Cascade resonator, filter and radio frequency front-end module

Abstract

The application relates to a kind of cascade resonator, filter and radio frequency front end module, including piezoelectric substrate, first interdigital transducer, second interdigital transducer and conductive structure;First interdigital transducer, second interdigital transducer and conductive structure are arranged on piezoelectric substrate, two interdigital transducers share a middle bus bar;At least one first cavity is provided on the middle bus bar, and the conductive structure is arranged in at least one first cavity;The middle surface of the conductive structure relative to the middle bus bar is asymmetric structure.Because the conductive structure relative to the middle surface is asymmetric structure, so the whole cascade resonator relative to the middle surface is also asymmetric structure, so it can change the transmission characteristics of cascade resonator, make the frequency of the two resonators cascaded together transverse mode stagger, avoid the resonance of transverse mode, thereby reduce the adverse effects caused by transverse mode superposition.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency filtering technology, and particularly relates to a cascaded resonator, filter and radio frequency front-end module. Background Technology

[0002] Cascaded resonators are often used in filters to improve power capacity and reduce nonlinearity. Cascaded resonators are often obtained by cascading the same surface acoustic wave resonators.

[0003] However, in some surface acoustic wave (SAW) resonators (such as TC-SAW (temperature compensated SAW) and IHP-SAW (high performance SAW), the transverse modes are not completely suppressed. Some transverse modes still exist in the SAW resonator. The transverse modes are represented on the admittance curve by a series of small peaks between the resonant and anti-resonant points. Therefore, when identical SAW resonators are cascaded, the amplitude of the transverse modes in the cascaded resonator will be enhanced, thus affecting the performance of the final cascaded resonator and filter. Summary of the Invention

[0004] This invention provides a cascaded resonator, filter, and RF front-end module, aiming to solve the problem that the amplitude of the transverse mode is enhanced when the same surface acoustic wave resonator is cascaded.

[0005] To address the aforementioned problems, embodiments of the present invention provide a cascaded resonator, comprising a piezoelectric substrate, a first interdigital transducer, a second interdigital transducer, and a conductive structure; the first interdigital transducer, the second interdigital transducer, and the conductive structure are disposed on the piezoelectric substrate, and the first interdigital transducer and the second interdigital transducer share an intermediate busbar; the intermediate busbar has at least one first cavity, and the conductive structure is disposed within at least one first cavity; the conductive structure is asymmetrical with respect to the middle surface of the intermediate busbar; along a first direction, the intermediate busbar includes a first surface and a second surface disposed opposite to each other, the first surface and the second surface being symmetrical with respect to the middle surface; the first direction is parallel to the arrangement direction of the first interdigital transducer and the second interdigital transducer.

[0006] Optionally, the first cavity is disposed on the surface of the intermediate busbar facing away from the piezoelectric substrate.

[0007] Optionally, at least one of the first cavities extends through the intermediate busbar along the direction from the first interdigital transducer to the piezoelectric substrate.

[0008] Optionally, the conductive structure includes multiple substructures, and at least one of the substructures is provided within at least one of the first cavities.

[0009] Optionally, at least one of the substructures is spaced apart from the intermediate busbar.

[0010] Optionally, at least one of the substructures is connected to the intermediate busbar, and the substructure connected to the intermediate busbar is made of a different material than the intermediate busbar.

[0011] Optionally, there are multiple first cavities, including a first cavity group and a second cavity group, each of which includes at least one first cavity; the first cavity group and the second cavity group are spaced apart along a first direction.

[0012] Optionally, the first interdigital transducer further includes a first busbar, a first finger bar connected to the first busbar, and a second finger bar connected to the intermediate busbar; the second interdigital transducer further includes a second busbar, a third finger bar connected to the second busbar, and a fourth finger bar connected to the intermediate busbar; the first busbar, the intermediate busbar, and the second busbar are sequentially spaced apart in a first direction, the first finger bar and the second finger bar are sequentially spaced apart between the first busbar and the intermediate busbar, and the third finger bar and the fourth finger bar are sequentially spaced apart between the first busbar and the intermediate busbar.

[0013] Optionally, in the direction of sound wave propagation, the area where the first and second finger strips overlap is a first overlapping area, and the area where the third and fourth finger strips overlap is a second overlapping area; the cascaded resonator further includes a low-velocity structure, and at least one of the edges of the first and second overlapping areas is provided with the low-velocity structure.

[0014] Optionally, the first interdigital transducer further includes a third busbar and a first connecting finger; the third busbar is disposed on the side of the first busbar opposite to the intermediate busbar; the third busbar and the first busbar are spaced apart and connected by the first connecting finger; the second interdigital transducer further includes a fourth busbar and a second connecting finger; the fourth busbar is disposed on the side of the second busbar opposite to the intermediate busbar; the fourth busbar and the second busbar are spaced apart and connected by the second connecting finger.

[0015] Optionally, the first busbar is provided with at least one second cavity, which extends through the first busbar along the direction from the first interdigital transducer to the piezoelectric substrate; at least one second cavity is spaced apart along the direction of sound wave propagation.

[0016] The second busbar is provided with at least one third cavity, which extends through the second busbar along the direction from the first interdigital transducer to the piezoelectric substrate; at least one of the third cavities is spaced apart along the direction of sound wave propagation.

[0017] To address the aforementioned problems, embodiments of the present invention provide a filter comprising any of the cascaded resonators described above.

[0018] To address the aforementioned problems, embodiments of the present invention provide a radio frequency front-end module, including any of the cascaded resonators described above.

