Surface acoustic wave device and radio frequency front-end module

Abstract

The utility model discloses a surface acoustic wave device and a radio frequency front-end module. The surface acoustic wave device comprises an interdigital transducer, wherein the interdigital transducer comprises a first bus bar and a second bus bar which are oppositely arranged, an electrode finger and a plurality of gap electrodes; in the extending direction of the electrode fingers, an overlapping area is formed between the first bus bar and the second bus bar, a first area is formed between the overlapping area and the first bus bar, a second area is formed between the overlapping area and the second bus bar, and the first area and the second area are adjacent to the first bus bar and the second bus bar respectively; the plurality of gap electrodes are arranged in at least one of the first area and the second area, and the plurality of gap electrodes, the bus bars and the electrode fingers are arranged at intervals; wherein the plurality of gap electrodes form a first curve in the arrangement direction of the electrode fingers. According to the invention, the Q value near the anti-resonance point can be improved while the inhibition effect of the transverse mode is improved.

Description

Technical Field

[0001] This application relates to the field of radio frequency filtering technology, and in particular to a surface acoustic wave device and a radio frequency front-end module. Background Technology

[0002] Surface acoustic wave (SAW) devices, such as SAW resonators, are devices that convert electrical signals into acoustic signals or vice versa. SAW devices typically consist of a piezoelectric substrate and an interdigital transducer (IDT). The IDT is formed on the piezoelectric substrate and can be used to convert electrical signals into acoustic signals or vice versa.

[0003] Currently, the development of radio frequency technology has placed higher demands on the performance of surface acoustic wave (SAW) devices. Therefore, how to improve the quality factor (Bode Q) of SAW devices while ensuring the suppression effect of transverse modes has become an urgent problem to be solved. Utility Model Content

[0004] This application provides a surface acoustic wave device and an RF front-end module that can improve the suppression effect of transverse modes and also improve the Q value near the anti-resonance point.

[0005] In a first aspect, this application provides a surface acoustic wave device, which includes a piezoelectric substrate and an interdigital transducer disposed on the surface of the piezoelectric substrate. The interdigital transducer includes a first busbar and a second busbar disposed opposite to each other, electrode fingers and a plurality of gap electrodes.

[0006] Electrode fingers are disposed between the first busbar and the second busbar. Each electrode finger includes a plurality of first electrode fingers and a plurality of second electrode fingers. One end of each first electrode finger is electrically connected to the first busbar, and the other end of the first electrode finger is spaced apart from the second busbar. One end of each second electrode finger is electrically connected to the second busbar, and the other end of the second electrode finger is spaced apart from the first busbar. The plurality of first electrode fingers and the plurality of second electrode fingers are arranged alternately and at intervals. In the extension direction of the electrode fingers, there is an overlapping area between the first busbar and the second busbar. The overlapping area is the area where the first electrode fingers and the second electrode fingers overlap. The overlapping area includes a first area between the overlapping area and the first busbar, and the overlapping area includes a second area between the overlapping area and the second busbar. The first area and the second area are respectively adjacent to the first busbar and the second busbar.

[0007] The plurality of gap electrodes are disposed in at least one of the first region and the second region, and the plurality of gap electrodes are disposed at intervals from the first busbar, the second busbar and the electrode fingers;

[0008] The plurality of gap electrodes form a first curve in the arrangement direction of the electrode fingers.

[0009] Secondly, this application provides a radio frequency front-end module, including the surface acoustic wave device as described above.

[0010] The surface acoustic wave (SAW) device provided in this application includes a piezoelectric substrate and an interdigital transducer disposed on the surface of the piezoelectric substrate. The interdigital transducer includes a first busbar and a second busbar disposed opposite to each other, electrode fingers, and a plurality of gap electrodes. The electrode fingers are disposed between the first busbar and the second busbar, and include a plurality of first electrode fingers and a plurality of second electrode fingers. One end of the first electrode finger is electrically connected to the first busbar, and the other end of the first electrode finger is spaced apart from the second busbar. One end of the second electrode finger is electrically connected to the second busbar, and the other end of the second electrode finger is spaced apart from the first busbar. The plurality of first electrode fingers and the plurality of second electrode fingers intersect sequentially. The electrodes are arranged at intervals; in the extension direction of the electrode fingers, there is an overlapping region between the first busbar and the second busbar. The overlapping region is the area where the first electrode finger and the second electrode finger overlap each other. The overlapping region includes a first region between the first busbar and the first busbar, and the overlapping region includes a second region between the second busbar and the first busbar, respectively. The first region and the second region are adjacent to the first busbar and the second busbar, respectively. Multiple gap electrodes are disposed in at least one of the first region and the second region. The multiple gap electrodes are spaced apart from the first busbar, the second busbar, and the electrode fingers. The multiple gap electrodes form a first curve in the arrangement direction of the electrode fingers. By changing the position of the multiple gap electrodes, the multiple gap electrodes form a first curve in the arrangement direction of the electrode fingers. This not only disrupts the propagation continuity of the transverse mode and weakens the amplitude of the transverse mode, thereby effectively suppressing the transverse mode generated in the gap region (the region between the overlapping region and the busbar), but also improves the Q value of the surface acoustic wave device, especially the Q value at the anti-resonance point. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 These are curves showing the real part of the admittance and the Q value of a surface acoustic wave device, provided by related technologies.

[0013] Figure 2 This is a top view schematic diagram of a surface acoustic wave device provided in an embodiment of this application;

[0014] Figure 3 This is a top view schematic diagram of another surface acoustic wave device provided in the embodiments of this application;

[0015] Figure 4 This is a top view schematic diagram of another surface acoustic wave device provided in the embodiments of this application;

[0016] Figure 5(a) is a top view of another surface acoustic wave device provided in an embodiment of this application;

[0017] Figure 5(b) is a top view of another surface acoustic wave device provided in an embodiment of this application;

[0018] Figure 6(a) is a top view of another surface acoustic wave device provided in an embodiment of this application;

[0019] Figure 6(b) is a top view of another surface acoustic wave device provided in an embodiment of this application;

[0020] Figure 7(a) is a top view of another surface acoustic wave device provided in an embodiment of this application;

[0021] Figure 7(b) is a top view of another surface acoustic wave device provided in an embodiment of this application;

[0022] Figure 8 This is a top view schematic diagram of another surface acoustic wave device provided in the embodiments of this application;

[0023] Figure 9(a) is a top view of another surface acoustic wave device provided in an embodiment of this application;

[0024] Figure 9(b) is a top view of another surface acoustic wave device provided in an embodiment of this application;

[0025] Figure 10 This is a schematic diagram comparing the admittance amplitude variation curves of the surface acoustic wave device provided in the embodiments of this application and the surface acoustic wave device provided in Comparative Example 1;

[0026] Figure 11 This is a schematic diagram comparing the real part of the admittance of the surface acoustic wave device provided in the embodiments of this application with that of the surface acoustic wave device provided in Comparative Example 1;

[0027] Figure 12 This is a schematic diagram comparing the Q-value variation curves of the surface acoustic wave device provided in the embodiments of this application and the surface acoustic wave device provided in Comparative Example 1;

[0028] Figure 13 This is a schematic diagram comparing the passband insertion loss variation region lines of the filter provided in this embodiment and the filter provided in Comparative Example 2;

[0029] Figure 14 This is an enlarged comparison of the passband insertion loss variation region lines of the filter provided in this embodiment and the filter provided in Comparative Example 2. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0032] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0033] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0034] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0035] The following is a brief description of the implementation methods in the relevant technologies.

