Resonator, filter and radio frequency front-end module

Abstract

The invention relates to the technical field of radio frequency filtering, and discloses a resonator, a filter and a radio frequency front-end module, the resonator comprises a piezoelectric substrate and an interdigital transducer, and the interdigital transducer comprises an electrode finger strip and two bus bars; the plurality of first electrode fingers are respectively connected with the two bus bars, and the first electrode fingers are sequentially arranged at intervals in the first direction; the second electrode fingers are correspondingly connected with the first electrode fingers respectively and are arranged at intervals with the bus bars, and the second electrode fingers connected with the first electrode fingers are sequentially arranged at intervals in the first direction; the first finger width of the first electrode fingers is different from the second finger width of the second electrode fingers; a dividing line is correspondingly arranged between the first electrode finger and the second electrode finger, on the same side of the dividing line and in the first direction, the difference value of the first frequency F1 of the first electrode finger and the second frequency F2 of the second electrode finger is smaller than 0.01 Fr, and Fr is the main mode resonant frequency of the resonator. The invention aims to solve the technical problem that the performance of the resonator is deteriorated due to the fact that the resonator generates a transverse mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radio frequency filtering, in particular to a resonator, a filter and a radio frequency front-end module. BACKGROUND

[0002] A SAW (Surface Acoustic Wave) resonator is a kind of filter device made by using the piezoelectric effect and the physical characteristics of the surface acoustic wave propagation, and is widely used in various fields, such as the radio frequency field. The surface acoustic wave of the resonator is an elastic wave that concentrates energy near the surface. In the working process, the surface acoustic wave resonator will produce a transverse mode in addition to the main mode it needs, and the transverse mode will cause the performance of the surface acoustic wave resonator to deteriorate. SUMMARY

[0003] The present application aims to provide a resonator, a filter and a radio frequency front-end module to solve the technical problem that the surface acoustic wave resonator produces a transverse mode, causing the performance of the surface acoustic wave resonator to deteriorate.

[0004] The first aspect of the present application provides a resonator, comprising a piezoelectric substrate and an interdigital transducer, the interdigital transducer is arranged on the piezoelectric substrate, and the interdigital transducer comprises: two bus bars arranged opposite in a second direction; and electrode fingers, comprising a plurality of first electrode fingers and a plurality of second electrode fingers, the plurality of first electrode fingers are respectively connected to the two bus bars, and each first electrode finger is arranged in a first direction; each second electrode finger is respectively connected to each first electrode finger one by one, one end of the first electrode finger is connected to the bus bar, the other end of the first electrode finger is connected to the second electrode finger, and the second electrode finger is arranged spaced apart from the bus bar, and the second electrode fingers connected to each first electrode finger are arranged in the first direction; the first direction intersects the second direction, and the first direction is the propagation direction of the acoustic wave; wherein the first electrode finger has a first finger width, the second electrode finger has a second finger width, and the first finger width is different from the second finger width; the first electrode finger corresponds to a first frequency F1, the second electrode finger corresponds to a second frequency F2, and a dividing line corresponds to the first electrode finger and the second electrode finger, on the same side of the dividing line, the difference between the first frequency F1 and the second frequency F2 in the first direction is less than 0.01*Fr, and Fr is the main mode resonance frequency of the resonator.

[0005] The second aspect of the present application provides a resonator, comprising a piezoelectric substrate and an interdigital transducer, the interdigital transducer is arranged on the piezoelectric substrate, the interdigital transducer comprises: two bus bars arranged opposite in the second direction; and electrode fingers, comprising a plurality of first electrode fingers and a plurality of second electrode fingers, the plurality of first electrode fingers are respectively connected to the two bus bars, and each of the first electrode fingers is arranged in the first direction; each of the second electrode fingers is connected to each of the first electrode fingers one by one, one end of the first electrode finger is connected to the bus bar, the other end of the first electrode finger is connected to the second electrode finger, and the second electrode finger is arranged away from the bus bar, and the second electrode fingers connected to each of the first electrode fingers are arranged in the first direction; the first direction intersects the second direction, and the first direction is the propagation direction of the acoustic wave; wherein the first electrode finger has a first finger width, the second electrode finger has a second finger width, the first finger width is different from the second finger width; in the first direction, adjacent first electrode fingers and second electrode fingers form a group, the first electrode finger and the second electrode finger in the same group have a geometric center, each geometric center forms a division line, and the division line is not parallel to the bus bar.

[0006] The third aspect of the present application provides a filter, comprising the resonator.

[0007] The fourth aspect of the present application provides a radio frequency front end module, comprising the filter.

[0008] The present application provides a resonator, which has the following beneficial effects: The resonator of the present application alternately arranges the first electrode fingers on the two bus bars, each first electrode finger on each bus bar is connected to a second electrode finger, the finger width of the first electrode finger is different from that of the second electrode finger, thereby forming a sound velocity gradient between the second electrode finger and the first electrode finger, interfering with the propagation of the transverse mode, so that it is difficult to form stable resonance in the transverse area of the resonator, and the transverse mode resonance condition cannot be met, thereby suppressing the generation of the transverse mode.

[0009] Furthermore, on the same side of the division line between the first electrode finger and the second electrode finger, the resonant frequency deviation of the first electrode finger and the second electrode finger is limited to be less than 0.01*Fr, and after the plurality of first electrode fingers and the plurality of second electrode fingers are alternately arranged, the main mode resonant frequency of the resonator is still close to Fr, thereby avoiding affecting the main mode quality. The resonator of the present application can ensure the main mode quality is not affected on the basis of suppressing the transverse mode, and maximally suppresses the transverse mode. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1A cross-sectional view of a resonator according to an embodiment of the present application; Figure 2 A plan view of a resonator according to an embodiment of the present application; Figure 3 A plan view of a resonator according to an embodiment of the present application; Figure 4 A cross-sectional view of a resonator according to an embodiment of the present application; Figure 5 A cross-sectional view of a resonator according to an embodiment of the present application; Figure 6 A cross-sectional view of a resonator according to an embodiment of the present application; Figure 7 A plan view of a resonator according to an embodiment of the present application; Figure 8 A plan view of a resonator according to an embodiment of the present application; Figure 9 A plan view of a resonator according to an embodiment of the present application; Figure 10 A cross-sectional view of a resonator according to an embodiment of the present application; Figure 11a A plan view of an electrode finger according to an embodiment of the present application; Figure 11b A plan view of an electrode finger according to an embodiment of the present application; Figure 11c A plan view of an electrode finger according to an embodiment of the present application; Figure 12 A plan view of a resonator according to an embodiment of the present application; Figure 13 A plan view of a resonator according to an embodiment of the present application.