[0019] In the cascaded resonator, filter, and RF front-end module provided in this embodiment of the invention, since the conductive structure is asymmetrical relative to the middle surface, the entire cascaded resonator is also asymmetrical relative to the middle surface. This changes the transmission characteristics of the cascaded resonator, causing the frequencies of the transverse modes of the two cascaded resonators to be staggered, avoiding transverse mode resonance, and thus reducing the adverse effects caused by transverse mode superposition. Furthermore, by setting the conductive structure, the metal coverage of the junction area (i.e., the area where the middle busbar is located) of the two cascaded resonators can be increased, thereby reducing the resistance of the junction area and resulting in less heat generation when high-power current flows. Therefore, the configuration in this embodiment can also improve the power capacity of the cascaded resonator. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 1 ;

[0021] Figure 2 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 2 ;

[0022] Figure 3 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 3 ;

[0023] Figure 4 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 4

[0024] Figure 5 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 5 ;

[0025] Figure 6 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 6 ;

[0026] Figure 7 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 7 ;

[0027] Figure 8 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 8 ;

[0028] Figure 9 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 9 ;

[0029] Figure 10 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 10 ;

[0030] Figure 11 This is a schematic diagram of a cascaded resonator provided in an embodiment of the present invention. Figure 10 one.

[0031] The reference numerals in the accompanying drawings are as follows:

[0032] 100, First interdigital transducer; 200, Second interdigital transducer; 300, Conductive structure; 400, Intermediate surface;

[0033] 1. Intermediate busbar; 11. First cavity; 12. First surface; 13. Second surface; 14. First cavity group; 15. Second cavity group;

[0034] 2. Substructure;

[0035] 3. First busbar; 31. Third busbar; 32. First connector;

[0036] 4. First finger;

[0037] 5. Second finger strip;

[0038] 6. Second bus bar; 61. Fourth bus bar; 62. Second connecting finger;

[0039] 7. Third finger;

[0040] 8. Fourth finger;

[0041] 9. Low-sound-speed structure. Detailed Implementation

[0042] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0043] like Figure 1As shown, in one embodiment, the cascaded resonator includes a piezoelectric substrate, a first interdigital transducer 100, a second interdigital transducer 200, and a conductive structure 300. The first interdigital transducer 100, the second interdigital transducer 200, and the conductive structure 300 are all disposed on the piezoelectric substrate. The first interdigital transducer 100 and the second interdigital transducer 200 share an intermediate busbar 1. The intermediate busbar 1 is provided with at least one first cavity 11, and the conductive structure 300 is disposed in at least one first cavity 11. The conductive structure 300 is asymmetrical with respect to the middle surface 400 of the intermediate busbar 1. Along a first direction, the intermediate busbar 1 includes a first surface 12 and a second surface 13 disposed opposite to each other, and the first surface 12 and the second surface 13 are symmetrical with respect to the middle surface 400. The first direction is parallel to the arrangement direction of the first interdigital transducer 100 and the second interdigital transducer 200.

[0044] Because the conductive structure 300 is asymmetrical with respect to the intermediate surface 400, the entire cascaded resonator is also asymmetrical with respect to the intermediate surface 400. This alters the transmission characteristics of the cascaded resonator, causing the frequencies of the transverse modes of the two identical cascaded resonators to be staggered, thus avoiding transverse mode resonance and reducing the adverse effects caused by transverse mode superposition. Furthermore, while this embodiment sets the frequencies of the transverse modes of the two cascaded resonators to be staggered, this arrangement does not affect the finger strips of the two resonators. Therefore, the distance between adjacent finger strips in each resonator remains unchanged, thus not affecting the frequency of the dominant mode and ensuring the reliability of the cascaded resonators. In addition, the conductive structure 300 not only avoids transverse mode resonance but also increases the metal coverage of the junction area (i.e., the area where the intermediate busbar 1 is located) of the two cascaded resonators. This reduces the resistance of the junction area, resulting in less heat generation when high-power current flows. Therefore, this embodiment also improves the power capacity of the cascaded resonator.

[0045] It should be understood that the first interdigital transducer 100 is part of the first resonator 101, and the second interdigital transducer 200 is part of the second resonator 201. Besides sharing the intermediate busbar 1, the first resonator 101 and the second resonator 201 also share a piezoelectric substrate. Furthermore, both the first resonator 101 and the second resonator 201 are surface acoustic wave resonators.

[0046] For intermediate busbar 1, it belongs to both the busbar of the first interdigital transducer 100 and the busbar of the second interdigital transducer 200.

[0047] Furthermore, the intermediate surface 400 is a symmetrical plane of the intermediate busbar 1. Specifically, when the first cavity 11 and the conductive structure 300 are not provided on the intermediate busbar 1, along the first direction, the intermediate busbar 1 is divided into two parts by the intermediate surface 400. These two parts are the first part and the second part, respectively, and the first part and the second part are symmetrically arranged with respect to the intermediate surface 400. In the first direction, the first surface 12 is the surface of the first part that faces away from the second part, that is, the first surface 12 can be regarded as the side of the intermediate busbar 1 facing the first busbar 3, and the second surface 13 is the surface of the second part that faces away from the first part. The second surface 13 can be regarded as the side of the intermediate busbar 1 facing the second busbar 6.

[0048] The first and second parts are symmetrically arranged with respect to the intermediate surface 400. This can be considered as a plane perpendicular to the intermediate surface 400 passing through the first and second parts, resulting in two planes that intersect the first and second parts respectively, and a certain straight line that intersects the intermediate surface 400. The two planes that intersect the first and second parts respectively are symmetrical with respect to the straight line.

[0049] Furthermore, the first surface 12 and the second surface 13 are symmetrical with respect to the intermediate surface 400, so the distance between the intermediate surface 400 and the first surface 12 is equal to the distance between the intermediate surface 400 and the second surface 13, and the intermediate surface 400 can be perpendicular to the first direction.