[0036] Piezoelectric thin film SAW devices are SAW devices that use piezoelectric thin films as piezoelectric functional materials. Their main advantages are their excellent temperature characteristics and high power tolerance. By bonding the piezoelectric layer and the substrate together, temperature changes are suppressed, and heat dissipation is improved, thereby achieving high power tolerance.

[0037] Because piezoelectric functional materials are multilayer composite materials, the propagation characteristics of sound waves within them differ from those of conventional surface acoustic wave (SAW) resonators. While conventional methods for suppressing transverse modes, such as piston or hammer structures, can suppress these modes, the sound wave energy leaking from the overlapping regions to the gap regions is re-excited in the gap regions, generating new modes. This manifests on the admittance curve as a new mode appearing near the anti-resonance point. The appearance of this mode leads to a severe deterioration of the Q-value near the anti-resonance point. Figure 1 As shown, the new noise mode will cause the Q value curve to dip, and the Q value at different frequency points will fluctuate greatly (around 400-1400). At the same time, the Q value at the anti-resonance point will deteriorate severely, and it will have a very bad impact on the performance of the filter, especially the passband insertion loss.

[0038] Therefore, this application provides a surface acoustic wave (SAW) device and a radio frequency (RF) front-end module. The SAW device includes a piezoelectric substrate and an interdigital transducer disposed on the surface of the piezoelectric substrate. The interdigital transducer includes a first busbar and a second busbar disposed opposite each other, electrode fingers, and a plurality of gap electrodes. The electrode fingers are disposed between the first busbar and the second busbar, and each electrode finger includes a plurality of first electrode fingers and a plurality of second electrode fingers. One end of each first electrode finger is electrically connected to the first busbar, and the other end of the first electrode finger is spaced apart from the second busbar. One end of each second electrode finger is electrically connected to the second busbar, and the other end of the second electrode finger is spaced apart from the first busbar. The plurality of first electrode fingers and the plurality of gap electrodes... The second electrode fingers are arranged alternately at intervals. In the extension direction of the electrode fingers, there is an overlapping region between the first busbar and the second busbar. The overlapping region is the area where the first electrode fingers and the second electrode fingers overlap. The overlapping region includes a first region between it and the first busbar, and a second region between it and the second busbar. The first and second regions are adjacent to the first and second busbars, respectively. Multiple gap electrodes are disposed in at least one of the first and second regions, and are spaced apart from the first busbar, the second busbar, and the electrode fingers. The multiple gap electrodes form a first curve in the arrangement direction of the electrode fingers. By changing the positions of the multiple gap electrodes, the multiple gap electrodes form a first curve in the arrangement direction of the electrode fingers. This not only disrupts the propagation continuity of the transverse modes and weakens the amplitude of the transverse modes, effectively suppressing the transverse modes generated in the gap region (the region between the overlapping region and the busbar), but also improves the Q value of the surface acoustic wave device, especially at the anti-resonance point. The surface acoustic wave device will be described in detail below.

[0039] It is understood that the surface acoustic wave device of this application can be a surface acoustic wave resonator, such as a general surface acoustic wave resonator, a temperature-compensated surface acoustic wave resonator, a surface acoustic wave resonator with a piezoelectric substrate including a multilayer thin film structure, a resonator structure with a cavity or groove on a piezoelectric substrate, or a longitudinally coupled resonator, a two-mode or multi-mode surface acoustic wave filter, or a trapezoidal filter or duplexer containing the above-mentioned surface acoustic wave resonators, etc. This application does not make any specific limitations.

[0040] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a surface acoustic wave device provided in an embodiment of this application.

[0041] like Figure 2 As shown, the surface acoustic wave device 100 includes a piezoelectric substrate 10 and an interdigital transducer 20 disposed on the surface of the piezoelectric substrate 10. The interdigital transducer 20 includes a first busbar 21 and a second busbar 22 disposed opposite to each other. Electrode fingers 23 are disposed between the first busbar 21 and the second busbar 22. The electrode fingers 23 include a plurality of first electrode fingers 231 and a plurality of second electrode fingers 232. One end of the first electrode finger 231 is electrically connected to the first busbar 21, and the other end of the first electrode finger 231 is spaced apart from the second busbar 22. One end of the second electrode finger 232 is electrically connected to the second busbar 22. The other end of the electrode finger 232 is spaced apart from the first bus bar 21, and multiple first electrode fingers 231 and multiple second electrode fingers 232 are arranged alternately in sequence; in the extension direction of the electrode finger 23, there is an overlapping region A between the first bus bar 21 and the second bus bar 22. The overlapping region A is the region where the first electrode fingers 231 and the second electrode fingers 232 overlap each other. The overlapping region A and the first bus bar 21 include a first region B1, and the overlapping region A and the second bus bar 22 include a second region B2. The first region B1 and the second region B2 are adjacent to the first bus bar 21 and the second bus bar 22, respectively.

[0042] The overlapping region A and the first busbar 21 include a first region B1 and a third region B3. The overlapping region A and the second busbar 22 include a second region B2 and a fourth region B4. The first region B1 and the second region B2 are adjacent to the first busbar 21 and the second busbar 22, respectively. The third region B3 is also adjacent to the first region B1 and the overlapping region A. The fourth region B4 is also adjacent to the second region B2 and the overlapping region A.

[0043] The interdigital transducer 20 includes a plurality of gap electrodes 24, which are disposed in at least one of the first region B1 and the second region B2. The plurality of gap electrodes 24 are spaced apart from the first busbar 21, the second busbar 22 and the electrode fingers 23. The plurality of gap electrodes 24 form a first curve in the arrangement direction of the electrode fingers 23.

[0044] For example, if multiple gap electrodes 24 are all disposed in the first region B1, and multiple gap electrodes 24 are all spaced apart from the first busbar 21 and the electrode fingers 23, in addition, multiple gap electrodes 24 form a first curve in the arrangement direction of the electrode fingers 23.

[0045] For example, if multiple gap electrodes 24 are all disposed in the second region B2, and multiple gap electrodes 24 are all spaced apart from the second busbar 22 and the electrode fingers 23, in addition, multiple gap electrodes 24 form a first curve in the arrangement direction of the electrode fingers 23.

[0046] For example, if multiple gap electrodes 24 are simultaneously disposed in the first region B1 and the second region B2, the multiple gap electrodes 24 in the first region B1 are all spaced apart from the first busbar 21 and the electrode fingers 23, and the multiple gap electrodes 24 in the second region B2 are all spaced apart from the second busbar 22 and the electrode fingers 23. The multiple gap electrodes 24 in the first region B1 form a first curve in the arrangement direction of the electrode fingers 23, and the multiple gap electrodes 24 in the second region B2 form a second curve in the arrangement direction of the electrode fingers 23.

[0047] It should be noted that the first curve can be formed by the first end (the end near the busbar) of the multiple gap electrodes 24 in the arrangement direction of the electrode fingers 23, or by the second end (the end near the overlapping region A) of the multiple gap electrodes 24 in the arrangement direction of the electrode fingers 23, or by the center point electrode fingers 23 of the multiple gap electrodes 24 in the arrangement direction of the electrode fingers 23, without any specific limitation here.

[0048] The surface acoustic wave device 100 provided in this application changes the positions of multiple gap electrodes 24, so that the multiple gap electrodes 24 are arranged in the first region B1 and / or the second region B2 and located on the acoustic propagation path of the transverse mode, and the multiple gap electrodes 24 form a first curve in the arrangement direction of the electrode fingers 23. Thus, without increasing the complexity of the process, it can not only disrupt the propagation continuity of the transverse mode and reduce the amplitude of the transverse mode, thereby effectively suppressing the high-frequency miscellaneous modes generated by secondary excitation in the gap region (the region between the overlapping region A and the busbar), but also improve the Q value of the surface acoustic wave device 100, especially the improvement effect on the Q value at the anti-resonance point is the most obvious.