[0011] Reference signs in the drawings are as follows: 10 piezoelectric substrate; 20 interdigital transducer; 21 bus bar; 22 electrode finger; 221 first electrode finger; 222 second electrode finger; 223 division line; 223a first division line; 223b second division line; 224 finger end structure; 225 dummy finger structure; 226 third electrode finger; 30 reflective grid; 100 resonator; X first direction; Y second direction; Z third direction. DETAILED DESCRIPTION

[0012] The specific embodiments of the present application will be further described in conjunction with the drawings and examples. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application.

[0013] In the description of the present application, it should be noted that the positions or location relationships indicated by the terms "upper", "lower", "front", "back", "inner", "outer" and the like in the present application are based on the position relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as limiting the present application in indicating or implying that the devices and elements referred to must have a particular position, be constructed and operated in a particular position, and therefore cannot be understood as limiting the present application.

[0014] In the description of the present application, it should be understood that the terms "first", "second" and the like are used to describe various information in the present application, but these information should not be limited to these terms, and these terms are only used to distinguish the same type of information from each other. For example, the "first" information can also be referred to as "second" information, and similarly, the "second" information can also be referred to as "first" information without departing from the scope of the present application.

[0015] SAW (Surface Acoustic Wave) resonator is a short name of surface acoustic wave resonator, which is a filter device made by using piezoelectric effect and physical characteristics of surface acoustic wave propagation, and is widely used in various fields, such as radio frequency field. Among them, the surface acoustic wave is an elastic wave whose energy is concentrated near the surface.

[0016] Please refer to Figure 1 and Figure 2 , the surface acoustic wave resonator generally comprises a piezoelectric substrate 10 and an interdigital transducer 20 provided on the piezoelectric substrate 10, when a voltage signal is applied to the piezoelectric substrate 10, the interdigital transducer 20 excites acoustic waves in the piezoelectric material. Specifically, the interdigital transducer 20 comprises two bus bars 21 and a plurality of electrode fingers 22 connected to the two bus bars 21 respectively and arranged alternately along the propagation direction of the acoustic wave, the length of the projection of the plurality of electrode fingers 22 along the propagation direction of the acoustic wave overlaps, which is the aperture of the interdigital transducer 20, and the extension direction of the electrode fingers 22 is the aperture direction.

[0017] During the working process of the surface acoustic wave resonator, multiple modes of acoustic waves will be excited. Without considering the component of the acoustic wave vector in the third direction, if the acoustic wave only propagates along the first direction X and forms the maximum resonance strength, the mode of acoustic wave is identified as the main mode; if the acoustic wave propagates along the first direction X but forms a weaker resonance strength than the main mode, the mode of acoustic wave is identified as the secondary mode; if the propagation direction of the acoustic wave deviates from the first direction X, that is, the acoustic wave vector has a component in the second direction Y, at this time the acoustic wave will also form a regular and limited resonance in the second direction Y, and these acoustic wave modes become the transverse mode.

[0018] Therefore, the embodiment of the present application provides a resonator 100, which can realize suppression of a transverse mode.

[0019] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings. Figure 1 to Figure 1 1. Some embodiments of the present application are described in detail. In the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] In combination Figure 3 And Figure 4 The embodiment of the present application provides a resonator 100, which comprises a piezoelectric substrate 10 and an interdigital transducer 20, the interdigital transducer 20 is arranged on the piezoelectric substrate 10, the interdigital transducer 20 comprises electrode fingers 22 and two bus bars 21 arranged oppositely along a second direction Y, the electrode fingers 22 comprise a plurality of first electrode fingers 221 and a plurality of second electrode fingers 222, the plurality of first electrode fingers 221 are respectively connected to the two bus bars 21, and each first electrode finger 221 is arranged in sequence and spaced apart in a first direction X; each second electrode finger 222 is connected to each first electrode finger 221 in one-to-one correspondence, one end of the first electrode finger 221 is connected to the bus bar 21, the other end of the first electrode finger 221 is connected to the second electrode finger 222, and the second electrode finger 222 is arranged spaced apart from the bus bar 21, and the second electrode fingers 222 connected to each first electrode finger 221 are arranged in sequence and spaced apart in the first direction X; the first direction X intersects the second direction Y, and the first direction X is the propagation direction of the acoustic wave.

[0021] Among them, the first electrode finger 221 has a first finger width L1, and the second electrode finger 222 has a second finger width L2, the finger width is the width of the electrode finger in the first direction X; the corresponding resonant frequency of the first electrode finger 221 is the first frequency F1, and the corresponding resonant frequency of the second electrode finger 222 is the second frequency F2, and a dividing line 223 corresponding to the first electrode finger 221 and the second electrode finger 222 is arranged, on the same side of the dividing line 223, along the first direction X, the difference between the first frequency F1 and the second frequency F2 is less than 0.01*Fr, and Fr is the main mode resonant frequency of the resonator 100. Exemplarily, the difference between the first frequency F1 and the second frequency F2 can be less than 0.005*Fr, 0.006*Fr, 0.006*Fr, 0.007*Fr, 0.008*Fr or 0.009*Fr, etc.

[0022] In the embodiment, the first direction X intersects the second direction Y, the first direction X can be perpendicular to the second direction Y or not, the second direction Y is the aperture direction of the electrode finger 22, which can be understood as the transverse mode forming direction, and the first direction X is the propagation direction of the acoustic wave, which can be understood as the main mode forming direction. The two bus bars 21 are oppositely arranged along the second direction Y and extend along the first direction X, the first electrode fingers 221 on the two bus bars 21 are alternately and spaced arranged, any two adjacent first electrode fingers 221 are respectively connected to different bus bars 21, the first electrode fingers 221 on each bus bar 21 are correspondingly connected to a second electrode finger 222, the second electrode finger 222 extends to the other bus bar 21 and has a space with the other bus bar 21, thereby forming a interdigital finger structure. It should be noted that the connection between the first electrode finger 221 and the second electrode finger 222 and the connection between the first electrode finger 221 and the bus bar 21 are electrical connections, that is, the electrode finger 22 and the bus bar 21 are electrically connected.

[0023] Referring to FIG. 1, Figure 2 , Figure 2 The interdigital transducer structure in the related art is shown in FIG. 1, the same electrode finger 22 is periodically arranged between the two bus bars 21, thereby forming a resonant cavity, the acoustic wave will have an aperture direction component during propagation along the propagation direction, at this time, the acoustic wave energy in the aperture direction is generated, and the resonator transverse region resonates, thereby forming a transverse mode, which causes the resonator performance to deteriorate. In the interdigital transducer structure in the related art, the main mode resonance frequency is defined as Fr, the main mode resonance frequency Fr is the frequency at which the resonator resonates in its main mode.

