Multi-mode coupling acoustic resonator, filter and radio frequency equipment

Abstract

The invention provides a multi-mode coupling acoustic resonator, a filter and radio frequency equipment, and relates to the technical field of acoustic resonators. According to the multi-mode coupling acoustic wave resonator, the material of a piezoelectric layer is selected, and the value range of an in-plane Euler angle is set, so that piezoelectric coefficients of the piezoelectric layer comprise an e11 component, an e13 component and an e34 component in a piezoelectric coefficient matrix; by designing the ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigital electrode, a transverse electric field and a longitudinal electric field exist in the piezoelectric layer at the same time when voltage is applied to the interdigital electrode; and by designing the ratio of the thickness of the interdigital electrode to the thickness of the piezoelectric layer, the integral of the dot product of the electric field and the alternating stress field in the piezoelectric layer in the thickness direction of the piezoelectric layer is not zero, so that the transverse electric field and the longitudinal electric field excite a multi-mode coupling acoustic wave at the same time, and the multi-mode coupling acoustic wave resonator has the advantages of ultrahigh working frequency, low cost and the like. And the material has a large electromechanical coupling coefficient, and can meet the large bandwidth requirement of centimeter wave communication frequency bands.

Description

Technical Field

[0001] This application relates to the field of acoustic resonator technology, and in particular to a multimode coupled acoustic resonator, filter, and radio frequency device. Background Technology

[0002] The large-scale deployment of fifth-generation (5G) mobile communication technology and the research and development of sixth-generation technologies are driving the continuous expansion of wireless communication spectrum resources to higher frequency bands. Among them, the centimeter wave band (usually referring to 7GHz to 24GHz) has become a core carrier for key scenarios such as ultra-high speed (eMBB), ultra-reliable and low-latency communications (uRLLC), and massive machine-type communications (mMTC) due to its ability to provide large-bandwidth continuous spectrum. However, the upgrade of the spectrum has placed unprecedented performance requirements on radio frequency front-end modules, especially their "spectrum gateway" filters.

[0003] Acoustic technology, due to its high quality factor and miniaturization advantages, is considered an ideal path to achieve high-performance micro-filters. Specifically in the centimeter-wave band, the demand for acoustic resonators and filters focuses primarily on ultra-high frequencies and large bandwidths. To support high-speed data transmission, filters must achieve high absolute bandwidths; for example, achieving a 5% relative bandwidth at a 6GHz center frequency requires an absolute bandwidth of 300MHz. Bandwidth (BW) is proportional to the electromechanical coupling coefficient of the resonator; therefore, achieving large bandwidths essentially involves seeking and exciting high-k resonators. 2 The acoustic resonance mode.

[0004] Currently, mainstream acoustic filtering technologies all exhibit fundamental limitations when facing the dual demands of ultra-high frequencies and large bandwidths. For example, traditional surface acoustic wave resonators typically operate below 3 GHz due to their low sound velocity; while bulk acoustic wave technology can operate at higher frequencies, its resonant frequency depends on the thickness of the piezoelectric film. Pursuing ultra-high frequencies (>8 GHz) inevitably requires the use of extremely thin piezoelectric films, which not only brings serious challenges to process reliability, but more importantly, the inherent limited electromechanical coupling coefficient of its traditional longitudinal bulk wave mode fundamentally limits the maximum achievable bandwidth.

[0005] Therefore, the existing technical architecture can hardly achieve the synergy of high frequency, large bandwidth and high performance in the centimeter wave high frequency band, which has become a key obstacle restricting the development of the next generation of radio frequency front-end. At present, there is an urgent need for a new acoustic mode that can break through the limitations of the existing acoustic mode. Summary of the Invention

[0006] In view of the above problems, this application provides a multimode coupled acoustic resonator, filter, and radio frequency device, which breaks through the traditional constraint relationship between the acoustic mode order and the electromechanical coupling coefficient, significantly increasing the electromechanical coupling coefficient of the acoustic resonator, and can meet the ultra-high frequency and large bandwidth requirements of centimeter-wave communication. The specific solution is as follows:

[0007] A first aspect of this application provides a multimode coupled acoustic resonator, the multimode coupled acoustic resonator comprising:

[0008] Substrate;