[0049] In some embodiments, the piezoelectric substrate 10 includes a substrate and a piezoelectric layer stacked together.

[0050] The piezoelectric layer can be disposed on a substrate. The substrate can include single-crystal materials such as silicon and silicon carbide, and is not specifically limited thereto. The material of the piezoelectric layer can include at least one of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3).

[0051] For example, the interdigital transducer may also include a temperature compensation layer, which may be disposed between the substrate and the piezoelectric layer, thereby improving the negative frequency temperature characteristics of the piezoelectric layer.

[0052] For example, the interdigital transducer may also include a charge compensation layer, which may be disposed between the substrate and the piezoelectric layer. This allows the charge of the piezoelectric layer to be balanced or compensated.

[0053] It should be noted that the substrate and the piezoelectric layer may be provided with only a temperature compensation layer or a charge compensation layer or other functional layer structures, or they may be provided with both temperature compensation layer and charge compensation layer or other functional layer structures. No specific limitation is made here.

[0054] In some embodiments, the plurality of gap electrodes 24 include a plurality of first gap electrodes 24 and a plurality of second gap electrodes 24. The plurality of first gap electrodes 24 are disposed in a first region B1 and spaced apart from the first busbar 21 and the electrode fingers 23. The plurality of second gap electrodes 24 are disposed in a second region B2 and spaced apart from the second busbar 22 and the electrode fingers 23. The plurality of first gap electrodes 24 form a first curve in the arrangement direction of the electrode fingers 23, and / or the plurality of second gap electrodes 24 form a second curve in the arrangement direction of the electrode fingers 23.

[0055] For example, a plurality of first gap electrodes 24 are disposed in the first region B1 and spaced apart from the first busbar 21 and the electrode fingers 23, and the plurality of first gap electrodes 24 form a first curve in the arrangement direction of the electrode fingers 23; a plurality of second gap electrodes 24 are disposed in the second region B2 and spaced apart from the second busbar 22 and the electrode fingers 23, and the plurality of second gap electrodes 24 form a straight line in the arrangement direction of the electrode fingers 23.

[0056] For example, a plurality of first gap electrodes 24 are disposed in the first region B1 and spaced apart from the first busbar 21 and the electrode fingers 23, and the plurality of first gap electrodes 24 form a straight line in the arrangement direction of the electrode fingers 23; a plurality of second gap electrodes 24 are disposed in the second region B2 and spaced apart from the second busbar 22 and the electrode fingers 23, and the plurality of second gap electrodes 24 form a second curve in the arrangement direction of the electrode fingers 23.

[0057] For example, a plurality of first gap electrodes 24 are disposed in a first region B1 and spaced apart from the first busbar 21 and the electrode fingers 23, and the plurality of first gap electrodes 24 form a first curve in the arrangement direction of the electrode fingers 23; a plurality of second gap electrodes 24 are disposed in a second region B2 and spaced apart from the second busbar 22 and the electrode fingers 23, and the plurality of second gap electrodes 24 form a second curve in the arrangement direction of the electrode fingers 23.

[0058] It should be noted that as long as the gap electrode 24 in at least one of the first region B1 and the second region B2 forms a curve in the arrangement direction of the electrode fingers 23, the propagation continuity of the transverse mode can be disrupted, the amplitude of the transverse mode can be weakened, thereby effectively suppressing the high-frequency miscellaneous modes generated by the secondary excitation of the gap region, and at the same time, it can also improve the Q value of the surface acoustic wave device 100, especially the improvement effect on the Q value at the anti-resonance point is the most obvious.

[0059] In some embodiments, at least one of the first curve and the second curve satisfies a first function, the expression of which is Y. A (x)=Y A1 (x)*Y A2 (x); where Y A2 (x) is a periodic function.

[0060] For example, Y A1 (x) can be a non-periodic function or a periodic function. Non-periodic functions can be functions such as constant K, linear functions, and exponential functions, while periodic functions can be functions such as trigonometric functions. Here, K is a constant.

[0061] For example, the functions satisfied by the first curve and the second curve can be the same or different, as long as at least one of the first curve and the second curve satisfies the first function; preferably, both the first curve and the second curve satisfy the first function, which is beneficial for sound wave energy confinement.

[0062] For example, the positions of the multiple gap electrodes 24 in the first region B1 can be controlled to make the first curve formed by the multiple gap electrodes 24 in the first region B1 satisfy the first function; or, the positions of the multiple gap electrodes 24 in the second region B2 can be controlled to make the second curve formed by the multiple gap electrodes 24 in the second region B2 satisfy the first function; or, the positions of the multiple gap electrodes 24 in the first region B1 and the second region B2 can be controlled to make both the first curve formed by the multiple gap electrodes 24 in the first region B1 and the second curve formed by the multiple gap electrodes 24 in the second region B2 satisfy the first function.

[0063] It should be noted that the functions satisfied by the first curve and the second curve can be the same or different. If the functions satisfied by the first curve and the second curve are the same, the periods of the functions corresponding to the first curve and the second curve can be the same or different, without specific restrictions here.

[0064] In some embodiments, both the first curve and the second curve satisfy the first function, and the phase difference between the function corresponding to the first curve and the function corresponding to the second curve is greater than or equal to 45° and less than or equal to 315°.

[0065] For example, by controlling the positions of multiple gap electrodes 24 within the first region B1 and the second region B2, both the first curve formed by the multiple gap electrodes 24 in the first region B1 and the second curve formed by the multiple gap electrodes 24 in the second region B2 can satisfy a first function. Simultaneously, the phase difference between the function corresponding to the first curve and the function corresponding to the second curve is greater than or equal to 45° and less than or equal to 315°. For instance, the phase difference between the function corresponding to the first curve and the function corresponding to the second curve can be 45°, 90°, 135°, 180°, 225°, 270°, or 315°. This further suppresses high-frequency noise modes and maximizes the Q value of the surface acoustic wave device 100, especially showing the most significant improvement in the Q value at the anti-resonance point.

[0066] In some embodiments, the width of the gap electrode 24 in the arrangement direction of the electrode fingers 23 is d1, and the width of the electrode fingers 23 in their arrangement direction is d2; wherein, d1 ≥ d2.

[0067] For example, the width d1 of the gap electrode 24 in the arrangement direction of the electrode fingers 23 can be equal to the width d2 of the electrode fingers 23 in the arrangement direction, i.e., d1 = d2; the width d1 of the gap electrode 24 in the arrangement direction of the electrode fingers 23 can also be 1.5 times the width d2 of the electrode fingers 23 in the arrangement direction, i.e., d1 = 1.5d2; in the embodiments of this application, it is sufficient to control d1 ≥ d2, thereby further suppressing high-frequency noise modes and further improving the Q value of the surface acoustic wave device 100, especially the improvement effect on the Q value at the anti-resonance point is most obvious.

[0068] It should be noted that the width d1 of each gap electrode 24 in the arrangement direction of the electrode fingers 23 may be the same or different, but the width d1 of each gap electrode 24 in the arrangement direction of the electrode fingers 23 is greater than the width d2 of the electrode fingers 23 in its arrangement direction. Preferably, the width d1 of each gap electrode 24 in the arrangement direction of the electrode fingers 23 is the same.

[0069] In some embodiments, the length of the gap electrode 24 in the extension direction of the electrode finger 23 is L1; wherein, 0.05λ≤L1≤0.5λ, and λ is the wavelength of the sound wave.