[0050] In one feasible embodiment, the first surface 12, the second surface 13, and the intermediate surface 400 are arranged in parallel. In this case, the first surface 12 and the second surface 13 are also planes, and all three planes are perpendicular to the first direction. In another feasible embodiment, the first surface 12 and the second surface 13 are not parallel, but are only symmetrical with respect to the intermediate surface 400. In this way, the first surface 12 and the second surface 13 can also be planes. In this case, the first surface 12, the second surface 13, and the intermediate surface 400 form straight lines on the cross-section of the intermediate busbar 1. Of course, in this way, the first surface 12 and the second surface 13 can also be irregular surfaces. For example, a part of the first surface 12 is a plane, and another part is an arc surface.

[0051] It should be noted that in some embodiments, the intermediate busbar 1 without the first cavity 11 and conductive structure 300 is made of a uniform material, which can be regarded as a cuboid or cube. The intermediate surface 400 is a plane that bisects the intermediate busbar 1 without the first cavity 11 and conductive structure 300 in the first direction. In this case, it can be regarded that, in the top view direction, that is, from the first interdigital transducer 100 to the piezoelectric substrate, the plane formed by the intermediate busbar 1 without the first cavity 11 and conductive structure 300 is bisected into two planes by the straight line corresponding to the intermediate surface 400, and these two planes are symmetrical with respect to the straight line corresponding to the intermediate surface 400.

[0052] For the conductive structure 300, the material of the conductive structure 300 can be either a metallic material or a non-metallic material. In one feasible embodiment, along the first direction, the conductive structure 300 is divided into two parts by the intermediate surface 400, defined as a third part and a fourth part, wherein the third part and the fourth part are asymmetrical with respect to the intermediate surface 400. In another feasible embodiment, along the first direction, the conductive structure 300 may be located only on one side of the intermediate surface 400; in this case, the conductive structure 300 is also an asymmetrical structure with respect to the intermediate surface 400.

[0053] The number of first cavities 11 can be one or more, where "more" means two or more, and the meaning of "more" is the same in all embodiments, and will not be repeated hereafter. When there is one first cavity 11, the first cavity 11 is provided with a conductive structure 300; when there are multiple first cavities 11, all first cavities 11 may be provided with a conductive structure 300, or only a portion of the first cavities 11 may be provided with a conductive structure 300.

[0054] In this embodiment, the finger strip period and metal duty cycle of the first interdigital transducer 100 and the second interdigital transducer 200 are the same, so the frequency and amplitude of the main mode are the same. In this embodiment, by setting the first cavity 11 and conductive structure 300 on the intermediate busbar 1, the asymmetry of the intermediate busbar 1 is maintained. This sets the boundary conditions of the first interdigital transducer and the second interdigital transducer at the finger strip end, that is, at the junction of the intermediate busbar region and the regions of the first interdigital transducer and the second interdigital transducer, to be different. As a result, the propagation characteristics of the sound wave at this point are also different. This allows the two cascaded resonators (i.e., the first interdigital transducer and the second interdigital transducer and the piezoelectric substrate of the corresponding region) to stagger other stray modes while maintaining the same main mode (a necessary condition for cascading resonators), thus preventing stray modes from resonating and improving the performance of the cascaded resonator structure.

[0055] In one embodiment, a first cavity 11 is disposed on the surface of the intermediate busbar 1 facing away from the piezoelectric substrate. The surface of the intermediate busbar 1 facing away from the piezoelectric substrate is defined as the upper surface of the intermediate busbar 1, and the surface of the intermediate busbar 1 close to the piezoelectric substrate is defined as the lower surface of the intermediate busbar 1. The first cavity 11 is disposed on the upper surface of the intermediate busbar 1, which can be regarded as a groove on the upper surface of the intermediate busbar 1, or a hole through the intermediate busbar 1 (i.e., through from the upper surface to the lower surface of the intermediate busbar 1). However, when the first cavity 11 is grooved on the upper surface of the intermediate busbar 1, the groove does not penetrate to the lower surface of the intermediate busbar 1.

[0056] In this embodiment, when there are multiple first cavities 11, all the first cavities 11 may be slotted on the upper surface of the intermediate busbar 1; all the first cavities 11 may be holes that penetrate the intermediate busbar 1; or some of the first cavities 11 may be slotted on the upper surface of the intermediate busbar 1 and other first cavities 11 may be holes that penetrate the intermediate busbar 1. The structure of the first cavities 11 is not specifically limited here.

[0057] In this embodiment, when the number of first cavities 11 is one, the first cavity 11 is a structure with a groove on the upper surface of the intermediate busbar 1 or a hole provided through the intermediate busbar 1.

[0058] In one embodiment, at least one first cavity 11 extends through the intermediate busbar 1 along the direction from the first interdigital transducer 100 to the piezoelectric substrate.

[0059] In this embodiment, when there are multiple first cavities 11, along the direction from the first interdigital transducer 100 to the piezoelectric substrate, all the first cavities 11 can penetrate the intermediate busbar 1, or only a portion of the first cavities 11 can penetrate the intermediate busbar 1. When a first cavity 11 penetrates the intermediate busbar 1, the first cavity 11 actually penetrates from the upper surface of the intermediate busbar 1 to the lower surface of the intermediate busbar 1. When a first cavity 11 does not penetrate the intermediate busbar 1, the first cavity 11 is actually disposed on the upper surface of the intermediate busbar 1 and does not penetrate to the lower surface of the intermediate busbar 1, which can be regarded as a slotted structure on the intermediate busbar 1.

[0060] For a first cavity 11, when the first cavity 11 passes through the intermediate busbar 1 along the direction from the first interdigital transducer 100 to the piezoelectric substrate, the conductive structure 300 disposed in the first cavity 11 may be in contact with the piezoelectric substrate and spaced apart from the inner surface of the first cavity 11; or, the conductive structure 300 disposed in the first cavity 11 may be in contact with the inner surface of the first cavity 11 and the conductive structure 300 may be spaced apart from the piezoelectric substrate by a certain distance; or, the conductive structure 300 disposed in the first cavity 11 may be in contact with both the piezoelectric substrate and the inner surface of the first cavity 11.