[0009] A piezoelectric layer located on one side of the substrate; the material of the piezoelectric layer is an anisotropic piezoelectric material;

[0010] Interdigitated electrodes located on the side of the piezoelectric layer opposite to the substrate;

[0011] In the plane containing the piezoelectric layer, the angle between the positive direction of the X-axis in the global coordinate system of the piezoelectric material and the first direction is taken as the in-plane Euler angle of the piezoelectric material; the value range of the in-plane Euler angle is a first preset range, such that the piezoelectric coefficient of the piezoelectric layer includes e in the piezoelectric coefficient matrix. 11 Components, e 13 Components and e 34 Component; wherein the first direction is perpendicular to the length extension direction of the interdigitated electrode;

[0012] The ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrode is within a second preset range, so that when a voltage is applied to the interdigitated electrode, both a transverse electric field and a longitudinal electric field exist in the piezoelectric layer.

[0013] The ratio of the thickness of the interdigitated electrode to the thickness of the piezoelectric layer is within a third preset range, such that the integral of the dot product of the electric field and the alternating stress field within the piezoelectric layer in the thickness direction of the piezoelectric layer is not zero.

[0014] Preferably, in the above-mentioned multimode coupled acoustic resonator, the piezoelectric layer is a lithium niobate layer or a lithium tantalate layer.

[0015] Preferably, in the above-mentioned multimode coupled acoustic resonator, when the piezoelectric layer is an X-shaped lithium niobate layer,

[0016] The first preset range is -10° to 62°, or -190° to -118°, including endpoint values;

[0017] When the piezoelectric layer is an X-oriented lithium tantalate layer

[0018] The first preset range is -8° to 56°, or -188° to -124°, including endpoint values.

[0019] Preferably, in the above-mentioned multimodal coupled acoustic resonator, the second preset range is 0.3-0.6, including the endpoint value.

[0020] Preferably, in the above-mentioned multimodal coupled acoustic resonator, the third preset range is 0.3-0.7, including the endpoint value.

[0021] Preferably, in the above-mentioned multimode coupled acoustic resonator, the substrate is a silicon carbide substrate, a sapphire substrate, a diamond substrate, a gallium nitride substrate, or a silicon substrate.

[0022] Preferably, in the above-mentioned multimode coupled acoustic resonator, the interdigitated electrode is a single-layer metal layer or a multi-layer stacked metal layer;

[0023] The interdigitated electrodes are made of aluminum, nickel, copper, platinum, gold, silver, tungsten, molybdenum, chromium, titanium, or iron.

[0024] Preferably, in the above-mentioned multimodal coupled acoustic resonator, the number of interdigital electrodes ranges from 2 to 500, including the endpoint values;

[0025] The width of the interdigitated electrode in the first direction ranges from 0.001 μm to 5 μm, including the endpoint value;

[0026] The length of the interdigitated electrode ranges from 1 μm to 500 μm, including the endpoint values.

[0027] A second aspect of this application provides a filter, the filter comprising any of the above-described multimode coupled acoustic resonators.

[0028] A third aspect of this application provides a radio frequency device, the radio frequency device including any of the above-mentioned multimode coupled acoustic resonators;

[0029] Alternatively, the radio frequency device may include the aforementioned filter.

[0030] By employing the above technical solutions, this application provides a multimode coupled acoustic resonator, filter, and radio frequency device. The multimode coupled acoustic wave includes a second-order horizontal shear mode acoustic wave. Traditional acoustic resonators using a single piezoelectric layer cannot excite second-order horizontal shear mode acoustic waves because the integral of the dot product of the electric field and alternating stress field within the piezoelectric layer along the thickness direction of the piezoelectric layer is zero, i.e., the electromechanical coupling coefficient is zero. However, this application, by designing the ratio of the thickness of the interdigitated electrodes to the thickness of the piezoelectric layer, ensures that the integral of the dot product of the electric field and alternating stress field within the piezoelectric layer along the thickness direction of the piezoelectric layer is not zero. This successfully excites a multimode coupled acoustic wave containing a second-order horizontal shear mode acoustic wave within a single piezoelectric layer, with a sound velocity almost twice that of the traditional basic mode acoustic wave. Therefore, this multimode coupled acoustic resonator can operate in the centimeter-wave frequency band.

