Filter, radio frequency front-end module and electronic equipment

Abstract

The utility model relates to a filter, a radio frequency front-end module and electronic equipment, the filter comprises a piezoelectric substrate, two bus bars and a plurality of electrode fingers, the two bus bars and the plurality of electrode fingers are arranged on the piezoelectric substrate, the plurality of electrode fingers are located between the two bus bars, the electrode fingers are connected with one bus bar and spaced from the other bus bar, and the piezoelectric substrate is arranged on the piezoelectric substrate. The electrode fingers connected with different bus bars are arranged alternately; the side, facing the electrode fingers, of the bus bar is provided with a plurality of protruding parts, each protruding part is aligned with and spaced from the electrode fingers not connected with the bus bar, and in all the electrode fingers connected with the bus bar, the finger ends of at least part of the electrode fingers are fitted to form a first fitting line. The end part of the lug boss close to one side of the bus bar is fitted to form a second fitting line; wherein functions satisfied by the first fitting lines and the second fitting lines are periodic functions. According to the filter disclosed by the invention, the Q value of the filter is improved by adjusting the distance between at least part of the aligned electrode fingers and the lug bosses.

Description

Technical Field

[0001] This application relates to the field of radio frequency, and more particularly to a filter, a radio frequency front-end module including the filter, and an electronic device including the radio frequency front-end module. Background Technology

[0002] In the field of radio frequency (RF), filters typically consist of a piezoelectric substrate and multiple interdigital transducers. Through the interaction of the interdigital transducers with the piezoelectric substrate, the conversion between electrical signals and acoustic signals is achieved.

[0003] However, in related technologies, the electric field generated during the operation of the filter will concentrate around the busbar of the interdigital transducer, resulting in a low uniformity of the electric field of the filter, which affects the filter's performance and quality factor (Q value). Utility Model Content

[0004] In view of the shortcomings of the above-mentioned related technologies, the purpose of this application is to provide a solution to improve the Q value, specifically including the following technical solution:

[0005] In a first aspect, embodiments of this application provide a filter, including:

[0006] The piezoelectric substrate, and two busbars and a plurality of electrode fingers disposed on the piezoelectric substrate, the busbars being spaced apart along a first direction and extending along a second direction, the plurality of electrode fingers being located between the two busbars, the electrode fingers being connected to one busbar and spaced apart from the other busbar, the electrode fingers connected to different busbars being alternately arranged along the second direction, the second direction intersecting the first direction;

[0007] Along the first direction, the busbar has multiple protrusions on the side facing the electrode finger. Each protrusion is aligned with and spaced apart from the electrode finger not connected to the busbar. Among the electrode fingers connected to the busbar, at least some of the finger tips are fitted to form a first fitting line, and the ends of the protrusions near the side of the busbar are fitted to form a second fitting line.

[0008] Among them, the functions satisfied by each first fitting line and each second fitting line are periodic functions.

[0009] The filter of this application forms a first fitting line by fitting the fingertips of some electrode fingers and a second fitting line by fitting the ends of the protrusions, and makes both the first and second fitting lines curves. This results in multiple different spacings between the aligned electrode fingers and the protrusions, thereby adjusting the electric field distribution around the busbar, making the electric field relatively uniform, reducing the loss caused by electric field concentration, and thus improving the Q value of the filter of this application.

[0010] The filter in this application further improves the Q value of the filter by setting the functions satisfied by both the first and second fitting lines to periodic functions. This results in periodic anomalous changes in the fingertips of the electrodes used to fit the first fitting line and the ends of the protrusions used to fit the second fitting line, facilitating the adjustment of the electric field distribution and further enhancing the Q value of the filter. It also facilitates the fabrication of the filter.

[0011] In one embodiment, the number of periods of the functions satisfied by the first fitting line and the second fitting line is less than or equal to 50.

[0012] In one embodiment, at different locations in the second direction, the first fitted line and the second fitted line are spaced equally apart in the first direction.