[0070] The length L1 of the gap electrode 24 in the extension direction of the electrode finger 23 can be 0.05λ, 0.1λ, 0.2λ, 0.3λ, 0.4λ and 0.5λ.

[0071] In this embodiment, controlling 0.05λ≤L1≤0.5λ is sufficient. This allows the length L1 of the gap electrode 24 in the extension direction of the electrode finger 23 to be controlled within a small range, thereby reducing the volume of the surface acoustic wave device 100. This enables better performance with a smaller area, further suppresses high-frequency noise modes, and further improves the Q value of the surface acoustic wave device 100, especially the improvement effect on the Q value at the anti-resonance point is most obvious.

[0072] It should be noted that the length L1 of each gap electrode 24 in the extension direction of the electrode finger 23 may be the same or different, but the length L1 of each gap electrode 24 in the extension direction of the electrode finger 23 shall satisfy 0.05λ≤L1≤0.5λ. Preferably, the length L1 of each gap electrode 24 in the extension direction of the electrode finger 23 is the same.

[0073] In some embodiments, the overlapping region A includes a middle region A1 and an edge region A2 located on both sides of the middle region A1 in the extension direction of the electrode fingers 23; the interdigital transducer 20 also includes a plurality of acoustic impedance adjustment structures 26, the acoustic impedance adjustment structures 26 are located in the edge region A2, and the acoustic impedance of the edge region A2 is less than that of the middle region A1.

[0074] The endpoint of the acoustic impedance adjustment structure 26 near the gap electrode 24 is used to form the edge of the overlapping region A, which can be a straight line or a curve.

[0075] Specifically, by setting the acoustic impedance adjustment structure 26 in the edge region A2, the acoustic impedance of the edge region A2 is less than that of the middle region A1, so that the propagation speed of the sound wave in the edge region A2 is less than that in the middle region A1. At the same time, it can effectively suppress the transverse mode generated in the gap region and improve the Q value of the surface acoustic wave device 100.

[0076] For example, the acoustic impedance adjustment structure 26 can be a transverse mode suppression structure, such as thickening the electrode finger 23 in the edge region A2 to form a spike thickening structure, widening the electrode finger 23 in the edge region A2, or widening the electrode finger 23 in the edge region A2 and thickening it at the widening position, or widening the electrode finger 23 in the edge region A2 with different widths to form a T-shaped spike structure, or widening a part of the same electrode finger 23 in the edge region A2 and thickening both the widened part and the unwidened part to form a T-shaped spike structure, without specific limitations.

[0077] For example, the acoustic impedance adjustment structure 26 can be disposed in the thickness direction of the electrode finger 23. In this manner, the electrode finger 23 is essentially thickened. Specifically, the acoustic impedance adjustment structure 26 can be located above the electrode finger 23, below the electrode finger 23, or both above and below the electrode finger 23. The width direction of the electrode finger 23 is perpendicular to the extension direction of the electrode finger 23.

[0078] For example, the acoustic impedance adjustment structure 26 can also be disposed in the width direction of the electrode finger 23. In this manner, the electrode finger 23 is effectively widened. Specifically, the acoustic impedance adjustment structure 26 can be located on one side of the electrode finger 23 in the width direction, or it can be located on both sides of the electrode finger 23 in the width direction. The width direction of the electrode finger 23 is perpendicular to the extension direction of the electrode finger 23.

[0079] by Figure 2 Taking the acoustic impedance adjustment structure 26 in the structure as an example, the acoustic impedance adjustment structure 26 is formed by widening and thickening the electrode finger 23 in the edge region A2. In this embodiment, the acoustic impedance adjustment structure 26 is simultaneously disposed in the thickness direction and the width direction of the electrode finger 23. In this way, the electrode finger 23 is equivalent to being widened and thickened at the widened position.

[0080] It should be noted that the acoustic impedance adjustment structure 26 can be in direct contact with the electrode finger 23, or the acoustic impedance adjustment structure 26 and the electrode finger 23 can be separated by other membrane layers. The membrane layer used to separate the acoustic impedance adjustment structure 26 and the electrode finger 23 can be at least one of a temperature compensation layer and a frequency modulation layer.

[0081] like Figure 2As shown, in some embodiments, the interdigital transducer 20 further includes an intermediate electrode 25; the intermediate electrode 25 is located between the overlapping region A and the first busbar 21, and along the extending direction of the intermediate electrode 25, the intermediate electrode 25 is connected to the first electrode finger 231, and the extending direction of the intermediate electrode 25 intersects with the extending direction of the electrode finger 23, forming a first region B1 between the intermediate electrode 25 and the first busbar 21; the intermediate electrode 25 is spaced apart from the gap electrode 24 disposed in the first region B1; and / or, the intermediate electrode 25 is located between the overlapping region A and the second busbar 22, and along the extending direction of the intermediate electrode 25, the intermediate electrode 25 is connected to the second electrode finger 232, and the extending direction of the intermediate electrode 25 intersects with the extending direction of the electrode finger 23, forming a second region B2 between the intermediate electrode 25 and the second busbar 22; the intermediate electrode 25 is spaced apart from the gap electrode 24 disposed in the second region B2.

[0082] For example, the intermediate electrode 25 can be disposed only between the overlapping region A and the first busbar 21. Along the extending direction of the intermediate electrode 25, the intermediate electrode 25 is connected to the first electrode finger 231, and the extending direction of the intermediate electrode 25 intersects with the extending direction of the electrode finger 23. A first region B1 is formed between the intermediate electrode 25 and the first busbar 21, and a third region B3 is formed between the intermediate electrode 25 and the overlapping region A. The intermediate electrode 25 is spaced apart from the gap electrode 24 disposed in the first region B1. This can suppress stray modes in the first region B1 and the third region B3 to a certain extent.

[0083] For example, the intermediate electrode 25 can be disposed only between the overlapping region A and the second busbar 22. Along the extending direction of the intermediate electrode 25, the intermediate electrode 25 is connected to the second electrode finger 232, and the extending direction of the intermediate electrode 25 intersects with the extending direction of the electrode finger 23. A second region B2 is formed between the intermediate electrode 25 and the second busbar 22, and a fourth region B4 is formed between the intermediate electrode 25 and the overlapping region A. The intermediate electrode 25 is spaced apart from the gap electrode 24 disposed in the second region B2. This can suppress stray modes in the second region B2 and the fourth region B4 to a certain extent.

[0084] For example, the intermediate electrode 25 can be disposed simultaneously between the overlapping region A and the first busbar 21 and between the overlapping region A and the second busbar 22. For the intermediate electrode 25 near the first busbar 21, along its extension direction, the intermediate electrode 25 is connected to the first electrode finger 231, and the extension direction of the intermediate electrode 25 intersects with the extension direction of the electrode finger 231. A first region B1 is formed between the intermediate electrode 25 and the first busbar 21, and a third region B3 is formed between the intermediate electrode 25 and the overlapping region A. The intermediate electrode 25 is spaced apart from the gap electrode 24 disposed in the first region B1. For the intermediate electrode 25 near the second busbar 22, along its extension direction, the intermediate electrode 25 is connected to the second electrode finger 232, and the extension direction of the intermediate electrode 25 intersects with the extension direction of the electrode finger 231. A second region B2 is formed between the intermediate electrode 25 and the second busbar 22, and a fourth region B4 is formed between the intermediate electrode 25 and the overlapping region A. The intermediate electrode 25 is spaced apart from the gap electrode 24 disposed in the second region B2. This can suppress, to a certain extent, the stray modes in the first region B1, the second region B2, the third region B3, and the fourth region B4.