[0031] Secondly, the electromechanical coupling coefficient of traditional high-order modal acoustic resonators decreases quadratically with increasing order. For example, the electromechanical coupling coefficient of a second-order horizontal shear mode acoustic resonator is approximately one-quarter that of a zero-order horizontal shear mode acoustic resonator. This application, however, selects anisotropic piezoelectric materials for the piezoelectric layer and designs the range of in-plane Euler angles to ensure that the piezoelectric coefficient of the piezoelectric layer includes the values ​​of e in the piezoelectric coefficient matrix. 11 Components, e 13 Components and e 34 The components were determined, and the ratio of the piezoelectric layer thickness to the periodic wavelength of the interdigitated electrodes was designed so that when a voltage is applied to the interdigitated electrodes, both transverse and longitudinal electric fields exist simultaneously in the piezoelectric layer, thus making e 11 Components, e 13 Components and e 34 The component is also used to excite multimodal coupled acoustic waves, breaking through the traditional constraint relationship between the mode order of acoustic waves and the electromechanical coupling coefficient, and greatly increasing the electromechanical coupling coefficient of the acoustic resonator.

[0032] Based on this design, the multimode coupled acoustic resonator proposed in this application has an electromechanical coupling coefficient of up to 19% at a resonant frequency of 9.1 GHz, which can meet the ultra-high frequency and large bandwidth requirements of centimeter wave communication. Attached Figure Description

[0033] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0034] Figure 1 A schematic diagram of a two-dimensional cross-sectional structure of a multimode coupled acoustic resonator provided in an embodiment of the present invention;

[0035] Figure 2This is a schematic diagram of the structure of an interdigitated electrode provided in an embodiment of the present invention;

[0036] Figure 3 This is a three-dimensional schematic diagram of the internal Euler angle rotation of a piezoelectric material in a global coordinate system, provided as an embodiment of the present invention.

[0037] Figure 4 This is a schematic diagram of the two-dimensional cross-sectional polarization displacement of a multimode coupled acoustic resonator provided in an embodiment of the present invention;

[0038] Figure 5 A schematic diagram illustrating the range of values ​​for in-plane Euler angles provided in an embodiment of the present invention;

[0039] Figure 6 A schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.32 GHz under one embodiment of the present invention.

[0040] Figure 7 A schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.16 GHz under a second embodiment of the present invention.

[0041] Figure 8 A schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.12 GHz under a scheme of Embodiment 3 of the present invention;

[0042] Figure 9 A schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.88 GHz under a scheme of Embodiment 4 of the present invention;

[0043] Figure 10 A schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 8.79 GHz under a scheme of Embodiment 5 provided by the present invention;

[0044] Figure 11 A schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 8.84 GHz under a sixth embodiment of the present invention.

[0045] Figure 12 This is a schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.98 GHz under a scheme of Embodiment Seven provided by the present invention. Detailed Implementation

[0046] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is only for explaining specific embodiments and is not intended to limit the application. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0047] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] It should be noted that the directional terms used in this invention are based on the relative positional relationships shown in the accompanying drawings and should not be taken as absolute limitations on this application.

[0049] Various modifications and variations can be made to this invention without departing from its spirit or scope, as will be apparent to those skilled in the art. Therefore, this invention is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the embodiments provided in this invention can be combined with each other without contradiction.

[0050] refer to Figure 1 , Figure 1 This is a schematic diagram of a two-dimensional cross-sectional structure of a multimode coupled acoustic resonator provided in an embodiment of the present invention, with reference to... Figure 2 , Figure 2 This is a schematic diagram of the structure of an interdigitated electrode provided in an embodiment of the present invention, with reference to... Figure 3 , Figure 3 This is a three-dimensional schematic diagram of the internal Euler angle rotation of a piezoelectric material in a global coordinate system, provided as an embodiment of the present invention. The multimode coupled acoustic resonator provided in this embodiment includes: a substrate 11.

[0051] A piezoelectric layer 12 is located on one side of the substrate 11; the material of the piezoelectric layer 12 is an anisotropic piezoelectric material.

[0052] Interdigitated electrodes 13 are located on the side of the piezoelectric layer 12 opposite to the substrate 11.

