Thin-Film Surface-Acoustic-Wave Filter Using Lithium Niobate

An apparatus for filtering, the apparatus comprising:

• at least one surface-acoustic-wave filter configured to generate a filtered signal from a radio-frequency signal, the surface-acoustic-wave filter comprising:
• electrode means for converting the radio-frequency signal into an acoustic wave and converting a propagated acoustic wave into the filtered signal;
• and
• piezoelectric means for propagating the acoustic wave across a planar surface to produce the propagated acoustic wave, wherein:
• a first filter (X) axis is along the planar surface;
• a second filter (Y) axis is along the planar surface and perpendicular to the first filter (X) axis;
• a third filter (Z) axis is normal to the planar surface;
• an orientation of the first filter (X) axis, the second filter (Y) axis, and the third filter (Z) axis is relative to a crystalline structure of the piezoelectric means as defined by Euler angles lambda (λ), mu (μ), and theta (θ);
• and
• a value of the Euler angle mu (μ) has a range approximately from −70° to −55° or at least one symmetrical equivalent.

A method performed by a surface-acoustic-wave filter, the method comprising:

• converting a radio-frequency signal into an acoustic wave using an electrode structure of the surface-acoustic-wave filter;
• propagating the acoustic wave across a piezoelectric layer of the surface-acoustic-wave filter, the piezoelectric layer comprising lithium niobate (LiNbO3) material having a planar surface, including propagating the acoustic wave across the planar surface of the lithium niobate material in a direction along a first filter (X) axis, wherein:
• a second filter (Y) axis is along the planar surface and perpendicular to the first filter (X) axis;
• a third filter (Z) axis is normal to the planar surface;
• an orientation of the first filter (X) axis, the second filter (Y) axis, and the third filter (Z) axis is relative to a crystalline structure of the lithium niobate material as defined by Euler angles lambda (μ), mu (μ), and theta (θ);
• and
• a value of the Euler angle mu (μ) has a range approximately from −70° to −55° or at least one symmetrical equivalent;
• and
• converting the propagated acoustic wave into a filtered signal using the electrode structure.

A piezoelectric apparatus comprising lithium niobate (LiNbO3) material having a planar surface, the lithium niobate material configured to enable propagation of an acoustic wave across the planar surface in a direction along a first filter (X) axis, wherein:

• a second filter axis (Y) is along the planar surface and perpendicular to the first filter (X) axis;
• a third filter (Z) axis is normal to the planar surface;
• an orientation of the first filter (X) axis, the second filter (Y) axis, and the third filter (Z) axis is relative to a crystalline structure of the lithium niobate material as defined by Euler angles lambda (λ), mu (μ), and theta (θ);
• and
• a value of the Euler angle mu (μ) has a range approximately from −70° to −55° or at least one symmetrical equivalent.