and the reflector stack further includes another reflector layer that has a thickness at least half of the acoustic longitudinal wavelength.
7. A bulk-acoustic wave (BAW) device comprising:
a resonator with a pair of electrodes and a piezoelectric layer;
and a reflector stack coupled with the resonator, the reflector stack including a topmost layer that is in an over-moded configuration that is to provide a plurality of mirror modes.
8. The BAW device of claim 7 , wherein the topmost layer is configured to include approximately 20% or more of energy of an acoustic wave in the BAW device.
9. The BAW device of claim 8 , wherein the topmost layer is configured to include approximately 30% of the energy of the acoustic wave in the BAW device.
10. The BAW device of claim 7 , wherein the topmost layer has a thickness that is at least half of an acoustic longitudinal wavelength at a frequency of a main resonance of the BAW device.
11. The BAW device of claim 10 , wherein the thickness is between approximately ¾ of the acoustic longitudinal wavelength and ⅘ of the acoustic longitudinal wavelength.
12. The BAW device of claim 7 , wherein the topmost layer comprises a silicon dioxide layer.
13. The BAW device of claim 7 , wherein the BAW device is a solidly mounted resonator (SMR) and the reflector stack includes alternating silicon dioxide and tungsten layers.
14. The BAW device of claim 7 , wherein the reflector stack includes another layer that is in an over-moded configuration.
15. The BAW device of claim 14 , wherein the other layer that is in an over-moded configuration is to facilitate a reduction of a magnitude of mirror modes in the BAW device.
16. The BAW device of claim 7 , wherein the topmost reflector layer has a first acoustical impedance and another layer of the reflector stack has a second acoustical impedance that is greater than the first acoustical impedance.
17. The BAW device of claim 15 , wherein the reflector stack includes alternating layers of first acoustical impedance and second acoustical impedance.
18. A system comprising:
an antenna structure;
a transceiver coupled with the antenna structure and configured to receive or transmit radio frequency signals, the transceiver including a filter that has a temperature compensated bulk acoustic wave (BAW) device having:
a resonator configured to convert energy between an acoustic wave form and an electrical form; and
a reflector coupled with the resonator and having a temperature compensating layer that is configured to have approximately 20% or more of energy of an acoustic wave in the BAW device.
19. The system of claim 18 , wherein the temperature compensating layer has a thickness that is at least half of an acoustic longitudinal wavelength at a frequency of a main resonance of the BAW device.
20. The system of claim 18 , wherein the reflector includes another temperature compensating layer that has a thickness of at least half of the acoustic longitudinal wavelength.
21. A method of manufacturing a bulk acoustic wave (BAW) device comprising:
providing a substrate;
forming a plurality of reflector layers on the substrate, wherein a topmost reflector layer has a thickness that is between approximately ¾ of an acoustic longitudinal wavelength and ⅘ of the acoustic longitudinal wavelength at a frequency of a main resonance of the BAW device; and
forming a resonator on the topmost reflector layer.
22. A method of manufacturing a bulk acoustic wave (BAW) device comprising:
providing a substrate;
forming a plurality of reflector layers on the substrate, wherein a topmost reflector layer has a thickness that is at least half of an acoustic longitudinal wavelength at a frequency of a main resonance of the BAW device and another reflector layer with a thickness that is at least half of the acoustic longitudinal wavelength; and
forming a resonator on the topmost reflector layer.