[0053] In the plane containing the piezoelectric layer 12, the angle between the positive direction of the X-axis in the global coordinate system of the piezoelectric material and the first direction S is taken as the in-plane Euler angle α of the piezoelectric material; the value range of the in-plane Euler angle α is a first preset range, so that the piezoelectric coefficient of the piezoelectric layer 12 includes e in the piezoelectric coefficient matrix. 11 Components, e 13 Components and e 34Component; wherein, the first direction S is perpendicular to the length extension direction V of the interdigital electrode 13.

[0054] The ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigital electrode 13, H1 / λ, is within a second preset range, so that when a voltage is applied to the interdigital electrode 13, both a transverse electric field and a longitudinal electric field exist simultaneously in the piezoelectric layer 12.

[0055] The ratio H2 / H1 of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12 is within a third preset range, so that the integral of the dot product of the electric field and the alternating stress field in the piezoelectric layer 12 in the thickness direction of the piezoelectric layer 12 is not zero. Therefore, the transverse electric field and the longitudinal electric field simultaneously excite a multimodal coupled acoustic wave.

[0056] The multimodal coupled acoustic wave is composed of three different types of coupled acoustic waves, wherein the transverse electric field excitation e 11 The component generates a longitudinal wave with a polarization direction parallel to the plane of the piezoelectric layer 12 and perpendicular to the length extension direction V of the interdigitated electrode 13, and the transverse electric field excites e 13 The component generates a first-order symmetric mode acoustic wave with a polarization direction perpendicular to the plane of the piezoelectric layer 12, and the longitudinal electric field excites e 34 The component generates a second-order horizontal shear mode acoustic wave with a polarization direction parallel to the plane of the piezoelectric layer 12 and parallel to the length extension direction V of the interdigitated electrode 13.

[0057] refer to Figure 4 , Figure 4 This is a schematic diagram of the two-dimensional cross-sectional polarization displacement of a multimode coupled acoustic resonator provided in an embodiment of the present invention; the polarization displacement direction of the longitudinal wave is perpendicular to the length extension direction V of the interdigital electrode 13, i.e., the S direction; the polarization displacement direction of the first-order symmetric mode acoustic wave is perpendicular to the plane where the piezoelectric layer 12 is located, i.e., the Z direction; the polarization displacement direction of the second-order horizontal shear mode acoustic wave is parallel to the plane where the piezoelectric layer 12 is located and parallel to the length extension direction V of the interdigital electrode 13. The multimode coupled acoustic wave simultaneously possesses these three polarization displacements.

[0058] Specifically, in the embodiments of the present invention, such as Figure 3 As shown, the XYZ coordinate system is the global coordinate system of the piezoelectric material. The X-axis, Y-axis and Z-axis are perpendicular to each other. The Z-axis is perpendicular to the plane where the piezoelectric layer 12 is located, and the X-axis and Y-axis are parallel to the plane where the piezoelectric layer 12 is located.

[0059] Anisotropic piezoelectric materials possess a fixed crystal coordinate system, which is bound to its crystal axis. For example, lithium niobate crystals belong to the trigonal crystal system. To facilitate the description of its crystal orientation and crystal planes, the industry commonly uses a Cartesian coordinate system based on the hexagonal crystal system. In this system, the Z-axis of the lithium niobate crystal coincides with the c-axis of the hexagonal crystal system, i.e., the cubic symmetry axis of the lithium niobate crystal. The X-axis of the lithium niobate crystal is taken from any a-axis of the hexagonal crystal system. H The Y-axis direction is determined by first determining the direction of the lithium niobate crystal, and then by using the right-hand rule of the Cartesian coordinate system.