[0024] The resonator 100 proposed in the embodiments of the present application has the first electrode fingers 221 arranged alternately on the two bus bars 21, and a second electrode finger 222 arranged at one end of each first electrode finger 221 on each bus bar 21. When the first electrode fingers 221 and the second electrode fingers 222 are arranged, the first electrode fingers 221 and the second electrode fingers 222 are arranged to have different finger widths. By changing the finger width of the electrode finger strips 22, a sound velocity gradient is formed between the second electrode fingers 222 and the first electrode fingers 221, and the effective size of the transverse space at different positions is destroyed. The effective size can be defined as the product of the transverse sound velocity and the transverse size. If the transverse structure is not uniform, the effective size is calculated by integration, so it is difficult to form a stable resonance in the transverse area of the resonator, which cannot meet the conditions of transverse mode transverse resonance, thereby suppressing the generation of the transverse mode. In the embodiments of the present application, when the first electrode fingers 221 and the second electrode fingers 222 are arranged, the first electrode fingers 221 and the second electrode fingers 222 have different finger widths. For example, the width of the first electrode fingers 221 is greater than the width of the second electrode fingers 222, or the width of the first electrode fingers 221 is less than the width of the second electrode fingers 222. Specifically, in the embodiments of the present application, the first finger width L1 is greater than the second finger width L2, and the finger width of the first electrode fingers 221 is greater than the finger width of the second electrode fingers 222, which are taken as examples for illustration, so that the finger width of the first electrode fingers 221 and the finger width of the second electrode fingers 222 are arranged to be different. In other embodiments, the finger width of the first electrode fingers 221 is less than the finger width of the second electrode fingers 222, and the finger width of the same electrode finger strip 22 can also be changed.

[0025] Please refer to Figure 5 In a resonator 100, the electrode finger strips 22 between the two bus bars 21 are all formed by the first electrode fingers 221, and the corresponding resonant frequency of the resonator formed by all the first electrode fingers 221 is the first frequency F1. Please refer to Figure 6 In a resonator 100, the electrode finger strips 22 between the two bus bars 21 are all formed by the second electrode fingers 222, and the corresponding resonant frequency of the resonator formed by all the first electrode fingers 221 is the second frequency F2.

[0026] Based on the above content, and in combination with the embodiments of the present application, on the same side of the split line 223, the resonant frequency corresponding to the resonator formed by all the first electrode fingers 221 is the first frequency F1, the resonant frequency corresponding to the resonator formed by all the second electrode fingers 222 is the second frequency F2, and the difference between the first frequency F1 and the second frequency F2 is less than 0.01*Fr, that is, the resonant frequency deviation between the first electrode fingers 221 and the second electrode fingers 222 is less than 0.01*Fr. After the first electrode fingers 221 and the second electrode fingers 222 on the same side of the split line 223 are alternately arranged, the main mode resonant frequency of the resonator 100 is still close to Fr, thereby avoiding affecting the quality of the main mode. In the embodiments of the present application, the split line 223 can be set according to requirements, such as the split line in FIG. 2B, which is only an example and can also be other shapes or trajectories. At the same time, the same side of the split line 223 refers to the fingers in the area of the split line 223 connected to one of the bus bars 21 as the same side, or the fingers in the area of the split line 223 connected to the other bus bar 21 as the same side. Therefore, the resonator 100 provided in the embodiments of the present application can not only suppress the transverse mode but also ensure that the quality of the main mode is not affected, thereby maximizing the suppression of the transverse mode. Figure 3 Figure 3 The split line in FIG. 2B is only an example and can also be other shapes or trajectories. At the same time, the same side of the split line 223 refers to the fingers in the area of the split line 223 connected to one of the bus bars 21 as the same side, or the fingers in the area of the split line 223 connected to the other bus bar 21 as the same side. Therefore, the resonator 100 provided in the embodiments of the present application can not only suppress the transverse mode but also ensure that the quality of the main mode is not affected, thereby maximizing the suppression of the transverse mode.

[0027] In some embodiments, the first frequency F1 of the first electrode fingers 221 is Fr+a*△f, and the second frequency F2 of the second electrode fingers 222 is Fr-a*△f, where a can be any real number. In an embodiment, -1≤a≤1, that is, the value of a is between -1 and 1. Wherein, △f is the resonant frequency deviation between the first electrode fingers 221 and the second electrode fingers 222.

[0028] In some embodiments, -20MHz≤△f≤20MHz, that is, the value of △f is between -20MHz and 20MHz.

[0029] In a specific example, the first frequency F1 of the first electrode fingers 221 is Fr+0.5*△f, and the second frequency F2 of the second electrode fingers 222 is Fr-0.5*△f. When the frequency deviation △f is less than 0.01*Fr, specifically, f1=Fr+1MHz, F2=Fr-1MHz, within this frequency deviation range, the resonant frequency of the resonator 100 is very close to the main mode resonant frequency Fr. In another specific example, the first frequency F1 of the first electrode fingers 221 is Fr+0.25*△f, and the second frequency F2 of the second electrode fingers 222 is Fr-0.25*△f, so that the difference between the first frequency F1 and the second frequency F2 is △f.

[0030] In the above examples, the widths of the first electrode fingers 221 and the second electrode fingers 222 are designed according to actual application, and the sizes of the first frequency F1 and the second frequency F2 are adjusted, as long as the frequency deviation △f is less than 0.01*Fr, the quality of the main mode can be maximally ensured without being affected on the basis of suppressing the lateral mode.

[0031] In some embodiments, the first direction X is perpendicular to the second direction Y, the second direction Y is the extension direction of the electrode finger strips 22, and the first direction X is the propagation direction of the acoustic wave and the extension direction of the bus bars 21. Through the above layout, the mechanical stability and electrical stability of the interdigital transducer 20 are improved, and the performance of the resonator 100 is improved.

[0032] In some embodiments, the piezoelectric substrate 10 can be made of lithium niobate, lithium tantalate, or quartz, and other piezoelectric materials, so as to form a piezoelectric effect. When an electric field or mechanical stress is applied to the piezoelectric substrate 10, an electric charge distribution and mechanical deformation will be generated.

[0033] The interdigital transducer 20 is an important component of the resonator 100, and its function is to complete the conversion between electrical energy and mechanical energy, that is, to generate and detect acoustic surface waves. The structure of the interdigital transducer 20 is usually manufactured on the piezoelectric layer by using a photolithography-plating-stripping or plating-photolithography-etching process, or other process methods. Here, no limitation is made.