[0013] In one embodiment, the first fitted line satisfies a first function, which includes any one of a sine function, a cosine function, and an envelope function; and / or, the second fitted line satisfies a second function, which includes any one of a sine function, a cosine function, and an envelope function, wherein a and b are both constants.

[0014] In one embodiment, the first fitting line and the second fitting line are set to the same function; wherein, a fitting midline is formed between two adjacent first fitting lines, the fitting midline is equidistant from the first fitting lines on both sides, and at the same position, the fitting midline is equidistant from the second fitting lines on both sides.

[0015] In one embodiment, along a first direction, the electrode fingers with the largest and smallest spacing between them and the spaced-apart busbars are both first electrode fingers; each first electrode finger includes two first sound velocity structures, one of which is located at the fingertip of the first electrode finger spaced apart from the busbar, and the other is close to the busbar connected to the first electrode finger; wherein, each first sound velocity structure close to the busbar side cooperates with the fingertip of other electrode fingers to form a first fitting line.

[0016] In one embodiment, the electrode finger further includes a plurality of second electrode fingers. Along a second direction, the ratio of the distance between the central axis of each second electrode finger and the central axis of the adjacent first electrode finger to one period of the first fitting line is less than or equal to 0.125. Each second electrode finger includes two second sound velocity structures, one of which is located at the fingertip of the second electrode finger, and the other is close to the busbar connected to the second electrode finger. The first sound velocity structures and the second sound velocity structures adjacent to each busbar cooperate with the fingertips of other electrode fingers to form the first fitting line.

[0017] In one embodiment, along the second direction, the width dimension of each first sound velocity structure is greater than the width dimension of the first electrode finger to which the first sound velocity structure is connected, and the material of the first sound velocity structure is the same as the material of the first electrode finger; and / or, along the second direction, the width dimension of each second sound velocity structure is greater than the width dimension of the second electrode finger to which the second sound velocity structure is connected, and the material of the second sound velocity structure is the same as the material of the second electrode finger.

[0018] In one embodiment, the distance between two first sound velocity structures along a first direction is the aperture size, and the distance between the central axes of two adjacent electrode fingers along a second direction is the finger spacing, wherein the ratio of the aperture size to the finger spacing is greater than or equal to 10.

[0019] In one embodiment, the aperture size includes a maximum aperture size and a minimum aperture size, wherein the ratio of the difference between the maximum aperture size and the minimum aperture size to the finger spacing is greater than or equal to 0.2 and less than or equal to 31.

[0020] In one embodiment, the region between two busbars includes a first region and a second region connected together. There are two first regions, and along a second direction, the second region is located between the two first regions. Multiple electrode fingers are distributed in each of the first and second regions. Among the electrode fingers connected to the busbars, the fingertips of the electrode fingers located in the first region are fitted to form a first fitting line, and within the first region, the fingertips of the protrusions facing the electrode finger side are fitted to form a second fitting line. Along the first direction, the lengths of the electrode fingers in the second region are equal and aligned with each other, and the lengths of the protrusions in the second region are equal.

[0021] In one embodiment, each electrode finger located in the second region includes two third sound velocity structures, one of which is located at the tip of the electrode finger and the other is located near the side of the busbar connected to the electrode finger.

[0022] In one embodiment, the electrode fingers in the first region that are close to the second region are flush with the electrode fingers in the second region that are close to the first region.

[0023] In one embodiment, the electrode finger in the first region that is close to the second region is the first electrode finger.

[0024] In one embodiment, each busbar further includes a busbar body, a connector, and a conductive element. The busbar body extends along a second direction. Along a first direction, the connector and the conductive element are located between the busbar body and a plurality of electrode fingers. Each connector is connected to a conductive element and the busbar body. The extension direction of the conductive element is parallel to the second direction. A protrusion is provided on the surface of the conductive element facing the electrode finger. One end of each electrode finger is connected to a busbar through a conductive element, and the other end is spaced apart from the protrusion of another conductive element.