[0061] Specifically, for a first cavity 11, when the first cavity 11 is disposed on the upper surface of the intermediate busbar 1 and does not penetrate to the lower surface of the intermediate busbar 1, the conductive structure 300 disposed in the first cavity 11 may be in contact with the bottom surface of the first cavity 11 but not in contact with the inner surface of the first cavity 11; or, the conductive structure 300 disposed in the first cavity 11 may be in contact with the inner surface of the first cavity 11 and spaced a certain distance from the bottom surface of the first cavity 11; or, the conductive structure 300 disposed in the first cavity 11 may be in contact with both the bottom surface and the inner surface of the first cavity 11 simultaneously.

[0062] In one embodiment, the conductive structure 300 may be made of a single metal material or a composite or alloy of different metals. Optionally, the conductive structure 300 may be made of aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, or a composite or alloy of the above metals.

[0063] In one embodiment, the first cavity 11 can be a hole formed by penetrating from the upper surface of the intermediate busbar 1 to the lower surface of the intermediate busbar 1, or a groove structure opened from the upper surface of the intermediate busbar 1. It can be a regular three-dimensional body, such as a cuboid or a cube, or an irregular three-dimensional body. In this case, a cutting plane can be set, which is parallel to the plane where the piezoelectric substrate is located (i.e., perpendicular to the middle surface). The cross-section obtained by the cutting plane cutting the first cavity 11 is a closed shape. The closed shape can be a regular polygon, a circle, or an arc, etc., without specific limitations.

[0064] like Figure 1 As shown, in one embodiment, the conductive structure 300 includes a plurality of substructures 2, and at least one substructure 2 is disposed within at least one first cavity 11. The substructures 2 are spaced apart from each other. "The conductive structure 300 is disposed within at least one first cavity 11" can mean that at least one substructure 2 is disposed within at least one first cavity 11.

[0065] For a first cavity 11, when a conductive structure 300 is provided inside the first cavity 11, it actually means that a substructure 2 is provided inside the first cavity 11, and the number of substructures 2 provided inside the first cavity 11 can be one or more. In addition, when two first cavities 11 are provided with substructures 2, the number of substructures 2 provided in the two first cavities 11 can be the same or different.

[0066] When there is only one substructure 2 disposed within a first cavity 11, the substructure 2 can be symmetrical or asymmetrical with respect to the intermediate surface 400, provided that the conductive structure 300 is asymmetrical with respect to the intermediate surface 400. When there are multiple substructures 2 disposed within the first cavity 11, all substructures 2 within the first cavity 11 can be symmetrical with respect to the intermediate surface 400; or, when there are multiple substructures 2 disposed within the first cavity 11, all substructures 2 within the first cavity 11 can be asymmetrical with respect to the intermediate surface 400; or, when there are multiple substructures 2 disposed within the first cavity 11, only a portion of the substructures 2 within the first cavity 11 are symmetrical with respect to the intermediate surface 400, while the other portion are asymmetrical with respect to the intermediate surface 400, again provided that the conductive structure 300 is asymmetrical.

[0067] For a substructure 2, the substructure 2 can be configured in the following ways: Method 1: Along the first direction, the substructure 2 is divided into two parts by the intermediate surface 400, and these two parts are defined as the first sub-part and the second sub-part, respectively. The first sub-part and the second sub-part can be symmetrical with respect to the intermediate surface 400 (i.e., the substructure 2 is a symmetrical structure with respect to the intermediate surface 400) or asymmetrical (i.e., the substructure 2 is asymmetrical with respect to the intermediate surface 400); Method 2: Along the first direction, the substructure 2 is completely located on one side of the intermediate surface 400. In this case, the substructure 2 is also asymmetrical with respect to the intermediate surface 400.

[0068] When there are multiple substructures 2 in the first cavity 11, there may be a substructure group or no substructure group among the multiple substructures 2 in the first cavity 11. The substructure group includes two substructures 2, which are located on both sides of the intermediate surface 400 and are symmetrical with respect to the intermediate surface 400.

[0069] In addition, when the conductive structure 300 is asymmetrical relative to the intermediate surface 400, at least one substructure 2 is asymmetrical relative to the intermediate surface 400, and this substructure 2 does not form a substructure group with other substructures 2.

[0070] Furthermore, each substructure 2 included in the conductive structure 300 is located within a corresponding first cavity 11, meaning that for each substructure 2, there will be a first cavity 11 to accommodate the substructure 2.

[0071] In one embodiment, for a substructure 2, the material of the substructure 2 can be a single metal material or a composite or alloy of different metals. Optionally, the material of the substructure 2 can be one of aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, or a composite or alloy of the above metals. Furthermore, when the conductive structure 300 has multiple substructures 2, the material of each substructure 2 can be the same, or at least two substructures 2 can be made of different materials.

[0072] Furthermore, when a substructure 2 is formed by combining different materials, the substructure 2 may include two regions with different materials. For example, in the first direction, the substructure 2 may include two regions with different materials, one region being made of aluminum and the other region being made of copper.

[0073] like Figure 2 , Figure 4 as well as Figures 6 to 9 As shown, in one embodiment, at least one substructure 2 is spaced apart from the intermediate busbar 1. When a substructure 2 is spaced apart from the intermediate busbar 1, a first cavity 11 accommodating the substructure 2 extends through the intermediate busbar 1 along the direction from the first interdigital transducer 100 to the piezoelectric substrate, and the substructure 2 is disposed on the piezoelectric substrate and spaced apart from the sidewall of the first cavity 11 accommodating it.