[0034] The working principle of the resonator 100 provided in the embodiment is as follows: when a voltage signal is applied to the piezoelectric substrate 10, the interdigital transducer 20 excites acoustic waves in the piezoelectric material. The changing voltage causes the piezoelectric substrate 10 to deform, thereby exciting acoustic surface waves, and generating and propagating acoustic surface waves on the surface of the piezoelectric substrate 10 by using the piezoelectric effect, so as to realize the processing and transmission of signals. More specifically, the electrode fingers of the interdigital transducer 20 are used to excite and detect acoustic surface waves on the surface of the piezoelectric substrate 10, so as to realize the mutual conversion between electrical signals and acoustic signals. The bus bars 21 of the interdigital transducer 20 are used to connect the electrode fingers and transmit electrical signals. For example, when a plurality of interdigital transducers 20 are arranged in the resonator 100, the bus bars 21 and the wires can be used to electrically connect different interdigital transducers 20.

[0035] In some embodiments, the piezoelectric substrate 10 can be a single-layer piezoelectric structure, that is, the piezoelectric substrate 10 is composed of one kind of piezoelectric material. Of course, in other embodiments, the piezoelectric substrate 10 can also be a multi-layer piezoelectric structure, which is composed of piezoelectric layers made of different materials or the same material but having different properties. These layers are stacked together in a specific way to achieve the required performance.

[0036] In some embodiments, the multi-layer piezoelectric structure includes a piezoelectric film and a substrate, the interdigital transducer 20 is arranged on the piezoelectric film, and the substrate is arranged on the side of the piezoelectric film opposite to the interdigital transducer 20. The piezoelectric film is the core part of the piezoelectric substrate 10 and is made of a piezoelectric material, such as a piezoelectric material mainly composed of lithium niobate, lithium tantalate or quartz. The piezoelectric film has good piezoelectric effect and can convert mechanical stress into an electric signal or convert an electric signal into mechanical stress. The substrate is a support layer of the piezoelectric film and mainly functions to provide mechanical support and protect the piezoelectric film, while ensuring that the piezoelectric film can be uniformly stressed when subjected to external force. In addition, the substrate and the piezoelectric film together form a specific acoustic structure, thereby optimizing the performance of the resonator 100.

[0037] For the convenience of the following description, a first direction X, a second direction Y and a third direction Z perpendicular to each other are predefined in the embodiments of the present application, and the three directions constitute a three-dimensional coordinate system. When the resonator 100 is horizontally placed, the third direction Z is the height direction or the vertical direction of the resonator 100.

[0038] Please refer to Figure 3 In some embodiments, when the first electrode fingers 221 and the second electrode fingers 222 are connected, the first electrode fingers 221 and the second electrode fingers 222 have different finger widths, so that a step is formed at the connection position of the two different electrode fingers, and the two sides of the step correspond to the different electrode fingers, respectively.

[0039] Since the step can obviously separate the two electrode fingers, the division line 223 in the embodiments of the present application can be set according to requirements when defining the division line 223. In an embodiment, a division point (not shown in the figure) is arbitrarily selected at the same position of the step of each electrode finger, and then the division points selected on different electrode fingers are sequentially connected to form the division line 223 in the present application. The above-mentioned division line 223 is only an example, and can also be set according to other ways introduced in the present application. For example, the connection position of each first electrode finger 221 and the corresponding second electrode finger 222 is not a geometrically meaningful connection line position, but can also include a certain area range on both sides of the connection line of the above-mentioned two electrode fingers, and the division point can be located at the connection line of the first electrode finger 221 and the second electrode finger 222 or in the area close to the connection line of the first electrode finger 221 or the second electrode finger 222.

[0040] The division line 223 formed by different ways is within the protection scope of the present application, and will not be described here. For details, please refer to Figure 3 In an embodiment, the division line 223 is set as a curve, and specifically, the division line 223 is not parallel to the bus bar 21.

[0041] Please refer to Figure 2It should be understood that in the interdigital transducer 20, the main mode is formed when the acoustic wave propagates along the first direction X, and because the electrode fingers 22 are arranged according to the same rule, such as the same aperture, the same finger width, and the same period, the acoustic wave with a wave vector deviating from the first direction X has a component along the second direction Y, and the acoustic wave will resonate in the second direction. These resonance modes are transverse modes. Please refer to Figure 3 In the embodiment, the split line 223 is formed between the first electrode fingers 221 and the second electrode fingers 222, and the split line 223 is not parallel to the bus bars 21 on both sides or has an included angle with the bus bars 21. Along the first direction X, the effective aperture size is different at different positions. In the range where the split line 223 is close to the bus bars 21, the resonant cavity wall similar to the shape of the split line 223 can be formed, thereby destroying the parallel cavity walls on both sides of the resonant cavity and further destroying the condition of transverse resonance of the transverse mode, so as to achieve the effect of suppressing the transverse mode.

[0042] In some embodiments, the relative lengths of the first electrode fingers 221 and the second electrode fingers 222 are not specifically limited, and the lengths of the first electrode fingers 221 and the second electrode fingers 222 can be the same or different. The length of the first electrode finger 221 is greater than or less than the length of the second electrode finger 222. Please refer to Figure 3 Along the first direction X, the projections of part of the first electrode fingers 221 and the second electrode fingers 222 overlap.

[0043] Please refer to Figure 3 In some embodiments, the end of the second electrode finger 222 away from the first electrode finger 221 is defined as the finger end of the second electrode finger 222. The distance from the finger end of each second electrode finger 222 to the bus bar 21 opposite to it can be the same or different, and preferably the distances from the finger ends of all the second electrode fingers 222 to the bus bars 21 opposite to them are the same.

[0044] Please refer to Figure 7 In some embodiments, the end of the second electrode finger 222 away from the corresponding first electrode finger 221 is connected with a third electrode finger 226. The third electrode finger 226 is electrically connected with the second electrode finger 222 and is spaced apart from the bus bar 21. The finger width of the third electrode finger 226 is different from the finger width of the second electrode finger 222 and the finger width of the first electrode finger 221, Specifically, the embodiment increases the third electrode finger 226 on the basis of the first electrode finger 221 and the second electrode finger 222, the width of the third electrode finger 226 is greater or smaller than the width of the second electrode finger 222 and the first electrode finger 221, or the width of the third electrode finger 226 is between the width of the second electrode finger 222 and the first electrode finger 221, thereby forming a three-section electrode finger structure with different finger widths in the same electrode finger strip 22, further destroying the condition of resonance of the transverse mode, and enhancing the effect of suppressing the transverse mode.