[0060] In the embodiments of this application, the global coordinate system and the crystal coordinate system of the piezoelectric material have a one-to-one correspondence. For example, if the piezoelectric material is X-tangential lithium niobate, then the X-axis of the global coordinate system is parallel to the Y-axis of the crystal coordinate system, the Y-axis of the global coordinate system is parallel to the Z-axis of the crystal coordinate system, and the Z-axis of the global coordinate system is parallel to the X-axis of the crystal coordinate system; if the piezoelectric material is Y-tangential lithium niobate, then the X-axis of the global coordinate system is parallel to the X-axis of the crystal coordinate system, the Y-axis of the global coordinate system is parallel to the Z-axis of the crystal coordinate system, and the Z-axis of the global coordinate system is parallel to the Y-axis of the crystal coordinate system; if the piezoelectric material is Z-tangential lithium niobate, then the X-axis of the global coordinate system is parallel to the X-axis of the crystal coordinate system, the Y-axis of the global coordinate system is parallel to the Y-axis of the crystal coordinate system, and the Z-axis of the global coordinate system is parallel to the Z-axis of the crystal coordinate system.

[0061] First, as described above, the multimodal coupled acoustic wave in this embodiment of the invention includes a second-order horizontal shear mode acoustic wave. Traditional acoustic resonators using a single piezoelectric layer cannot excite second-order horizontal shear mode acoustic waves because the integral of the dot product of the electric field and alternating stress field within the piezoelectric layer along the thickness direction of the piezoelectric layer is zero, i.e., the electromechanical coupling coefficient is zero. However, this application designs the ratio H2 / H1 of the thickness H2 of the interdigital electrode 13 to the thickness H1 of the piezoelectric layer 12, ensuring that the integral of the dot product of the electric field and alternating stress field within the piezoelectric layer 12 along the thickness direction of the piezoelectric layer 12 is not zero. This successfully excites a multimodal coupled acoustic wave containing a second-order horizontal shear mode acoustic wave within a single piezoelectric layer 12, with a sound velocity almost twice that of a traditional basic mode acoustic wave. Therefore, this multimodal coupled acoustic resonator can operate in the centimeter-wave frequency band.

[0062] Secondly, the electromechanical coupling coefficient of traditional high-order modal acoustic resonators decreases quadratically with increasing order. For example, the electromechanical coupling coefficient of a second-order horizontal shear mode acoustic resonator is approximately one-quarter that of a zero-order horizontal shear mode acoustic resonator. However, this application selects an anisotropic piezoelectric material for the piezoelectric layer 12 and designs the range of values ​​for the in-plane Euler angle α, so that the piezoelectric coefficient of the piezoelectric layer 12 includes the values ​​of e in the piezoelectric coefficient matrix. 11 Components, e 13 Components and e 34The components are determined, and the ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigital electrode 13, H1 / λ, is designed so that when a voltage is applied to the interdigital electrode 13, both a transverse electric field and a longitudinal electric field exist simultaneously in the piezoelectric layer 12, thus making e 11 Components, e 13 Components and e 34 The component is also used to excite multimodal coupled acoustic waves, breaking through the traditional constraint relationship between the mode order of acoustic waves and the electromechanical coupling coefficient, and greatly increasing the electromechanical coupling coefficient of the acoustic resonator.

[0063] Based on this design, the multimode coupled acoustic resonator proposed in this application has an electromechanical coupling coefficient of up to 19% at a resonant frequency of 9.1 GHz, which can meet the ultra-high frequency and large bandwidth requirements of centimeter wave communication.

[0064] In an optional embodiment of the present invention, the piezoelectric layer 12 is a lithium niobate layer or a lithium tantalate layer.

[0065] Specifically, in the embodiments of the present invention, reference is made to... Figure 5 , Figure 5 This is a schematic diagram illustrating the range of values ​​for in-plane Euler angles provided in an embodiment of the present invention, as shown below. Figure 5 As shown in (a), when the piezoelectric layer 12 is an X-oriented lithium niobate layer, the first preset range is -10° to 62°, or -190° to -118°, including the endpoint values, and the piezoelectric coefficient e is given. 11 Components, e 13 Components and e 34 The absolute values ​​of all components are greater than 1; for example... Figure 5 As shown in (b), when the piezoelectric layer 12 is an X-oriented lithium tantalate layer, the first preset range is -8° to 56°, or -188° to -124°, including the endpoint values, at which time the piezoelectric coefficient e 11 Components, e 13 Components and e 34 The absolute values ​​of all components are greater than 0.8.

[0066] In an optional embodiment of the present invention, the second preset range is 0.3-0.6, including endpoint values.

[0067] For example, the ratio H1 / λ of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigitated electrode 13 can be 0.3, 0.5, or 0.6, etc.