[0085] Preferably, the extension direction of the intermediate electrode 25 can be set perpendicular or approximately perpendicular to the extension direction of the electrode finger 23.

[0086] like Figure 2 As shown, exemplarily, the intermediate electrode 25 is connected to at least two first electrode fingers 231, and / or, the intermediate electrode 25 is connected to at least two second electrode fingers 232.

[0087] In this embodiment, the first electrode finger 231 is connected to the first bus bar 21, and the second electrode finger 232 is connected to the second bus bar 22. When an intermediate electrode 25 is provided between the overlapping region A and the first bus bar 21, the intermediate electrode 25 can be connected to at least two first electrode fingers 231. When an intermediate electrode 25 is provided between the overlapping region A and the second bus bar 22, the intermediate electrode 25 can be connected to at least two second electrode fingers 232.

[0088] For example, when an intermediate electrode 25 is provided between the overlapping region A and the first busbar 21, the intermediate electrode 25 is connected to at least two first electrode fingers 231, thereby forming a first region B1 between the intermediate electrode 25 and the first busbar 21, and forming a third region B3 between the intermediate electrode 25 and the overlapping region A.

[0089] For example, when an intermediate electrode 25 is provided between the overlapping region A and the second busbar 22, the intermediate electrode 25 is connected to at least two second electrode fingers 232, thereby forming a second region B2 between the intermediate electrode 25 and the second busbar 22, and forming a fourth region B4 between the intermediate electrode 25 and the overlapping region A.

[0090] For example, the intermediate electrode 25 can be connected to two adjacent first electrode fingers 231, or it can be connected to multiple adjacent first electrode fingers 231, without any specific limitation.

[0091] It should be noted that the thickness of the intermediate electrode 25 and the electrode finger 23 is generally the same, that is, the intermediate electrode 25 and the electrode finger 23 are on the same plane.

[0092] like Figure 3 As shown, exemplarily, the interdigital transducer 20 further includes a connecting electrode 28; a first end of the connecting electrode 28 is connected to a first busbar 21, a second end of the connecting electrode 28 is connected to an intermediate electrode 25, and is spaced apart from a gap electrode 24 disposed in the first region B1; and / or, a first end of the connecting electrode 28 is connected to a second busbar 22, a second end of the connecting electrode 28 is connected to an intermediate electrode 25, and is spaced apart from a gap electrode 24 disposed in the second region B2. In this case, one intermediate electrode 25 is connected to one electrode finger.

[0093] In this embodiment, the first electrode finger 231 is connected to the first busbar 21 via the intermediate electrode 25 and the connecting electrode 28. The connecting electrode 28 and the first electrode finger 231 can be connected to both ends of the intermediate electrode 25 to form a bent finger structure, or they can be connected to the same end, or other connection methods are not limited in this application. The second electrode finger 232 is connected to the second busbar 22 via the intermediate electrode 25 and the connecting electrode 28. The connecting electrode 28 and the second electrode finger 232 can be connected to both ends of the intermediate electrode 25 to form a bent finger structure, or they can be connected to the same end, or other connection methods are not limited in this application. When an intermediate electrode 25 and a connecting electrode 28 are provided between the overlapping region A and the first busbar 21, the first end of the connecting electrode 28 is connected to the first busbar 21, the second end of the connecting electrode 28 is connected to the intermediate electrode 25, and is spaced apart from the gap electrode 24 provided in the first region B1. When an intermediate electrode 25 and a connecting electrode 28 are provided between the overlapping region A and the second busbar 22, the first end of the connecting electrode 28 is connected to the second busbar 22, the second end of the connecting electrode 28 is connected to the intermediate electrode 25, and is spaced apart from the gap electrode 24 provided in the second region B2.

[0094] For example, when an intermediate electrode 25 and a connecting electrode 28 are provided between the overlapping region A and the first busbar 21, the first end of the connecting electrode 28 is connected to the first busbar 21, the second end of the connecting electrode 28 is connected to one end of the intermediate electrode 25, and the other end of the intermediate electrode 25 is connected to the first electrode finger 231. The first electrode finger 231 and the connecting electrode 28 are spaced apart on opposite sides of the intermediate electrode 25 in the extending direction of the intermediate electrode 25. The connecting electrode 28 is also spaced apart from the second electrode finger 232 and the gap electrode 24. By providing the connecting electrode 28 and the intermediate electrode 25, the stray mode in the first region B1 can be suppressed to a certain extent.

[0095] For example, when an intermediate electrode 25 and a connecting electrode 28 are provided between the overlapping region A and the second busbar 22, the first end of the connecting electrode 28 is connected to the second busbar 22, the second end of the connecting electrode 28 is connected to one end of the intermediate electrode 25, and the other end of the intermediate electrode 25 is connected to the second electrode finger 232. The second electrode finger 232 and the connecting electrode 28 are spaced apart on opposite sides of the intermediate electrode 25 in the extending direction of the intermediate electrode 25. The connecting electrode 28 is also spaced apart from the first electrode finger 231 and the gap electrode 24. By providing the connecting electrode 28 and the intermediate electrode 25, the stray mode in the second region B2 can be suppressed to a certain extent.

[0096] like Figure 4 As shown, in some embodiments, the interdigital transducer 20 further includes a plurality of dummy fingers 27; the first end of the dummy finger 27 is connected to the first busbar 21, and the second end of the dummy finger 27 is spaced apart from the gap electrode 24 disposed in the first region B1; or, the first end of the dummy finger 27 is connected to the intermediate electrode 25 located between the overlapping region A and the first busbar 21; and / or, the first end of the dummy finger 27 is connected to the second busbar 22, and the second end of the dummy finger 27 is spaced apart from the gap electrode 24 disposed in the second region B2; or, the first end of the dummy finger 27 is connected to the intermediate electrode 25 located between the overlapping region A and the second busbar 22. By providing the dummy fingers 27, the Q value of the surface acoustic wave device 100 can be improved, energy leakage can be reduced, and the heterodyne suppression effect of the first region B1 can be further improved.

[0097] like Figure 4 As shown, exemplarily, when a dummy finger 27 is provided between the overlapping region A and the first busbar 21 and the intermediate electrode 25 is connected to at least two first electrode fingers 231, the first end of the dummy finger 27 is connected to the first busbar 21, and the second end of the dummy finger 27 is spaced apart from the gap electrode 24 provided in the first region B1.

[0098] For example, when a dummy finger 27 is provided between the overlapping region A and the first busbar 21, and an intermediate electrode 25 and a connecting electrode 28 are provided between the overlapping region A and the first busbar 21, the first end of the dummy finger 27 is connected to the intermediate electrode 25, and the second end of the dummy finger 27 can be spaced apart from the gap electrode 24 or spaced apart from the second electrode finger 232.

[0099] like Figure 4 As shown, exemplarily, when a dummy finger 27 is provided between the overlapping region A and the second busbar 22 and the intermediate electrode 25 is connected to at least two second electrode fingers 232, the first end of the dummy finger 27 is connected to the second busbar 22, and the second end of the dummy finger 27 is spaced apart from the gap electrode 24 provided in the second region B2.

[0100] For example, when a dummy finger 27 is provided between the overlapping region A and the second busbar 22, and an intermediate electrode 25 and a connecting electrode 28 are provided between the overlapping region A and the second busbar 22, the first end of the dummy finger 27 is connected to the intermediate electrode 25, and the second end of the dummy finger 27 can be spaced apart from the gap electrode 24 or spaced apart from the first electrode finger 231.