[0045] Please refer to Figure 7 In some embodiments, when the third electrode finger 226 is connected with the second electrode finger 222, a step is formed at the connection position of the third electrode finger 226 and the second electrode finger 222 due to the different widths of the third electrode finger 226 and the second electrode finger 222. Thus, two steps are formed at the connection positions of the third electrode finger 226 and the second electrode finger 222 and the second electrode finger 222 and the first electrode finger 221 in the same electrode finger strip 22, and the two steps divide the three electrode fingers. When defining the division line 223 in the embodiment, the division line 223 can be set according to requirements. In an embodiment, the division points close to the same side bus bar 21 are connected in turn, thereby forming two spaced first division lines 223a and second division lines 223b between the two bus bars 21. In the area formed by the first division line 223a or the second division line 223b and the adjacent bus bar 21, there are both the first electrode finger 221 and the third electrode finger 226; in the area formed between the first division line 223a and the second division line 223b, there is only the second electrode finger 222, thereby forming three different areas between the two bus bars 21.

[0046] In some embodiments, the shapes or trajectories of the first division line 223a and the second division line 223b are the same, which is not specifically limited here. Preferably, the shapes or trajectories of the first division line 223a and the second division line 223b are the same, such as curves, so as to have the same sound speed effect in the same area and ensure the consistency of the sound speed in different areas.

[0047] In some embodiments, the third electrode finger 226 has a resonant frequency of a third frequency F3. In a resonator 100 in which the electrode finger strips 22 between the two bus bars 21 are all formed by the third electrode finger 226, the resonator 100 has a resonant frequency of the third frequency F3. In the same region, the frequency deviation of the first electrode finger 221, the second electrode finger 222 and the third electrode finger 226 is less than 0.01*Fr, so as to ensure that the main mode resonant frequency of the resonator 100 is still close to Fr, and avoid affecting the main mode quality, so as to maximize the suppression of the transverse mode while ensuring that the main mode quality is not affected.

[0048] In some embodiments, other electrode fingers can be connected at the end of the third electrode finger 226, so as to form multiple different electrode finger structures in the same electrode finger strip 22, and further form more division lines. The number of electrode fingers in the same electrode finger strip 22 is not limited here.

[0049] In some embodiments, the division line 223 includes any one of a curve, a polyline or a tooth-shaped line. The division line 223 can be a regular or irregular curve, a polyline or a tooth-shaped line. The positions of the division points are set according to the lengths of the first electrode finger 221 and the second electrode finger 222, so as to form different shapes of the division line 223, and different effective aperture sizes at different positions, so as to form a resonant cavity wall that is not parallel to the bus bar 21.

[0050] In some embodiments, the shape or trajectory of the division line 223 can also be set as a function line, such as a periodic function, a trigonometric function line, etc.

[0051] In some embodiments, referring to Figure 3 , the division line 223 is a curve, and at the peak position of the curve, the length of the first electrode finger 221 in the second direction Y is greater than the length of the second electrode finger 222.

[0052] The peak of the curve includes both the peak of the curve and the trough of the curve. The length of the first electrode finger 221 at the positions on both sides of the curve is less than the length of the first electrode finger 221 at the peak position of the curve. For example, at the peak position of the curve, the division point is located at the connection line of the first electrode finger 221 and the second electrode finger 222. From the direction of the peak of the curve to the positions on both sides, the division points of the first electrode finger 221 and the second electrode finger 222 gradually approach one bus bar 21 and gradually move away from the other bus bar 21. In this way, the first electrode finger 221 can be better matched with the curve, and the parallel cavity walls on both sides of the resonant cavity can be maximally destroyed, different effective aperture sizes are obtained at different positions, and the main mode quality is not affected on the basis of ensuring the resonant effect of the electrode finger on the sound wave, so as to maximize the suppression of the transverse mode.

[0053] In some embodiments, when the split line 223 is a curve as described above, the length of the second electrode finger 222 along the second direction Y is greater than the length of the first electrode finger 221 at the position of the curve valley. This arrangement can also make the second electrode finger 222 better correspond to the curve, maximally destroy the parallel cavity walls on both sides of the resonant cavity, and have different effective aperture sizes at different positions, while ensuring the resonant effect of the electrode fingers on the acoustic wave and maximizing the suppression of the transverse mode.

[0054] In some embodiments, referring to Figure 8 and Figure 9 , the split line 223 is a broken line or a toothed line so that the split line 223 is not parallel to the bus bar 21. The broken line or toothed line can be a regular or irregular track line as long as it is not parallel to the bus bar 21, so as to form non-parallel resonant cavity walls on both sides in the transverse mode direction and have different effective aperture sizes at different positions, thereby achieving the effect of suppressing the transverse mode. Of course, the split line 223 can also have other shapes or tracks, which are not specifically limited in the present embodiment. Regardless of whether the split line 223 is a broken line, a toothed line, or other shapes, on the same side of the split line 223, the resonant frequency deviation between the first electrode finger 221 and the second electrode finger 222 is ensured to be less than 0.01*Fr, and after the first electrode finger 221 and the second electrode finger 222 on the same side of the split line 223 are alternately arranged, the main mode resonant frequency of the resonator 100 is still close to Fr, thereby avoiding affecting the quality of the main mode.

[0055] Referring to Figure 3 , in some embodiments, the first electrode fingers 221 are equally spaced apart in the first direction X. In this way, in the first direction X, the main modes excited by adjacent first electrode fingers 221 have a constant phase difference in the propagation direction, and acoustic wave coherent superposition can be achieved, thereby enhancing the amplitude of the acoustic wave and improving the quality of the main mode and the performance of the resonator 100.

[0056] Referring to Figure 3 , in some embodiments, the second electrode fingers 222 are equally spaced apart in the first direction X. In this way, in the first direction X, the main modes excited by adjacent second electrode fingers 222 have a constant phase difference in the propagation direction, and acoustic wave coherent superposition can be achieved, thereby enhancing the amplitude of the acoustic wave and improving the quality of the main mode and the performance of the resonator 100.

[0057] Referring to Figure 4 and Figure 10 , in some embodiments, in the first direction X, the sum of the gap width on both sides of the first electrode finger 221 and the first finger width L1 is a first width P1, the sum of the gap width on both sides of the second electrode finger 222 and the second finger width L2 is a second width P2, and the first width P1 is the same as the second width P2.

[0058] Specifically, for the convenience of description, the following convention is made for the finger region P of the electrode finger 22: the finger region P is the sum of the width of the finger width of the electrode finger 22 and the gap on both sides of the finger region P, and the finger region P can reflect the size of the space occupied by each electrode finger 22 in the first direction X. Preferably, in a resonator, the gap on both sides of the electrode finger 22 is equal, the thickness of the electrode finger 22 is H, the bottom width of the electrode finger 22 is LW, the duty cycle DF is LW / P, and the gap width on both sides of the electrode finger 22 is LS = P*(1-DF) / 2.