[0068] In an optional embodiment of the present invention, the third preset range is 0.3-0.7, including endpoint values.

[0069] For example, the ratio H2 / H1 of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12 can be 0.3, 0.4 or 0.7, etc.

[0070] In an optional embodiment of the present invention, the substrate 11 includes, but is not limited to, a silicon carbide substrate, a sapphire substrate, a diamond substrate, a gallium nitride substrate, or a silicon substrate.

[0071] In an optional embodiment of the present invention, the interdigitated electrode 13 is a single-layer metal layer or a multi-layer metal layer.

[0072] The materials of the interdigitated electrodes 13 include, but are not limited to, aluminum, nickel, copper, platinum, gold, silver, tungsten, molybdenum, chromium, titanium, or iron.

[0073] It should be noted that when the interdigitated electrode 13 is a multilayer stacked metal layer, the materials of the multilayer stacked metal layers can be the same, or at least two of the multilayer stacked metal layers can be made of different materials.

[0074] In an optional embodiment of the present invention, the number of interdigital electrodes 13 ranges from 2 to 500, including the endpoint value.

[0075] For example, the number of interdigital electrodes 13 can be 2, 100, 356, 423, or 500. Figure 2 As shown, the example is given with 10 interdigitated electrodes 13.

[0076] The width of the interdigitated electrode 13 in the first direction S ranges from 0.001 μm to 5 μm, including the endpoint value.

[0077] For example, the width of the interdigitated electrode 13 in the first direction S can be 0.001 μm, 1 μm, 2.5 μm or 5 μm, etc.

[0078] The length of the interdigitated electrode 13 ranges from 1 μm to 500 μm, including the endpoint value.

[0079] For example, the length of the interdigitated electrode 13 can be 1μm, 88μm, 156μm, 348μm or 500μm, etc.

[0080] The performance of the multimode coupled acoustic resonator provided in this application will be further described below with specific embodiments.

[0081] Example 1

[0082] The piezoelectric layer 12 is an X-shaped lithium niobate layer with an in-plane Euler angle α of 29°. The ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigitated electrode 13, H1 / λ, is 0.41, and the ratio of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12, H2 / H1, is 0.43. The interdigitated electrode 13 is a single-layer metal layer made of copper.

[0083] refer to Figure 6 , Figure 6 This is a schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.32 GHz under the scheme of Embodiment 1 of the present invention. Its electromechanical coupling coefficient can be obtained through calculation. It is 19.5%.

[0084] electromechanical coupling coefficient The calculation formula is:

[0085] ;

[0086] in, This is the series resonant frequency of the multimode coupled acoustic resonator; This is the parallel resonant frequency of the multimode coupled acoustic resonator.

[0087] Example 2

[0088] The piezoelectric layer 12 is an X-shaped lithium niobate layer with an in-plane Euler angle α of 29°. The ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigitated electrode 13, H1 / λ, is 0.43, and the ratio of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12, H2 / H1, is 0.47. The interdigitated electrode 13 is a double metal layer, one of which is made of copper and the other of which is made of aluminum.

[0089] refer to Figure 7 , Figure 7 This is a schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.16 GHz under the second embodiment of the present invention. Its electromechanical coupling coefficient can be calculated. It is 18.4%.

[0090] Example 3

[0091] The piezoelectric layer 12 is an X-shaped lithium niobate layer with an in-plane Euler angle α of 29°. The ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigitated electrode 13, H1 / λ, is 0.43, and the ratio of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12, H2 / H1, is 0.36. The interdigitated electrode 13 is a double metal layer, one of which is made of copper and the other of which is made of gold.

[0092] refer to Figure 8 , Figure 8 This is a schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.12 GHz under the scheme of Embodiment 3 of the present invention. Its electromechanical coupling coefficient can be obtained through calculation. It is 18.8%.

[0093] Example 4

[0094] The piezoelectric layer 12 is an X-shaped lithium niobate layer with an in-plane Euler angle α of 29°. The ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigitated electrode 13, H1 / λ, is 0.46, and the ratio of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12, H2 / H1, is 0.47. The interdigitated electrode 13 is a single-layer metal layer made of nickel.

