Dispersive delay line with piezoelectric substrate
Dispersive delay lines are disclosed. A dispersive delay line can include a piezoelectric substrate having a first interdigital transducer electrode on a first region of the piezoelectric substrate and a second interdigital transducer electrode on a second region of the piezoelectric substrate. The dispersive delay line is arranged such that an acoustic wave is configured to propagate from the first interdigital transducer electrode to the second interdigital transducer electrode though a third region of the piezoelectric substrate. The third region of the piezoelectric substrate is configured as a waveguide and can have a thickness of less than half the wavelength of the acoustic wave. Related radio frequency modules, wireless communications devices, and methods are disclosed.
1. A dispersive delay line comprising:
a piezoelectric substrate including a first region, a second region, and a third region;
a first interdigital transducer electrode on the first region of the piezoelectric substrate; and
a second interdigital transducer electrode on the second region of the piezoelectric substrate, the dispersive delay line arranged such that a Lamb wave having a wavelength of λ is configured to propagate from the first interdigital transducer electrode to the second interdigital transducer electrode though the third region of the piezoelectric substrate, the third region of the piezoelectric substrate having a thickness that is less than 0.5λ and that is greater than a thickness of the first region of the piezoelectric substrate.
2. The dispersive delay line of claim 1 wherein the piezoelectric substrate includes aluminum nitride.
3. The dispersive delay line of claim 1 wherein the Lamb wave is a lowest order symmetric mode Lamb wave.
4. The dispersive delay line of claim 1 wherein the dispersive delay line has a passband of more than 0.5 gigahertz.
5. The dispersive delay line of claim 4 wherein the passband is less than 2 gigahertz.
6. The dispersive delay line of claim 1 wherein the dispersive delay line has a passband of more than 1 gigahertz.
7. The dispersive delay line of claim 6 wherein the dispersive delay line has a group delay in a range from 25 nanoseconds to 50 nanoseconds.
8. The dispersive delay line of claim 1 wherein the dispersive delay line has a group delay in a range from 20 nanoseconds to 150 nanoseconds.
9. The dispersive delay line of claim 1 wherein the dispersive delay line has an operating frequency in range from 5 gigahertz to 10 gigahertz.
10. The dispersive delay line of claim 1 wherein the dispersive delay line has an operating frequency of more than 10 gigahertz.
11. The dispersive delay line of claim 1 wherein the dispersive delay line has an operating frequency in Frequency Range 2 defined by a New Radio standard.
12. The dispersive delay line of claim 1 wherein the thickness of the third region of the piezoelectric substrate decreases adjacent to the first region and adjacent to the second region.
13. The dispersive delay line of claim 1 , wherein:
a first thickness of the piezoelectric substrate adjacent a first end of the third region proximal to the first interdigital transducer electrode is less than 0.5λ; and
a second thickness of the piezoelectric substrate adjacent a second end of the third region proximal to the second interdigital transducer is less than the first thickness of the piezoelectric substrate.
14. The dispersive delay line of claim 13 , wherein the thickness of the piezoelectric substrate in the third region is scaled linearly between the first thickness and the second thickness.
15. The dispersive delay line of claim 13 , wherein the thickness of the piezoelectric substrate in the third region is scaled non-linearly between the first thickness and the second thickness.
16. The dispersive delay line of claim 1 , wherein:
a first thickness of the piezoelectric substrate adjacent a first end of the third region proximal to the first interdigital transducer electrode is less than 0.5λ;
a second thickness of the piezoelectric substrate adjacent a second end of the third region proximal to the second interdigital transducer is less than or equal to the first thickness of the piezoelectric substrate; and
a third thickness of the piezoelectric substrate at a narrowed portion of the piezoelectric substrate located between the first and second ends in the third region is less than the second thickness.
17. The dispersive delay line of claim 16 , wherein the third thickness of the piezoelectric substrate is greater than or equal to a thickness of the piezoelectric substrate in the first region.
18. A radio frequency module comprising:
a dispersive delay line including a piezoelectric substrate including a first region, a second region, and a third region; a first interdigital transducer electrode on the first region of the piezoelectric substrate; and a second interdigital transducer electrode on the second region of the piezoelectric substrate, the dispersive delay line arranged such that a Lamb wave having a wavelength of λ is configured to propagate from the first interdigital transducer electrode to the second interdigital transducer electrode though the third region of the piezoelectric substrate, the third region of the piezoelectric substrate having a thickness that is less than 0.5λ and that is greater than a thickness of the first region of the piezoelectric substrate;
radio frequency circuitry coupled to the dispersive delay line; and
a packaging structure enclosing the dispersive delay line and the radio frequency circuitry.
19. The radio frequency module of claim 18 wherein the radio frequency circuitry includes a radio frequency amplifier.
20. A wireless communication device comprising:
a dispersive delay line including a piezoelectric substrate including a first region, a second region, and a third region; a first interdigital transducer electrode on the first region of the piezoelectric substrate; and a second interdigital transducer on the second region of the piezoelectric substrate, the dispersive delay line arranged such that a Lamb wave having a wavelength of λ is configured to propagate from the first interdigital transducer electrode to the second interdigital transducer electrode though the third region of the piezoelectric substrate, the third region of the piezoelectric substrate having a thickness that is less than 0.5λ and that is greater than a thickness of the first region of the piezoelectric substrate; and
an antenna in communication with the dispersive delay line.