[0101] Referring to Figures 5-9, in some embodiments, between the overlapping region A and the first busbar 21 and / or between the overlapping region A and the second busbar 22, the surface acoustic wave device 100 further includes at least one of the following: the second ends of a plurality of pseudo-fingers 27 form a third curve in the arrangement direction of the electrode fingers 23; the intermediate electrode 25 forms a fourth curve in the arrangement direction of the electrode fingers 23; the first busbar 21 or the second busbar 22 forms a fifth curve near the edge of the overlapping region A; and the overlapping region A forms a sixth curve near the edge of the first busbar 21 or the second busbar 22.

[0102] Specifically, between the overlapping region A and the first busbar 21, the second ends of multiple dummy fingers 27 can form a third curve in the arrangement direction of the electrode fingers 23; the intermediate electrode 25 can form a fourth curve in the arrangement direction of the electrode fingers 23; the first busbar 21 can form a fifth curve near the edge of the overlapping region A; the overlapping region A can form a sixth curve near the edge of the first busbar 21; between the overlapping region A and the second busbar 22, the second ends of multiple dummy fingers 27 can also form a third curve in the arrangement direction of the electrode fingers 23; the intermediate electrode 25 can also form a fourth curve in the arrangement direction of the electrode fingers 23; the second busbar 22 can also form a fifth curve near the edge of the overlapping region A; the overlapping region A can also form a sixth curve near the edge of the second busbar 22.

[0103] As shown in Figures 5(a) and 5(b), for example, the second ends of a plurality of spur fingers 27 form a third curve in the arrangement direction of the electrode fingers 23. The third curve satisfies a third function. The third curve formed by the second ends of the plurality of spur fingers 27 satisfies the third function by controlling the length of each spur finger 27 in the extension direction of the electrode fingers 23.

[0104] It should be noted that the functions satisfied by the first curve and the third curve can be the same or different. If the functions satisfied by the first curve and the third curve are the same, the periods of the functions corresponding to the first curve and the third curve can be the same or different, without specific restrictions here.

[0105] For example, if the first curve and the third curve satisfy the same function and have the same period, the phase difference between the third function and the first function can be greater than or equal to 0° and less than or equal to 180°.

[0106] As shown in Figure 5(a), in this embodiment of the application, the first curve and the third curve satisfy the same function and have the same function period, and the phase difference between the third function and the first function is equal to 0°.

[0107] As shown in Figure 5(b), in this embodiment of the application, the first curve and the third curve satisfy the same function and have the same function period, and the phase difference between the third function and the first function is equal to 180°.

[0108] As shown in Figures 6(a) and 6(b), for example, the intermediate electrode 25 forms a fourth curve in the arrangement direction of the electrode fingers 23. The fourth curve satisfies a fourth function. The structure and shape of the intermediate electrode 25 can be controlled so that the fourth curve formed by the intermediate electrode 25 in the arrangement direction of the electrode fingers 23 satisfies the fourth function.

[0109] It should be noted that the functions satisfied by the first curve and the fourth curve can be the same or different. If the functions satisfied by the first curve and the fourth curve are the same, the periods of the functions corresponding to the first curve and the fourth curve can be the same or different, without specific restrictions here.

[0110] For example, if the first curve and the fourth curve satisfy the same function and have the same period, the fourth function can have a phase difference with the first function greater than or equal to 0° and less than or equal to 180°.

[0111] As shown in Figure 6(a), in this embodiment of the application, the first curve and the fourth curve satisfy the same function and have the same function period, and the phase difference between the fourth function and the first function is equal to 0°.

[0112] As shown in Figure 6(b), in this embodiment of the application, the first curve and the fourth curve satisfy the same function and have the same function period, and the phase difference between the fourth function and the first function is equal to 180°.

[0113] As shown in Figures 7(a) and 7(b), for example, the first busbar 21 or the second busbar 22 forms a fifth curve near the edge of the overlapping region A. The fifth curve satisfies the fifth function. The fifth curve formed by the first busbar 21 or the second busbar 22 near the edge of the overlapping region A can be made to satisfy the fifth function by controlling the structure and shape of the first busbar 21 and the second busbar 22.

[0114] It should be noted that the functions satisfied by the first curve and the fifth curve can be the same or different. If the functions satisfied by the first curve and the fifth curve are the same, the periods of the functions corresponding to the first curve and the fifth curve can be the same or different, without specific restrictions here.

[0115] For example, if the first curve and the fifth curve satisfy the same function and have the same period, the phase difference between the fifth function and the first function can be greater than or equal to 0° and less than or equal to 180°.

[0116] As shown in Figure 7(a), in this embodiment of the application, the first curve and the sixth curve satisfy the same function and have the same function period, and the phase difference between the sixth function and the first function is equal to 0°.

[0117] As shown in Figure 7(b), in this embodiment of the application, the first curve and the sixth curve satisfy the same function and have the same function period, and the phase difference between the fifth function and the first function is equal to 180°.

[0118] like Figure 8 As shown, preferably, in the embodiments of this application, the first curve, the fourth curve and the fifth curve satisfy the same function and have the same function period, and the phase difference between the fourth function, the fifth function and the first function is equal to 0°, thereby further suppressing high-frequency noise modes and maximizing the Q value of the surface acoustic wave device 100.

[0119] As shown in Figures 9(a) and 9(b), for example, the overlapping region A forms a sixth curve near the edge of the first busbar 21 or the second busbar 22. The sixth curve satisfies the sixth function. The sixth curve formed near the edge of the overlapping region A near the edge of the first busbar 21 or the second busbar 22 can satisfy the sixth function by controlling the length of the first electrode finger 231 and the second electrode finger 232 in the extension direction of the electrode finger 23.

[0120] It should be noted that the functions satisfied by the first curve and the sixth curve can be the same or different. If the functions satisfied by the first curve and the sixth curve are the same, the periods of the functions corresponding to the first curve and the sixth curve can be the same or different, without specific restrictions here.

[0121] For example, if the first curve and the sixth curve satisfy the same function and have the same period, the sixth function can have a phase difference with the first function greater than or equal to 0° and less than or equal to 180°.

[0122] As shown in Figure 9(a), in this embodiment of the application, the first curve and the sixth curve satisfy the same function and have the same function period, and the phase difference between the sixth function and the first function is equal to 0°.

[0123] As shown in Figure 9(b), in this embodiment of the application, the first curve and the sixth curve satisfy the same function and have the same function period, and the phase difference between the sixth function and the first function is equal to 180°.

[0124] In some embodiments, the length of the intermediate electrode 25 in the extension direction of the electrode finger 23 is L2; ​​wherein, 0.1λ≤L2≤0.5λ, and λ is the wavelength of the sound wave.

[0125] The length L2 of the intermediate electrode 25 in the extension direction of the electrode finger 23 can be 0.1λ, 0.2λ, 0.3λ, 0.4λ and 0.5λ.

[0126] For example, the length L2 of the intermediate electrode 25 in the extension direction of the electrode finger 23 can be 0.1λ, i.e., L2 = 0.1λ; the length L2 of the intermediate electrode 25 in the extension direction of the electrode finger 23 can also be 0.5λ, i.e., L2 = 0.5λ; the length L2 of the intermediate electrode 25 in the extension direction of the electrode finger 23 can also be 0.2λ, i.e., L2 = 0.2λ; in the embodiments of this application, it is sufficient to control 0.1λ≤L2≤0.5λ, thereby further suppressing high-frequency noise modes and further improving the Q value of the surface acoustic wave device 100.

[0127] In some embodiments, the length of the intermediate electrode 25 in the extension direction of the electrode finger 23 is L2; ​​wherein, 0.1λ≤L2≤0.5λ, and λ is the wavelength of the sound wave.