[0074] It should be noted that in this embodiment... Figures 2 to 9 The diagram only illustrates some combinations of the first cavity 11 and its substructure 2. Other structures of cascaded resonators are not shown here; please refer to relevant diagrams. Figure 1 Or it could be the structure described in the text of the embodiment; no specific limitations are made here. Figures 2 to 9 The dashed lines shown can be considered as the dashed lines corresponding to the middle surface on this plane.

[0075] In addition, when a substructure 2 is spaced apart from the intermediate busbar 1, the materials of the substructure 2 and the intermediate busbar 1 can be the same or different.

[0076] like Figure 3 , Figure 5 as well as Figure 7As shown, in one embodiment, at least one substructure 2 is connected to the intermediate busbar 1, and the substructure 2 connected to the intermediate busbar 1 is made of a different material than the intermediate busbar 1. Specifically, when a substructure 2 is connected to the intermediate busbar 1, if the first cavity 11 accommodating the substructure 2 extends through the intermediate busbar 1 along the direction from the first interdigital transducer 100 to the piezoelectric substrate, then the substructure 2 is connected to the inner surface of the first cavity 11.

[0077] When a substructure 2 is connected to the intermediate busbar 1, if the first cavity 11 accommodating the substructure 2 is disposed on the upper surface of the intermediate busbar 1, and the first cavity 11 does not penetrate the intermediate busbar 1 along the direction from the first interdigital transducer 100 to the piezoelectric substrate, then the substructure 2 may only be connected to the inner side of the first cavity 11, or the substructure 2 may only be connected to the bottom surface of the first cavity 11, or the substructure 2 may simultaneously connect the inner side of the first cavity 11 and the bottom surface of the first cavity 11.

[0078] In this embodiment, when a substructure in a first cavity 11 is connected to the intermediate busbar 1, the material of the substructure is different from the material of the intermediate busbar 1, or the material of the part of the substructure connected to the intermediate busbar 1 is different from the material of the intermediate busbar 1.

[0079] For a given first cavity 11, the substructures within the first cavity 11 can be spaced apart from the intermediate busbar 1, for example, refer to... Figure 3 , Figure 5 as well as Figure 7 A first cavity is provided within each substructure, which can be connected to the intermediate busbar 1, for example, as shown in the reference. Figure 6 Within a first cavity, a portion of each substructure 2 can be spaced apart from the intermediate busbar 1, while the other portion can be uniformly connected to the intermediate busbar 1, for example, as shown in the reference... Figure 4 and Figure 8 .

[0080] like Figure 10 As shown, in one embodiment, there are multiple first cavities 11, including a first cavity group 14 and a second cavity group 15. Each first cavity group 14 and each second cavity group 15 includes at least one first cavity 11. The first cavity groups 14 and 15 are spaced apart along a first direction. That is, along the first direction, the first cavities 11 are arranged in two rows. Each first cavity 11 in the first cavity group 14 belongs to the first row, and each first cavity 11 in the second cavity group 15 belongs to the second row. The first cavity group 14 is located between the second cavity group 15 and the first surface 12.

[0081] The number of first cavities 11 in the first cavity group 14 and the number of first cavities 11 in the second cavity group 15 can be the same or different.

[0082] Furthermore, each of the first cavities 11 within the first cavity group 14 may be without a substructure 2, or at least one of the first cavities 11 within the first cavity group 14 may contain at least one substructure 2. Similarly, each of the first cavities 11 within the second cavity group 15 may be without a substructure 2, or at least one of the first cavities 11 within the second cavity group 15 may contain at least one substructure 2. It should be noted that when none of the first cavities 11 within the first cavity group 14 contain a substructure 2, at least one of the first cavities 11 within the second cavity group 15 contains at least one substructure 2; and when none of the first cavities 11 within the second cavity group 15 contain a substructure 2, at least one of the first cavities 11 within the first cavity group 14 contains at least one substructure 2.

[0083] For each of the first cavities 11 in the same row, the sizes of any two first cavities 11 can be the same or different. Furthermore, the size of any first cavity 11 in the first cavity group 14 can be different from the size of any first cavity 11 in the second cavity group 15. The size of a first cavity 11 includes its length in the first direction and its width in the direction of sound wave propagation. When two first cavities 11 have different sizes, their lengths and widths are also different. The direction of sound wave propagation can be perpendicular to the first direction and parallel to the mid-plane.

[0084] In other embodiments, besides the first cavity group 14 and the second cavity group 15, there may be other numbers of cavity groups; the number of cavity groups is not specifically limited here. It should be noted that there is a partial area of ​​an intermediate busbar between two adjacent cavity groups. Specifically, this partial area refers to the absence of a first cavity structure and / or conductive structure in the partial area of ​​the intermediate busbar between two adjacent cavity groups in the first direction. Alternatively, in other embodiments, the plurality of first cavities 11 may be arranged in a row along the length of the intermediate busbar 1.

[0085] In one embodiment, the piezoelectric substrate can be made of materials with piezoelectric properties, such as lithium tantalate or lithium niobate; this embodiment is not limited to these materials. Furthermore, both the first interdigital transducer 100 and the second interdigital transducer 200 can be disposed on the upper surface of the piezoelectric substrate.

[0086] like Figure 1As shown, the first interdigital transducer 100 further includes a first busbar 3, a first finger bar 4 connected to the first busbar 3, and a second finger bar 5 connected to the intermediate busbar 1; the second interdigital transducer 200 includes a second busbar 6, a third finger bar 7 connected to the second busbar 6, and a fourth finger bar 8 connected to the intermediate busbar 1; the first busbar 3, the intermediate busbar 1, and the second busbar 6 are arranged sequentially at intervals in a first direction, the first finger bar 4 and the second finger bar 5 are arranged sequentially at intervals between the first busbar 3 and the intermediate busbar 1, and the third finger bar 7 and the fourth finger bar 8 are arranged sequentially at intervals between the second busbar 6 and the intermediate busbar 1.