[0059] In the present embodiment, the first width P1 is the finger region width of the first electrode finger 221, and the second width P2 is the finger region width of the second electrode finger 222. The finger region widths of the first electrode finger 221 and the second electrode finger 222 are the same, so that the duty cycle DF of each electrode finger 22 is the same, the acoustic wave energy is uniformly distributed along the propagation direction, the main mode frequency is highly consistent, local energy concentration or attenuation is avoided, and the main mode quality is further improved.

[0060] Please refer to Figure 11a In some embodiments, on the basis that the finger region widths of the first electrode finger 221 and the second electrode finger 222 are the same, the center line of the first electrode finger 221 is aligned with the center line of the second electrode finger 222 in the first direction X. In this way, the second electrode finger 222 is arranged centrally relative to the first electrode finger 221, which facilitates the processing of the electrode finger 22 and reduces the processing cost, and makes the electrode finger 22 more uniformly distributed as a whole and better symmetrical, thereby ensuring the suppression effect on the transverse mode.

[0061] In some embodiments, on the basis that the finger region widths of the first electrode finger 221 and the second electrode finger 222 are the same, one side of the first electrode finger 221 is aligned with one side of the second electrode finger 222 in the first direction X.

[0062] For example, as shown in Figure 11b , the left side of the first electrode finger 221 is aligned with the left side of the second electrode finger 222, and the right side of the first electrode finger 221 is not aligned with the right side of the second electrode finger 222 due to the larger finger width of the first electrode finger 221 than that of the second electrode finger 222.

[0063] For example, as shown in Figure 11c , the right side of the first electrode finger 221 is aligned with the right side of the second electrode finger 222, and the left side of the first electrode finger 221 is not aligned with the left side of the second electrode finger 222 due to the larger finger width of the first electrode finger 221 than that of the second electrode finger 222.

[0064] In other examples, the left side of the first electrode finger 221 is aligned with the right side of the second electrode finger 222, or the right side of the first electrode finger 221 is aligned with the left side of the second electrode finger 222, and the first electrode finger 221 and the second electrode finger 222 are electrically connected by point contact.

[0065] Referring to Figure 3 , Figure 8 or Figure 9 In some embodiments, the length of the first electrode finger 221 is different from the length of the second electrode finger 222 in the second direction Y, and the length of the first electrode finger 221 is greater than or less than the length of the second electrode finger 222, so that the division points of the first electrode finger 221 and the second electrode finger 222 in each electrode finger strip 22 are not on the same straight line, and the division points are sequentially connected to form a division line that is not flat on the bus bar 21. Therefore, by setting the first electrode finger 221 and the second electrode finger 222 with different lengths, the transverse mode resonance condition can be destroyed.

[0066] In some embodiments, the aperture of the first electrode finger 221 is the same as the aperture of the second electrode finger 222.

[0067] Specifically, the length of the projection of the electrode finger strip 22 in the sound wave propagation direction that overlaps is the aperture, and the aperture of the first electrode finger 221 is the same as the aperture of the second electrode finger 222, that is, the length of the projection of the first electrode finger 221 and the second electrode finger 222 in the first direction X that overlaps is the same, so that the apertures of all the electrode finger strips 22 in the sound wave propagation direction remain consistent, avoiding local energy attenuation due to aperture differences, controlling the sound pressure field amplitude fluctuation within a reasonable range, reducing nonlinear effects (such as harmonic distortion) and improving the main mode signal quality, thereby improving the energy concentration and frequency response stability of the resonator.

[0068] In some embodiments, the first frequency F1 of the first electrode finger 221 is the same as the second frequency F2 of the second electrode finger 222. Thus, the resonance frequency deviation of the first electrode finger 221 and the second electrode finger 222 is 0, the main mode resonance frequency of the resonator 100 is unchanged, and the main mode quality can be maximized to be unaffected.

[0069] Referring to Figure 12 In some embodiments, the second electrode finger 222 is provided with a finger end structure 224 at one end away from the first electrode finger 221, and the size of the finger end structure 224 in the first direction X is greater than or equal to the size of the second electrode finger 222, thereby forming a finger end widening structure at the end of the second electrode finger 222.

[0070] Referring to Figure 12In some embodiments, the size of the tip structure 224 in the third direction Z is greater than or equal to the size of the second electrode finger 222, thereby forming a tip thickening structure at the end of the second electrode finger 222. The two different tip structures 224 described above can be arranged according to requirements, and can be widened, thickened, or only widened or thickened, which are all within the protection scope of the present application.

[0071] In the above embodiments, the tip structure 224 is arranged at the end of the second electrode finger 222 to form a tip widening structure or a tip thickening structure, thereby increasing the mass load on the opposite sides of the second electrode finger 222 in the second direction Y, and enhancing the suppression of the transverse mode of the resonator 100. More specifically, the tip structure 224 changes the sound speed on the opposite sides in the second direction Y, thereby changing the reflection coefficient of the sound wave, which helps to further suppress the transverse mode and the spurious mode.

[0072] Please refer to Figure 10 In some embodiments, the top width of the electrode finger strip 22 is less than the bottom width, and the electrode finger strip 22 forms a first acute angle A and a second acute angle B with the piezoelectric substrate 10 on the two sides in the first direction X, and the angle difference between the first acute angle A and the second acute angle B is less than 5 degrees.

[0073] Specifically, for the electrode finger strip 22, whether it is the first electrode finger 221 or the second electrode finger 222, due to process technology problems, when the electrode finger strip 22 is processed on the piezoelectric substrate 10, the actual cross section of the electrode finger strip 22 is usually not a standard rectangle, but a trapezoid close to parallel from top to bottom. Among them, the top width of the electrode finger strip 22 is less than the bottom width, so that the top end surface of the electrode finger strip 22 forms two opposite inclined sides with the piezoelectric substrate 10, and the angle difference between the first acute angle A and the second acute angle B is limited to be less than 5 degrees through the process, so as to improve the sound wave excitation uniformity, frequency stability and process reliability.

[0074] In some embodiments, the angles of the first acute angle A and the second acute angle B are greater than or equal to 50 degrees and less than 90 degrees. For example, the first acute angle A is 85 degrees, the second acute angle B is 87 degrees, the angle difference between the first acute angle A and the second acute angle B is 2 degrees, and the top width of the electrode finger strip 22 is close to the bottom width, so that the cross section of the electrode finger strip 22 is close to the ideal rectangular shape. In other examples, the angles of the first acute angle A and the second acute angle B are set to 70 degrees, 75 degrees, 80 degrees, 81 degrees, 82 degrees, 83 degrees, 84 degrees, 85 degrees, 86 degrees, 87 degrees, 88 degrees, 89 degrees, etc.