[0128] The length L2 of the intermediate electrode 25 in the extension direction of the electrode finger 23 can be 0.1λ, 0.2λ, 0.3λ, 0.4λ and 0.5λ.

[0129] For example, the length L2 of the intermediate electrode 25 in the extension direction of the electrode finger 23 can be 0.1λ, i.e., L2 = 0.1λ; the length L2 of the intermediate electrode 25 in the extension direction of the electrode finger 23 can also be 0.5λ, i.e., L2 = 0.5λ; the length L2 of the intermediate electrode 25 in the extension direction of the electrode finger 23 can also be 0.2λ, i.e., L2 = 0.2λ; in the embodiments of this application, it is sufficient to control 0.1λ≤L2≤0.5λ, thereby further suppressing high-frequency noise modes and further improving the Q value of the surface acoustic wave device 100.

[0130] In some embodiments, if the intermediate electrode 25 is located between the overlapping region A and the first busbar 21, a third region B3 is formed between the intermediate electrode 25 and the overlapping region A; if the intermediate electrode 25 is located between the overlapping region A and the second busbar 22, a fourth region B4 is formed between the intermediate electrode 25 and the overlapping region A. The lengths of the third region B3 and the fourth region B4 in the extension direction of the electrode finger 23 are L3; where 0.1λ≤L3≤0.5λ, and λ is the wavelength of the sound wave.

[0131] The lengths L3 of the third region B3 and the fourth region B4 in the extension direction of the electrode finger 23 can be 0.1λ, 0.2λ, 0.3λ, 0.4λ, and 0.5λ, respectively.

[0132] For example, the length L3 of the third region B3 and the fourth region B4 in the extension direction of the electrode finger 23 can be 0.1λ, i.e., L3 = 0.1λ; the length L3 of the third region B3 and the fourth region B4 in the extension direction of the electrode finger 23 can also be 0.5λ, i.e., L3 = 0.5λ; the length L3 of the third region B3 and the fourth region B4 in the extension direction of the electrode finger 23 can also be 0.3λ, i.e., L3 = 0.3λ; in the embodiments of this application, it is sufficient to control 0.1λ≤L3≤0.5λ, thereby further suppressing high-frequency noise modes and further improving the Q value of the surface acoustic wave device 100.

[0133] In some embodiments, the length of the first region B1 and the second region B2 in the extension direction of the electrode finger 23 is L4; wherein, 0.3λ≤L4≤3λ, and λ is the wavelength of the sound wave.

[0134] The length L4 of the first region B1 and the second region B2 in the extension direction of the electrode finger 23 can be 0.3λ, 1λ, 2λ, 2.5λ and 3λ.

[0135] For example, the length L4 of the first region B1 and the second region B2 in the extension direction of the electrode finger 23 can be 0.3λ, i.e., L4 = 0.3λ; the length L4 of the first region B1 and the second region B2 in the extension direction of the electrode finger 23 can also be 2λ, i.e., L4 = 2λ; the length L4 of the first region B1 and the second region B2 in the extension direction of the electrode finger 23 can also be 3λ, i.e., L4 = 3λ; in the embodiments of this application, it is sufficient to control 0.3λ≤L4≤3λ, thereby further suppressing high-frequency noise modes and further improving the Q value of the surface acoustic wave device 100.

[0136] The following simulation experiments will demonstrate the implementation of the embodiments of this application. Figure 2 The Q-value variation curves of the surface acoustic wave device 100 provided by Comparative Example 1 (where the gap electrode 24 forms a straight line in the arrangement direction of the electrode fingers 23) are compared.

[0137] like Figure 10 and Figure 11 As shown, for easier comparison, the curve of Comparative Example 1 is shifted down by 10dB for a more intuitive comparison. Simulation experiments show that, compared to the surface acoustic wave device 100 provided in Comparative Example 1, the surface acoustic wave device 100 provided in this application embodiment has basically the same mismode intensity as the surface acoustic wave device 100 provided in Comparative Example 1. However, especially in the frequency band corresponding to 1.82-1.88GHz, i.e., the frequency band near the anti-resonance point, it can be seen that the mismode intensity of the surface acoustic wave device 100 provided in this application is significantly weaker than that of the surface acoustic wave device 100 provided in Comparative Example 1. This shows that the surface acoustic wave device 100 provided in this application embodiment almost eliminates the ripples near the resonance point, that is, it can effectively suppress the transverse modes generated in the gap region (the region between the overlapping region A and the busbar). At the same time, the high-frequency mismode suppression effect at and near the anti-resonance point is better than that of the surface acoustic wave device 100 provided in Comparative Example 1.

[0138] Table 1

[0139] <![CDATA[Q r ]]> <![CDATA[Q a ]]> <![CDATA[Q max ]]> <![CDATA[K2]]> Examples of this application 1048.557 2722.560 3329 10.3％ Comparative Example 1 946.433 1753.352 2261 10.3％ Increase 102.124 969.208 1068 0

[0140] like Figure 12As shown in Table 1, it can be seen that in most frequency bands, the Q value of the surface acoustic wave device 100 provided in this application is greater than that of the surface acoustic wave device 100 provided in Comparative Example 1, especially near the anti-resonance point, where the increase in Q value is most significant. The Q value of the surface acoustic wave device 100 provided in this application is much greater than that of the surface acoustic wave device 100 provided in Comparative Example 1. In particular, in the frequency band corresponding to 1.82-1.88GHz, i.e., the frequency band near the anti-resonance point, it can be seen that the Q value of the surface acoustic wave device 100 provided in this application is significantly stronger than that of the surface acoustic wave device 100 provided in Comparative Example 1. Therefore, it can be seen that the surface acoustic wave device 100 provided in this application embodiment can significantly improve the Q value compared to the surface acoustic wave device 100 provided in Comparative Example 1, while keeping the piezoelectric coupling factor almost unchanged, thereby improving the performance of the surface acoustic wave device 100.

[0141] In the case where the surface acoustic wave device 100 is a filter, the filter provided in the embodiments of this application will be described in detail below.

[0142] The filter includes multiple series-arm surface acoustic wave (SAW) devices 100 connected in series between the input and output terminals, and multiple parallel-arm SAW devices 100 connected at one end to the series-arm SAW device 100 and at the other end to the ground terminal. At least one of the series-arm and parallel-arm SAW devices 100 can be the SAW device 100 provided in any of the above embodiments. This filter can effectively suppress transverse modes generated in the gap region and improve the Q value of the SAW device 100, especially at the anti-resonance point where the improvement in Q value is most significant.

[0143] The following simulation experiments will demonstrate the implementation of the embodiments of this application. Figure 2 The passband insertion loss variation curves of the filter provided in Example 1 are compared with those of the filter provided in Comparative Example 2 (where the gap electrode 24 forms a straight line in the arrangement direction of the electrode fingers 23).

[0144] like Figure 13 and Figure 14 As shown in the simulation experiment, compared with the filter provided in Comparative Example 2, the filter provided in this application has a passband insertion loss that is basically the same as that provided in Comparative Example 2. Especially in the frequency band corresponding to 1.69-1.80GHz, it can be seen that the passband insertion loss of the filter provided in this application is significantly better than that of the filter provided in Comparative Example 2. It can be seen that the passband insertion loss of the filter provided in this application is improved by 0.1-0.15dB compared with the filter provided in Comparative Example 2.

[0145] This application also provides a radio frequency (RF) front-end module, which includes the surface acoustic wave (SAW) device 100 described in any of the above embodiments. This RF front-end module can effectively suppress transverse modes generated in the gap region and improve the Q value of the SAW device 100, especially at the anti-resonance point, thereby improving the reliability, safety, and practicality of the RF front-end module.

