ELECTROACOUSTIC RESONATOR AND RF FILTER COMPRISING AN ELECTROACOUSTIC RESONATOR

1 . An electroacoustic resonator, comprising

a piezoelectric material and

an electrode structure on the piezoelectric material,

wherein

an acoustic main mode having the wavelength λ can propagate,

the piezoelectric material is lithium niobate or doped lithium niobate and

has a crystal cut defined by the Euler angles (0°, 80° to 88°, 0°).

2 . The resonator of claim 1 , wherein the piezoelectric material has a crystal cut defined by the Euler angles (0°, 80° to 83°, 0°).

3 . The resonator of claim 1 , further comprising a TCF layer arranged on or above the electrode structure and the piezoelectric material.

4 . The resonator of claim 3 , wherein the TCF layer comprises SiO 2 or SiOF.

5 . The resonator of claim 3 , wherein the TCF layer has a thickness of 20% to 40% λ.

6 . The resonator of claim 1 , further comprising a passivation layer arranged on or above the TCF layer.

7 . The resonator of claim 6 , wherein the passivation layer comprises SiN.

8 . The resonator of claim 6 , wherein the passivation layer has a thickness of 1% to 4% λ.

9 . The resonator of claim 1 , wherein the electrode structure comprises a metal selected from Au, Cu, Pt and W.

10 . The resonator of claim 1 , wherein the electrode structure has a thickness of 6% to 15% λ.

11 . The resonator of claim 1 , wherein the main mode is a shear mode or a shear-like mode.

12 . The resonator of claim 1 , being a SAW resonator or a GBAW resonator.

13 . An RF filter comprising a resonator of claim 1 .

14 . The RF filter of claim 13 , being a band pass filter for band 28, 71, 41, 42 or 43.

15 . The RF filter of claim 13 , being a band pass filter for band 3, 8, 20 or 26.

16 . The RF filter of claim 13 , being a band pass filter for band 40, 48, 66 or 68.