[0075] Please refer to Figure 12In some embodiments, the interdigital transducer 20 further comprises a dummy finger structure 225 connected to the bus bar 21 and spaced opposite to the second electrode finger 222 on another bus bar 21.

[0076] Specifically, the dummy finger structure 225 is a virtual electrode in the non-active area (e.g. the edge or non-acoustic wave excitation area) of the electrode finger strip 22, which has a similar shape to the real electrode but does not participate in the electro-acoustic conversion process. By providing the dummy finger structure 225, the embodiments can further optimize the electric field distribution and suppress the mode effect, improve the frequency stability of the resonator and the main mode quality.

[0077] Referring to Figure 12 In some embodiments, in the second direction Y, the projection of the dummy finger structure 225 at least partially overlaps the second electrode finger 222, and the dummy finger structure 225 is spaced apart from the second electrode finger 222 to break the phase matching condition of the transverse acoustic wave. For example, by adjusting the distance or period between the dummy finger structure 225 and the second electrode finger 222, the transverse acoustic wave can be attenuated due to phase mismatch during propagation, thereby suppressing the coupling of the mode energy and suppressing the mode.

[0078] Referring to Figure 13 In some embodiments, in the first direction X, the adjacent first electrode finger 221 and the second electrode finger 222 form a group, and the first electrode finger 221 and the second electrode finger 222 in the same group have a geometric center O, and each geometric center O forms a division line 223, and the division line 223 is not parallel to the bus bar 21.

[0079] Specifically, unlike the embodiment of setting the division point at the connection between the first electrode finger 221 and the second electrode finger 222, the present embodiment uses another division method, in which the adjacent two electrode finger strips 22 in the first direction X form a group, and in the two electrode finger strips 22, the center position (e.g. the center of the dashed box) formed by the aperture of the adjacent first electrode finger 221 and the aperture of the second electrode finger 222 is the geometric center O, and the division line 223 is formed by sequentially connecting each geometric center O. By using the above division method, when the electrode finger strip 22 is processed, the projection of the adjacent two first electrode fingers 221 or second electrode fingers 222 in the first direction X on the same side of the division line 223 can be avoided, and the frequency deviation Δf can be avoided to be too large to affect the main mode resonance frequency Fr, so that the main mode quality is not affected, and the transverse mode is maximally suppressed. Figure 13

[0080] Of course, in other embodiments, other methods of forming the division line 223 can also be used, which are not limited here.

[0081] Referring to Figure 3 ​In some embodiments, the resonator 100 further comprises two reflective gratings 30, the interdigital transducer 20 is arranged between the two reflective gratings 30 along the first direction X, that is, the two reflective gratings 30 are arranged on both sides of the interdigital transducer 20 along the propagation direction of the acoustic wave, and the reflective gratings 30 are used to confine the surface acoustic wave in the interdigital transducer 20, thereby improving the main mode quality.

[0082] In the embodiment, in the electrode fingers 22 close to the reflective gratings 30, the length of the second electrode finger 222 is greater than the length of the first electrode finger 221. In the electrode fingers 22 with the same distance from the two reflective gratings 30 (i.e., the position of the wave peak of the curve), the length of the first electrode finger 221 is greater than the length of the second electrode finger 222, thereby forming a curved dividing line 223. On the same side of the dividing line 223, the resonant frequency deviation between the first electrode finger 221 and the second electrode finger 222 is ensured to be less than 0.01*Fr, so that the main mode resonant frequency of the resonator 100 is close to Fr, thereby avoiding affecting the main mode quality. On the basis of suppressing the transverse mode, the main mode quality is ensured not to be affected, thereby maximally suppressing the transverse mode.

[0083] The embodiment of the present application also provides a filter, which comprises the resonator 100 in any of the above embodiments.

[0084] Specifically, since the resonator 100 alternately arranges the first electrode fingers 221 on the two bus bars 21, and each first electrode finger 221 on each bus bar 21 is correspondingly connected to one second electrode finger 222, a sound velocity gradient is formed between the second electrode finger 222 and the first electrode finger 221, the propagation of the transverse mode is disturbed, it is difficult to form stable resonance in the transverse region of the resonator 100, the transverse mode resonance condition cannot be met, and thus the transverse mode is suppressed.

[0085] In some embodiments, the number of resonators 100 can be multiple, and the multiple resonators 100 can be arranged according to requirements. The multiple can be two, three or more.

[0086] In some embodiments, the filter can be a ladder structure filter, and the ladder structure filter can comprise multiple series arm resonators 100 and multiple parallel arm resonators 100, at least one of the multiple series arm resonators 100 and the multiple parallel arm resonators 100 is the resonator 100 in the above embodiment. In other embodiments, the filter can also be other types of filters.

[0087] In a specific example, the filter at least comprises a parallel arm resonator 100, and only the parallel arm resonator 100 adopts the resonator 100 in the above embodiment.

[0088] In addition, since the filter comprises the resonator 100, the filter has all the beneficial effects of the resonator 100, which will not be repeated here.

[0089] The embodiment of the present application also provides a radio frequency front-end module, which comprises the filter in the above embodiment.

[0090] Specifically, the resonator 100 in the filter is arranged alternately with the first electrode fingers 221 on the two bus bars 21, and the first electrode fingers 221 on each bus bar 21 are connected with a second electrode finger 222, so that the sound velocity gradient is formed between the second electrode finger 222 and the first electrode finger 221, the propagation of the transverse mode is interfered, it is difficult to form stable resonance in the transverse area of the resonator 100, the transverse mode resonance condition cannot be met, and the generation of the transverse mode is inhibited.

[0091] In some embodiments, the radio frequency front-end module can be applied to an electronic device, which can include but is not limited to a tablet computer, a notebook computer, a desktop computer, a navigator, a mobile phone, an electronic watch and other electronic devices or components with a wireless communication function, and the present embodiment is not limited thereto. The radio frequency front-end module can include a plurality of filters, and the plurality of filters can be two, three or more.

[0092] In some embodiments, the radio frequency front-end module can further include a low-noise amplifier, a radio frequency switch and a power amplifier, and the specific connection mode can refer to the prior art, which will not be described here. In addition, since the radio frequency front-end module includes the filter, and the filter includes the resonator 100, the radio frequency front-end module has all the beneficial effects of the filter and the resonator 100, which will not be described here.