[0087] In the first direction, the first finger bar 4 is spaced apart from the intermediate busbar 1, the second finger bar 5 is spaced apart from the first busbar 3, the third finger bar 7 is spaced apart from the intermediate busbar 1, and the fourth finger bar 8 is spaced apart from the second busbar 6. Furthermore, the first finger bar 4 and the second finger bar 5 are arranged along the length of the intermediate busbar 1, as are the third finger bar 7 and the fourth finger bar 8. Additionally, the second finger bar 5 may be connected to the first surface 12, and the fourth finger bar 8 may be connected to the second surface 13.

[0088] In one embodiment, the busbar and the finger strips can be prepared simultaneously in one process or in different processes; this embodiment does not impose specific limitations. Furthermore, the ends of each first finger strip 4 near the intermediate busbar 1 can be flush or not flush, and the ends of each second finger strip 5 near the first busbar 3 can be flush or not flush. The ends of each third finger strip 7 near the intermediate busbar 1 can be flush or not flush, and the ends of each fourth finger strip 8 near the second busbar 6 can be flush or not flush.

[0089] In one embodiment, the materials of the first busbar 3, the second busbar 6, the intermediate busbar 1, the first finger bar 4, the second finger bar 5, the third finger bar 7, and the fourth finger bar 8 can be a single metal material or a composite or alloy of different metals. Optionally, the materials of the first busbar 3, the second busbar 6, the intermediate busbar 1, the first finger bar 4, the second finger bar 5, the third finger bar 7, and the fourth finger bar 8 can be one of aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, or a composite or alloy of the above metals. In addition, these seven materials can be the same or different materials, which is not limited in this embodiment.

[0090] In one embodiment, the first busbar 3 can be an elongated structure, such as a cuboid, in which case its cross-sectional shape can be rectangular; the second busbar 6 can also be an elongated structure, such as a cuboid, in which case its cross-sectional shape can also be rectangular. Furthermore, the arrangement direction of the first busbar 3 and the second busbar 6 can be considered as a first direction.

[0091] like Figure 1 As shown, in one embodiment, in the direction of sound wave propagation, the area where the first finger strip 4 and the second finger strip 5 overlap is the first overlapping area 102, and the area where the third finger strip 7 and the fourth finger strip 8 overlap is the second overlapping area 202; the cascaded resonator also includes a low-velocity structure 9, and at least one of the edges of the first overlapping area 102 and the edges of the second overlapping area 202 is provided with a low-velocity structure 9.

[0092] The first overlapping region 102 is the operating region of the first resonator 101, and the second overlapping region 202 is the operating region of the second resonator 201. The low-velocity structure 9 reduces the propagation speed of sound waves, allowing for better confinement of acoustic energy in the operating region and resulting in fewer transverse modes. This suppresses transverse modes. Furthermore, the low-velocity structure 9 also reduces energy leakage in the operating region, improving the Q value of the cascaded resonator.

[0093] When the first overlapping region 102 is provided with a low-velocity structure 9, along the direction of sound wave propagation, the low-velocity structure 9 located in the first overlapping region 102 can be continuous or a multi-segment structure, with each segment spaced apart. When the second overlapping region 202 is provided with a low-velocity structure 9, along the direction of sound wave propagation, the low-velocity structure 9 located in the second overlapping region 202 can be continuous or a multi-segment structure, with each segment spaced apart.

[0094] The low-velocity structure 9 can be made of a single metal or a composite or alloy of different metals. Optionally, the low-velocity structure 9 can be made of molybdenum, tungsten, ruthenium, gold, magnesium, aluminum, copper, chromium, titanium, osmium, iridium, or a composite or alloy of the above metals. Of course, the low-velocity structure 9 can also be made of a dielectric material, such as tantalum oxide or silicon oxide.

[0095] In one feasible implementation, the low-velocity structure 9 can be disposed in the thickness direction of the finger strip, in which case the finger strip is essentially thickened. Specifically, the low-velocity structure 9 can be located above the finger strip, below the finger strip, or both above and below the finger strip. In another feasible implementation, the low-velocity structure 9 can also be disposed in the width direction of the finger strip, in which case the finger strip is essentially widened. Specifically, the low-velocity structure 9 can be located on one side of the finger strip in the width direction, or on both sides of the finger strip in the width direction. Furthermore, in other feasible implementations, the low-velocity structure 9 can also be disposed simultaneously in both the thickness and width directions of the finger strip, in which case the finger strip is essentially thickened and widened. In one feasible implementation, the low-velocity structure 9 can also be disposed in the dielectric layer of the corresponding region, thereby reducing the sound velocity in that region. Additionally, the low-velocity structure 9 can be in direct contact with the finger strip, or the low-velocity structure 9 and the finger strip can be separated by other membrane layers. The thickness direction of the finger strip can be the direction from the piezoelectric substrate to the first interdigital transducer 100.

[0096] When the low-speed sound structure 9 is disposed in the first overlapping region 102, the "finger strip" in the above three possible implementations includes the first finger strip 4 and the second finger strip 5; when the low-speed sound structure 9 is disposed in the second overlapping region 202, the "finger strip" in the above three possible implementations includes the third finger strip 7 and the fourth finger strip 8.

[0097] like Figure 10 As shown, in one embodiment, the first interdigital transducer 100 further includes a third busbar 31 and a first connecting finger 32; the third busbar 31 is disposed on the side of the first busbar 3 away from the intermediate busbar 1; the third busbar 31 and the first busbar 3 are spaced apart and connected by the first connecting finger 32; the second interdigital transducer 200 further includes a fourth busbar 61 and a second connecting finger 62; the fourth busbar 61 is disposed on the side of the second busbar 6 away from the intermediate busbar 1; the fourth busbar 61 and the second busbar 6 are spaced apart and connected by the second connecting finger 62. This arrangement also helps to suppress transverse morphology.