[0095] refer to Figure 9 , Figure 9 This is a schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.88 GHz under the fourth embodiment of the present invention. Its electromechanical coupling coefficient can be calculated. It is 14.6%.

[0096] Example 5

[0097] The piezoelectric layer 12 is an X-shaped lithium niobate layer with an in-plane Euler angle α of 29°. The ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigitated electrode 13, H1 / λ, is 0.4, and the ratio of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12, H2 / H1, is 0.63. The interdigitated electrode 13 is a double metal layer, one of which is made of nickel and the other of which is made of aluminum.

[0098] refer to Figure 10 , Figure 10 This is a schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 8.79 GHz under the fifth embodiment of the present invention. Its electromechanical coupling coefficient can be calculated. It is 17.4%.

[0099] Example 6

[0100] The piezoelectric layer 12 is an X-shaped lithium niobate layer with an in-plane Euler angle α of 29°. The ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigitated electrode 13, H1 / λ, is 0.4, and the ratio of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12, H2 / H1, is 0.49. The interdigitated electrode 13 is a double metal layer, one of which is made of nickel and the other of which is made of gold.

[0101] refer to Figure 11 , Figure 11This is a schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 8.84 GHz under the sixth embodiment of the present invention. Its electromechanical coupling coefficient can be calculated. It is 16.7%.

[0102] Example 7

[0103] The piezoelectric layer 12 is an X-shaped lithium niobate layer with an in-plane Euler angle α of 20°. The ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigitated electrode 13, H1 / λ, is 0.47. The ratio of the thickness H2 of the interdigitated electrode 13 to the thickness H1 of the piezoelectric layer 12, H2 / H1, is 0.47. The interdigitated electrode 13 is a single-layer metal layer made of nickel.

[0104] refer to Figure 12 , Figure 12 This is a schematic diagram of the simulated admittance curve of a multimode coupled acoustic resonator operating at 9.98 GHz under the seventh embodiment of the present invention. Its electromechanical coupling coefficient can be calculated. It is 16.6%.

[0105] As described above, in the multimode coupled acoustic resonator provided by this application, by selecting the material of the piezoelectric layer 12 and setting the range of the in-plane Euler angle α, the piezoelectric coefficient of the piezoelectric layer 12 includes the e in the piezoelectric coefficient matrix. 11 Components, e 13 Components and e 34 The components are designed such that, by setting the ratio of the thickness H1 of the piezoelectric layer 12 to the periodic wavelength λ of the interdigital electrode 13 to H1 / λ, a transverse electric field and a longitudinal electric field exist simultaneously in the piezoelectric layer 12 when a voltage is applied to the interdigital electrode 13; and by setting the ratio of the thickness H2 of the interdigital electrode 13 to the thickness H1 of the piezoelectric layer 12 to H2 / H1, the integral of the dot product of the electric field and the alternating stress field in the piezoelectric layer 12 along the thickness direction of the piezoelectric layer 12 is not zero. Therefore, the transverse electric field and the longitudinal electric field simultaneously excite a multimode coupled acoustic wave.

[0106] The multimodal coupled acoustic wave is composed of three different types of coupled acoustic waves, among which the transverse electric field excitation e 11 The component generates a longitudinal wave with a polarization direction parallel to the plane of the piezoelectric layer 12 and perpendicular to the length extension direction V of the interdigitated electrode 13, and the transverse electric field excites e 13 The component generates a first-order symmetric mode acoustic wave with a polarization direction perpendicular to the plane of the piezoelectric layer 12, and the longitudinal electric field excites e 34 The component generates a second-order horizontal shear mode acoustic wave with a polarization direction parallel to the plane of the piezoelectric layer 12 and parallel to the length extension direction V of the interdigitated electrode 13.

[0107] The multimode coupled acoustic resonator provided in this application not only successfully excites multimode coupled acoustic waves containing second-order horizontal shear mode acoustic waves within a single piezoelectric layer 12, but also achieves a sound velocity almost twice that of traditional basic mode acoustic waves, thus enabling operation in the centimeter wave frequency band; furthermore, it enables e 11 Components, e 13 Components and e 34 The component is also used to excite multimodal coupled acoustic waves, breaking through the traditional constraint relationship between the mode order of acoustic waves and the electromechanical coupling coefficient, and greatly increasing the electromechanical coupling coefficient of the acoustic resonator.