[0146] The radio frequency front-end module may include an antenna, a power amplifier, a low-noise amplifier, a switch, a filter, etc., without specific limitations.

[0147] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A surface acoustic wave device, characterized in that, The surface acoustic wave device includes a piezoelectric substrate and an interdigital transducer disposed on the surface of the piezoelectric substrate, wherein the interdigital transducer includes: The first bus bar and the second bus bar are set relative to each other; An electrode finger is disposed between the first busbar and the second busbar. The electrode finger includes a plurality of first electrode fingers and a plurality of second electrode fingers. One end of the first electrode finger is electrically connected to the first busbar, and the other end of the first electrode finger is spaced apart from the second busbar. One end of the second electrode finger is electrically connected to the second busbar, and the other end of the second electrode finger is spaced apart from the first busbar. The plurality of first electrode fingers and the plurality of second electrode fingers are arranged alternately and at intervals. In the extension direction of the electrode finger, there is an overlapping area between the first busbar and the second busbar. The overlapping area is the area where the first electrode finger and the second electrode finger overlap each other. The overlapping area includes a first area between the overlapping area and the first busbar, and the overlapping area includes a second area between the overlapping area and the second busbar. The first area and the second area are respectively adjacent to the first busbar and the second busbar. Multiple gap electrodes are disposed in at least one of the first region and the second region, and the multiple gap electrodes are evenly spaced from the first busbar, the second busbar and the electrode fingers; The plurality of gap electrodes form a first curve in the arrangement direction of the electrode fingers.

2. The surface acoustic wave device according to claim 1, characterized in that, The plurality of gap electrodes includes a plurality of first gap electrodes and a plurality of second gap electrodes. The plurality of first gap electrodes are disposed in the first region and spaced apart from the first busbar and the electrode fingers. The plurality of second gap electrodes are disposed in the second region and spaced apart from the second busbar and the electrode fingers. Wherein, the plurality of first gap electrodes form a first curve in the arrangement direction of the electrode fingers, and / or, the plurality of second gap electrodes form a second curve in the arrangement direction of the electrode fingers.

3. The surface acoustic wave device according to claim 2, characterized in that, At least one of the first curve and the second curve satisfies a first function, the expression of which is Y. A (x)=Y A1 (x)*Y A2 (x); Among them, Y A2 (x) is a periodic function.

4. The surface acoustic wave device according to claim 3, characterized in that, The phase difference between the first function corresponding to the first curve and the first function corresponding to the second curve is greater than or equal to 45° and less than or equal to 315°.

5. The surface acoustic wave device according to claim 1, characterized in that, The width of the gap electrode in the direction of the arrangement of the electrode fingers is d1, and the width of the electrode fingers in the direction of their arrangement is d2. Where d1≥d2.

6. The surface acoustic wave device according to claim 1, characterized in that, The length of the gap electrode in the extension direction of the electrode finger is L1; Where 0.05λ≤L1≤0.5λ, λ is the wavelength of the sound wave.

7. The surface acoustic wave device according to claim 1, characterized in that, The overlapping region includes a central region and edge regions located on both sides of the central region in the extension direction of the electrode finger; The interdigital transducer also includes multiple acoustic impedance adjustment structures located in the edge region, where the acoustic impedance is less than that in the middle region.

8. The surface acoustic wave device according to claim 1 or 2, characterized in that, The interdigital transducer also includes an intermediate electrode; The intermediate electrode is located between the overlapping region and the first busbar. Along the extension direction of the intermediate electrode, the intermediate electrode is connected to the first electrode finger, and the extension direction of the intermediate electrode intersects with the extension direction of the electrode finger. The intermediate electrode and the first busbar form the first region. The intermediate electrode and the gap electrode disposed in the first region are spaced apart. And / or, the intermediate electrode is located between the overlapping region and the second busbar, and along the extension direction of the intermediate electrode, the intermediate electrode is connected to the second electrode finger, and the extension direction of the intermediate electrode intersects with the extension direction of the electrode finger, and the second region is formed between the intermediate electrode and the second busbar; the intermediate electrode is spaced apart from the gap electrode disposed in the second region.

9. The surface acoustic wave device according to claim 8, characterized in that, The intermediate electrode is connected to at least two of the first electrode fingers, and / or the intermediate electrode is connected to at least two of the second electrode fingers.

10. The surface acoustic wave device according to claim 8, characterized in that, The interdigital transducer also includes connecting electrodes; The first end of the connecting electrode is connected to the first busbar, the second end of the connecting electrode is connected to the intermediate electrode, and is spaced apart from the gap electrode disposed in the first region; and / or, the first end of the connecting electrode is connected to the second busbar, the second end of the connecting electrode is connected to the intermediate electrode, and is spaced apart from the gap electrode disposed in the second region.

11. The surface acoustic wave device according to claim 8, characterized in that, The interdigital transducer also includes multiple pseudo-fingers; The first end of the prosthetic finger is connected to the first busbar, and the second end of the prosthetic finger is spaced apart from the gap electrode disposed in the first region; or, the first end of the prosthetic finger is connected to the intermediate electrode located between the overlapping region and the first busbar; and / or, The first end of the prosthetic finger is connected to the second busbar, and the second end of the prosthetic finger is spaced apart from the gap electrode disposed in the second region; or, the first end of the prosthetic finger is connected to the intermediate electrode located between the overlapping region and the second busbar.

12. The surface acoustic wave device according to claim 11, characterized in that, Between the overlapping region and the first busbar and / or between the overlapping region and the second busbar, the surface acoustic wave device further includes at least one of the following: The second ends of the plurality of prosthetic fingers form a third curve in the direction of the arrangement of the electrode fingers; The intermediate electrode forms a fourth curve in the direction of the arrangement of the electrode fingers; The first busbar or the second busbar forms a fifth curve near the edge of the overlapping area; The overlapping area forms a sixth curve near the edge of the first busbar or the second busbar.

13. The surface acoustic wave device according to claim 12, characterized in that, The first curve satisfies the first function, the third curve satisfies the third function, the fourth curve satisfies the fourth function, the fifth curve satisfies the fifth function, and the sixth curve satisfies the sixth function; Wherein, at least one of the third function, the fourth function, the fifth function, and the sixth function has a phase difference with the first function greater than or equal to 0° and less than or equal to 180°.

14. The surface acoustic wave device according to claim 13, characterized in that, The phase difference between at least one of the third function, the fourth function, the fifth function, and the sixth function and the first function is 0° or 180°.

15. The surface acoustic wave device according to claim 8, characterized in that, The length of the intermediate electrode in the extension direction of the electrode finger is L2; Where 0.1λ≤L2≤0.5λ, and λ is the wavelength of the sound wave.

16. The surface acoustic wave device according to claim 8, characterized in that, If the intermediate electrode is located between the overlapping region and the first busbar, a third region is formed between the intermediate electrode and the overlapping region. If the intermediate electrode is located between the overlapping region and the second busbar, a fourth region is formed between the intermediate electrode and the overlapping region. The length of the third region and the fourth region in the extension direction of the electrode finger is L3. Where 0.1λ≤L3≤0.5λ, λ is the wavelength of the sound wave.

17. The surface acoustic wave device according to claim 1, characterized in that, The length of the first region and the second region in the extension direction of the electrode finger is L4; Where 0.3λ≤L4≤3λ, λ is the wavelength of the sound wave.

18. The surface acoustic wave device according to claim 1, characterized in that, The piezoelectric substrate includes a substrate and a piezoelectric layer stacked together.

19. A radio frequency front-end module, characterized in that, Includes the surface acoustic wave device as described in any one of claims 1-18.

Images