[0098] The first connecting finger 32 is disposed between the first busbar 3 and the third busbar 31. There can be multiple first connecting fingers 32. In this case, each first connecting finger 32 is disposed sequentially and at intervals between the first busbar 3 and the third busbar 31 along the direction of sound wave propagation.

[0099] The second connecting finger 62 is disposed between the second bus bar 6 and the fourth bus bar 61. There can be multiple second connecting fingers 62. In this case, each second connecting finger 62 is disposed sequentially and at intervals between the second bus bar 6 and the fourth bus bar 61 along the direction of sound wave propagation.

[0100] In one embodiment, the third busbar 31 can be a strip-shaped structure, such as a cuboid structure, and its cross-sectional shape can be rectangular; the fourth busbar 61 can also be a strip-shaped structure, such as a cuboid structure, and its cross-sectional shape can also be rectangular.

[0101] In this embodiment, by setting a third busbar 31 and a fourth busbar 61, and by setting a first cavity 11 on the intermediate busbar 1, when the intermediate busbar has only one set of cavities, referred to as the first cavity group 14, the intermediate busbar 1 can be regarded as being divided into a first busbar region and a second busbar region by the first cavity group 14, as can be referred to Figure 1 In this case, the middle busbar can be regarded as the inner busbar and outer busbar of one end of the first interdigital transducer 100, respectively, and the first busbar 3 and the third busbar 31 can be regarded as the inner busbar and outer busbar of the other end of the first interdigital transducer 100. Thus, the transverse mode suppression effect of the first resonator can be further improved through the first resonator with the inner busbar and outer busbar structure, thereby improving the performance of the cascaded resonator.

[0102] Similarly, for the second interdigital transducer 200, the first busbar region and the second busbar region are respectively used as the inner busbar and the outer busbar at one end of the second interdigital transducer 200, while the second busbar 6 and the fourth busbar 61 are used as the inner busbar and the outer busbar at the other end of the second interdigital transducer 200. Thus, by using the second resonator with the inner busbar and outer busbar structure, the transverse mode suppression effect of the second resonator can be further improved, thereby improving the performance of the cascaded resonator.

[0103] Of course, if there are multiple cavity groups, the busbar regions in the intermediate busbar can be divided by multiple cavity groups. There is a cavity group in an adjacent busbar region. The two busbar regions adjacent to the first interdigital transducer 100 in the intermediate busbar 1 are taken as the inner and outer busbars at one end of the first interdigital transducer 100. The two busbar regions adjacent to the second interdigital transducer 200 in the intermediate busbar 1 are taken as the inner and outer busbars at one end of the second interdigital transducer 200. This improves the transverse mode suppression effect of the first resonator and the second resonator, thereby improving the performance of the cascaded resonator.

[0104] In this embodiment, while improving the transverse mode suppression effect of the first and second resonators by setting the third busbar 31 and the fourth busbar 61, a conductive structure 300 is also set in the first cavity 11 of the intermediate busbar to increase the metal coverage of the intermediate busbar and reduce the resistance accordingly. This results in less heat generated when a high-power current flows through it, and also increases the power capacity. At the same time, the conductive structure is set asymmetrically to avoid transverse mode resonance, thereby reducing the impact of transverse mode superposition and improving the performance of the cascaded resonator.

[0105] like Figure 11 As shown, in one embodiment, the first busbar 3 is provided with at least one second cavity 33, which extends through the first busbar 3 along the direction from the first interdigital transducer 100 to the piezoelectric substrate; each second cavity 33 is spaced apart along the direction of sound wave propagation; wherein, a second cavity 33 may be formed by the first busbar 3, the third busbar 31 and two adjacent first connecting fingers 32.

[0106] In addition, in the direction of sound wave propagation, the outermost second cavity 33 can either extend to the end face of the first busbar 3 or not extend to the end face of the first busbar 3 in a direction away from the other second cavities.

[0107] The second busbar 6 is provided with at least one third cavity 63, which extends through the second busbar 6 along the direction from the first interdigital transducer 100 to the piezoelectric substrate; at least one third cavity 63 is spaced apart along the direction of sound wave propagation. One third cavity 63 may be formed by the aforementioned second busbar 6, the fourth busbar 61, and two adjacent second connecting fingers 62.

[0108] In addition, in the direction of sound wave propagation, the outermost third cavity 63 can either extend to one end face of the second busbar 6 or not extend to the end face of the second busbar 6 in the direction away from the other third cavities.

[0109] In this embodiment, at least one second cavity 33 is provided on the first busbar 3, and at least one third cavity 63 is provided on the second busbar 6. When a first cavity 11 is provided on the intermediate busbar 1, wherein the intermediate busbar has only one set of cavities, as can be referred to Figure 11 In the intermediate busbar, the first interdigital transducer 100 includes a first busbar 3 with at least one second cavity 33 and an intermediate busbar with a set of cavities. By setting openings on the two busbars of the first interdigital transducer 100, the transverse mode suppression effect of the first resonator can be further improved, thereby improving the performance of the cascaded resonator.

[0110] Similarly, for the second interdigital transducer 200, the second interdigital transducer 200 includes a first busbar 3 having at least one second cavity 33 and an intermediate busbar having a set of cavities. By setting openings on the two busbars of the second interdigital transducer 200, the transverse mode suppression effect of the second resonator can be further improved, thereby improving the performance of the cascaded resonator.

[0111] Of course, if there are multiple cavity groups, a cavity group adjacent to the first interdigital transducer 100 and two busbar regions adjacent to that cavity group can be regarded as a busbar on one side of the first interdigital transducer 100. In this case, openings are provided on the two busbars of the first interdigital transducer 100. Similarly, a cavity group adjacent to the second interdigital transducer 200 and two busbar regions adjacent to that cavity group can be regarded as a busbar on one side of the second interdigital transducer 200. In this case, openings are provided on the two busbars of the second interdigital transducer 200. This improves the transverse mode suppression effect of the first resonator and the second resonator, thereby improving the performance of the cascaded resonator.