[0108] Therefore, the multimode coupled acoustic resonator proposed in this application has an electromechanical coupling coefficient as high as 19% at a resonant frequency of 9.1 GHz, which can meet the ultra-high frequency and large bandwidth requirements of centimeter wave communication.

[0109] Based on the above embodiments of the present invention, another embodiment of the present invention also provides a filter, the filter including the multimode coupled acoustic resonator described in the above embodiments.

[0110] Based on the above embodiments of the present invention, another embodiment of the present invention also provides a radio frequency device, the radio frequency device including the multimode coupled acoustic resonator described in the above embodiments.

[0111] Alternatively, the radio frequency device may include the filter described in the above embodiments.

[0112] The above provides a detailed description of the multimode coupled acoustic resonator, filter, and radio frequency device provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0113] It should be noted that each embodiment in this specification focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0114] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that elements inherent to a process, method, article, or apparatus that comprises a list of elements, or elements inherent to such processes, methods, articles, or apparatus, are also included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0115] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multimode coupled acoustic resonator, characterized in that, The multimode coupled acoustic resonator includes: Substrate; A piezoelectric layer located on one side of the substrate; the material of the piezoelectric layer is an anisotropic piezoelectric material; Interdigitated electrodes located on the side of the piezoelectric layer opposite to the substrate; In the plane containing the piezoelectric layer, the angle between the positive direction of the X-axis in the global coordinate system of the piezoelectric material and the first direction is taken as the in-plane Euler angle of the piezoelectric material; the value range of the in-plane Euler angle is a first preset range, such that the piezoelectric coefficient of the piezoelectric layer includes e in the piezoelectric coefficient matrix. 11 Components, e 13 Components and e 34 Component; wherein the first direction is perpendicular to the length extension direction of the interdigitated electrode; The ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrode is within a second preset range, so that when a voltage is applied to the interdigitated electrode, both a transverse electric field and a longitudinal electric field exist in the piezoelectric layer. The ratio of the thickness of the interdigitated electrode to the thickness of the piezoelectric layer is within a third preset range, such that the integral of the dot product of the electric field and the alternating stress field within the piezoelectric layer in the thickness direction of the piezoelectric layer is not zero.

2. The multimode coupled acoustic resonator according to claim 1, characterized in that, The piezoelectric layer is a lithium niobate layer or a lithium tantalate layer.

3. The multimode coupled acoustic resonator according to claim 2, characterized in that, When the piezoelectric layer is an X-oriented lithium niobate layer, The first preset range is -10° to 62°, or -190° to -118°, including endpoint values; When the piezoelectric layer is an X-oriented lithium tantalate layer The first preset range is -8° to 56°, or -188° to -124°, including endpoint values.

4. The multimode coupled acoustic resonator according to claim 1, characterized in that, The second preset range is 0.3-0.6, including the endpoint values.

5. The multimode coupled acoustic resonator according to claim 1, characterized in that, The third preset range is 0.3-0.7, including the endpoint values.

6. The multimode coupled acoustic resonator according to claim 1, characterized in that, The substrate is a silicon carbide substrate, a sapphire substrate, a diamond substrate, a gallium nitride substrate, or a silicon substrate.

7. The multimode coupled acoustic resonator according to claim 1, characterized in that, The interdigitated electrode is a single metal layer or a multi-layer stacked metal layer; The interdigitated electrodes are made of aluminum, nickel, copper, platinum, gold, silver, tungsten, molybdenum, chromium, titanium, or iron.

8. The multimode coupled acoustic resonator according to claim 1, characterized in that, The number of interdigital electrodes ranges from 2 to 500, including endpoint values; The width of the interdigitated electrode in the first direction ranges from 0.001 μm to 5 μm, including the endpoint value; The length of the interdigitated electrode ranges from 1 μm to 500 μm, including the endpoint values.

9. A filter, characterized in that, The filter includes the multimode coupled acoustic resonator as described in any one of claims 1-8.

10. A radio frequency device, characterized in that, The radio frequency device includes the multimode coupled acoustic resonator as described in any one of claims 1-8; Alternatively, the radio frequency device may include the filter of claim 9.

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