[0093] It should be understood that the term "and / or" used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. It should be noted that in this document, the term "comprise", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or system including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or system. Without more limitation, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or system including the element.

[0094] The above-mentioned serial numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments. The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A resonator, characterized in that, The device includes a piezoelectric substrate and an interdigital transducer, wherein the interdigital transducer is disposed on the piezoelectric substrate, and the interdigital transducer includes: Two busbars arranged opposite each other along the second direction; and The electrode bar includes multiple first electrode fingers and multiple second electrode fingers. The multiple first electrode fingers are respectively connected to two busbars, and the first electrode fingers are arranged at intervals in a first direction. Each second electrode finger is connected to each of the first electrode fingers in a one-to-one correspondence. One end of the first electrode finger is connected to the busbar, and the other end of the first electrode finger is connected to the second electrode finger. The second electrode fingers are arranged at intervals with respect to the busbars. The second electrode fingers connected to each first electrode finger are arranged at intervals in the first direction. The first direction intersects the second direction, and the first direction is the direction of sound wave propagation. Wherein, the first electrode finger has a first finger width, the second electrode finger has a second finger width, and the first finger width is different from the second finger width; The resonant frequency corresponding to the first electrode finger is the first frequency F1, and the resonant frequency corresponding to the second electrode finger is the second frequency F2. There is a dividing line between the first electrode finger and the second electrode finger. On the same side of the dividing line, along the first direction, the difference between the first frequency F1 and the second frequency F2 is less than 0.01*Fr, where Fr is the main mode resonant frequency of the resonator.

2. The resonator according to claim 1, characterized in that, The width of the first finger is greater than the width of the second finger, or the width of the first finger is less than the width of the second finger.

3. The resonator according to claim 1, characterized in that, Each of the first electrodes is arranged at equal intervals in a first direction.

4. The resonator according to claim 1, characterized in that, Each of the second electrodes is arranged at equal intervals in the first direction.

5. The resonator according to claim 2 or 4, characterized in that, The sum of the width of the gap on both sides of the first electrode finger and the width of the first finger is the first width, and the sum of the width of the gap on both sides of the second electrode finger and the width of the second finger is the second width, and the first width and the second width are the same.

6. The resonator according to claim 5, characterized in that, In the first direction, the center line of the first electrode finger is aligned with the center line of the second electrode finger.

7. The resonator according to claim 5, characterized in that, In the first direction, one side of the first electrode finger is aligned with one side of the second electrode finger.

8. The resonator according to claim 1, characterized in that, A dividing point is provided at the connection between each of the first electrode fingers and each of the second electrode fingers, and the dividing points are connected in sequence to form the dividing line, which is not parallel to the bus bar.

9. The resonator according to claim 8, characterized in that, The dividing line includes any one of a curve, a broken line, or a toothed line.

10. The resonator according to claim 9, characterized in that, The dividing line is a curve, and at the peak of the curve, along the second direction, the length of the first electrode finger is greater than the length of the second electrode finger.

11. The resonator according to claim 1, characterized in that, Along the second direction, the length of the first electrode finger is different from the length of the second electrode finger.

12. The resonator according to claim 9, characterized in that, The aperture of the first electrode finger is the same as that of the second electrode finger.

13. The resonator according to claim 1, characterized in that, The first frequency F1 pointed to by the first electrode is the same as the second frequency F2 pointed to by the second electrode.

14. The resonator according to claim 1, characterized in that, The second electrode finger has a fingertip structure at the end away from the first electrode finger, and the size of the fingertip structure in the first direction is greater than or equal to the size of the second electrode finger; and / or The size of the fingertip structure in the third direction is greater than or equal to the size of the second electrode finger; the third direction is perpendicular to the first direction and the second direction.

15. The resonator according to claim 1, characterized in that, The top width of the electrode finger strip is smaller than its bottom width. The electrode finger strip forms a first acute angle and a second acute angle with the piezoelectric substrate on two sides in the first direction, respectively. The angle difference between the first acute angle and the second acute angle is less than 5 degrees.

16. The resonator according to claim 15, characterized in that, The angle between the first acute angle and the second acute angle is greater than or equal to 50 degrees and less than 90 degrees.

17. The resonator according to claim 1, characterized in that, The interdigital transducer also includes a pseudofinger structure connected to the busbar and spaced opposite to the second electrode finger on another busbar.

18. A resonator, characterized in that, The device includes a piezoelectric substrate and an interdigital transducer, wherein the interdigital transducer is disposed on the piezoelectric substrate, and the interdigital transducer includes: Two busbars arranged opposite each other along the second direction; and The electrode bar includes multiple first electrode fingers and multiple second electrode fingers. The multiple first electrode fingers are respectively connected to two busbars, and the first electrode fingers are arranged at intervals in a first direction. Each second electrode finger is connected to each of the first electrode fingers in a one-to-one correspondence. One end of the first electrode finger is connected to the busbar, and the other end of the first electrode finger is connected to the second electrode finger. The second electrode fingers are arranged at intervals with respect to the busbars. The second electrode fingers connected to each first electrode finger are arranged at intervals in the first direction. The first direction intersects the second direction, and the first direction is the direction of sound wave propagation. Wherein, the first electrode finger has a first finger width, the second electrode finger has a second finger width, and the first finger width and the second finger width are different; in the first direction, adjacent first electrode fingers and second electrode fingers form a group, and the first electrode fingers and second electrode fingers in the same group have a geometric center, each geometric center forms a dividing line, and the dividing line is not parallel to the bus bar.

19. The resonator according to claim 18, characterized in that, The resonant frequency corresponding to the first electrode finger is the first frequency F1, and the resonant frequency corresponding to the second electrode finger is the second frequency F2. The first electrode finger and the second electrode finger are connected by the dividing line. On the same side of the dividing line, along the first direction, the difference between the first frequency F1 and the second frequency F2 is less than 0.01*Fr, where Fr is the main mode resonant frequency of the resonator.

20. The resonator according to claim 18, characterized in that, Along the second direction, the length of the first electrode finger is different from the length of the second electrode finger.

21. The resonator according to claim 20, characterized in that, The dividing line is a curve, and at the peak of the curve, along the second direction, the length of the first electrode finger is greater than the length of the second electrode finger.

22. The resonator according to claim 18, characterized in that, The resonator further includes two reflective grids, and the interdigital transducer is disposed between the two reflective grids along the first direction; Among the electrode fingers near the reflective grating, the length of the second electrode finger is greater than the length of the first electrode finger.

23. A filter, characterized in that, Including the resonator as described in any one of claims 1 to 22.

24. A radio frequency front-end module, characterized in that, Includes the filter as described in claim 23.

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