[0112] In this embodiment, in addition to providing at least one second cavity 33 on the first busbar 3 and at least one third cavity 63 on the second busbar 6 to improve the transverse mode suppression effect of the first and second resonators, a conductive structure 300 is also provided in the first cavity 11 of the intermediate busbar to increase the metal coverage of the intermediate busbar and correspondingly reduce the resistance. This results in less heat generated when a high-power current flows through, and also increases the power capacity. At the same time, the conductive structure is asymmetrical to avoid transverse mode resonance, thereby reducing the impact of transverse mode superposition and improving the performance of the cascaded resonator.

[0113] Based on the above embodiments, the piezoelectric substrate in this embodiment can be a single-layer structure or a multi-layer structure. If it is a single-layer structure, the piezoelectric substrate can be a piezoelectric layer. If it is a multi-layer structure, the piezoelectric substrate includes at least a piezoelectric layer and a substrate. In some embodiments, a functional layer can also be provided between the piezoelectric layer and the substrate. Of course, in some embodiments, no functional layer may be provided between the piezoelectric layer and the substrate. The number of functional layers can be multiple or single, and can be limited according to the performance requirements of the cascaded resonator. No specific limitation is made here.

[0114] The present invention also provides a filter comprising the cascaded resonator described in any of the above embodiments.

[0115] This invention also provides a radio frequency (RF) front-end module, which includes the cascaded resonator described in any of the above embodiments. The RF front-end module may also include antennas, switches, power amplifiers, low-noise amplifiers, capacitors, inductors, and other devices, which will not be described in detail in the embodiments of this application. The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cascaded resonator, characterized in that, It includes a piezoelectric substrate, a first interdigital transducer, a second interdigital transducer, and a conductive structure; The first interdigital transducer, the second interdigital transducer, and the conductive structure are disposed on the piezoelectric substrate, and the first interdigital transducer and the second interdigital transducer share an intermediate busbar; The intermediate busbar is provided with at least one first cavity, and the conductive structure is disposed in at least one first cavity; The conductive structure is asymmetrical with respect to the middle surface of the intermediate busbar; Along the first direction, the intermediate busbar includes a first surface and a second surface disposed opposite to each other, the first surface and the second surface being symmetrical with respect to the intermediate surface; The first direction is parallel to the arrangement direction of the first interdigital transducer and the second interdigital transducer.

2. The cascaded resonator according to claim 1, characterized in that, The first cavity is disposed on the surface of the intermediate busbar that is away from the piezoelectric substrate.

3. The cascaded resonator according to claim 1, characterized in that, Along the direction from the first interdigital transducer to the piezoelectric substrate, at least one of the first cavities penetrates the intermediate busbar.

4. The cascaded resonator according to claim 1, characterized in that, The conductive structure includes multiple substructures, and at least one of the substructures is provided in at least one of the first cavities.

5. The cascaded resonator according to claim 4, characterized in that, At least one of the substructures is spaced apart from the intermediate busbar.

6. The cascaded resonator according to claim 4, characterized in that, At least one of the substructures is connected to the intermediate busbar, and the substructure connected to the intermediate busbar is made of a different material than the intermediate busbar.

7. The cascaded resonator according to claim 1, characterized in that, The number of the first cavity is multiple, and the multiple first cavities include a first cavity group and a second cavity group, and both the first cavity group and the second cavity group include at least one first cavity; The first cavity group and the second cavity group are spaced apart along a first direction.

8. The cascaded resonator according to any one of claims 1 to 7, characterized in that, The first interdigital transducer further includes a first busbar, a first finger bar connected to the first busbar, and a second finger bar connected to the intermediate busbar; The second interdigital transducer further includes a second busbar, a third finger bar connected to the second busbar, and a fourth finger bar connected to the intermediate busbar; The first busbar, the intermediate busbar, and the second busbar are arranged at intervals in the arrangement direction of the first interdigital transducer and the second interdigital transducer. The first finger bar and the second finger bar are arranged at intervals between the first busbar and the intermediate busbar. The third finger bar and the fourth finger bar are arranged at intervals between the first busbar and the intermediate busbar.

9. The cascaded resonator according to claim 8, characterized in that, In the direction of sound wave propagation, the area where the first finger strip and the second finger strip overlap is the first overlapping area, and the area where the third finger strip and the fourth finger strip overlap is the second overlapping area; The cascaded resonator further includes a low-velocity structure, and at least one of the edges of the first overlapping region and the second overlapping region is provided with the low-velocity structure.

10. The cascaded resonator according to claim 8, characterized in that, The first interdigital transducer further includes a third busbar and a first connecting finger; the third busbar is disposed on the side of the first busbar away from the intermediate busbar; the third busbar and the first busbar are spaced apart and connected by the first connecting finger; The second interdigital transducer further includes a fourth busbar and a second connecting finger; the fourth busbar is disposed on the side of the second busbar away from the intermediate busbar; the fourth busbar and the second busbar are spaced apart and connected by the second connecting finger.

11. The cascaded resonator according to claim 8, characterized in that, The first busbar is provided with at least one second cavity, which extends through the first busbar along the direction from the first interdigital transducer to the piezoelectric substrate; at least one second cavity is provided at intervals along the direction of sound wave propagation; The second busbar is provided with at least one third cavity, which extends through the second busbar along the direction from the first interdigital transducer to the piezoelectric substrate; at least one of the third cavities is spaced apart along the direction of sound wave propagation.

12. A filter, characterized in that, Includes the cascaded resonator as described in any one of claims 1-11.

13. A radio frequency front-end module, characterized in that, Includes the cascaded resonator as described in any one of claims 1-11.

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