[0025] In one embodiment, the connector, conductive element, and connected electrode fingers are integrated into one unit.

[0026] In one embodiment, each of the multiple electrode fingers includes multiple electrode finger groups, with each electrode finger located in at most one electrode finger group. The multiple electrode finger groups are arranged at intervals along a second direction. Each electrode finger group includes two adjacent electrode fingers, as well as a connector and a conductive element arranged on both sides of the two electrode fingers along a first direction. The projections of the two electrode fingers onto the conductive element along the first direction are located on the conductive element. Any one of the two electrode fingers is connected to one conductive element and spaced apart from the protrusion of the other conductive element.

[0027] Secondly, embodiments of this application provide a radio frequency front-end module, including a filter.

[0028] Thirdly, embodiments of this application provide an electronic device, including a radio frequency front-end module.

[0029] Understandably, the RF front-end module provided in the second aspect and the electronic device provided in the third aspect of this application, because they employ the filter provided in the first aspect of this application, also have better Q values. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application;

[0031] Figure 2 This is a schematic diagram of the structure of the radio frequency front-end module provided in one embodiment of this application;

[0032] Figure 3 This is a schematic diagram of the filter structure provided in one embodiment of this application;

[0033] Figure 4 This is a schematic diagram of another structure of the filter provided in one embodiment of this application;

[0034] Figure 5 This is a partial structural diagram of the filter provided in one embodiment of this application;

[0035] Figure 6 This is another schematic diagram of the structure of the filter provided in one embodiment of this application;

[0036] Figure 7 This is a schematic diagram of another partial structure of the filter provided in one embodiment of this application;

[0037] Figure 8 This is another schematic diagram of the structure of the filter provided in one embodiment of this application;

[0038] Figure 9 This is a cross-sectional structural diagram of a filter provided in one embodiment of this application;

[0039] Figure 10 This is a schematic cross-sectional view of another filter provided in one embodiment of this application;

[0040] Figure 11 This is a top view of the filter structure provided in one embodiment of this application;

[0041] Figure 12 This is a schematic diagram of the surface structure of the filter provided in one embodiment of this application;

[0042] Figure 13 This is a top view schematic diagram of another filter structure provided in one embodiment of this application;

[0043] Figure 14 This is another top view of the filter provided in one embodiment of this application;

[0044] Figure 15 This is another top view of the filter provided in one embodiment of this application. Detailed Implementation

[0045] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0046] The following descriptions of the embodiments are based on the accompanying illustrations and are used to illustrate specific embodiments in which this application can be implemented. The component designations used herein, such as "first," "second," etc., are merely for distinguishing the described objects and have no sequential or technical meaning. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages). Directional terms used in this application, such as "up," "down," "front," "rear," "left," "right," "inner," "outer," "side," etc., are merely for reference to the accompanying illustrations. Therefore, the use of directional terms is for better and clearer explanation and understanding of this application, and does not indicate or imply that the referred device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this application.

[0047] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising," "may include," "include," or "may include" used in this application indicate the presence of the corresponding disclosed function, operation, element, etc., and do not limit one or more other functions, operations, elements, etc. Moreover, the terms "comprising" or "include" indicate the presence of the corresponding features, numbers, steps, operations, elements, components, or combinations thereof disclosed in the specification, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, and are intended to cover non-exclusive inclusion.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0049] Please see Figure 1 The diagram shown is a structural schematic of an electronic device 300 provided in one embodiment of this application.

[0050] like Figure 1 As shown, the electronic device 300 of this application includes a substrate 301 and a radio frequency front-end module 200, with the radio frequency front-end module 200 mounted on the substrate 301. The substrate 301 and the radio frequency front-end module 200 are electrically connected.

[0051] In one embodiment, the substrate 301 is a printed circuit board to control the operation of the radio frequency front-end module 200. The electronic device 300 of this application receives and / or transmits signals through the radio frequency front-end module 200. Exemplarily, the electronic device 300 includes at least one of a computer, mobile phone, tablet computer, smartwatch, and navigator, etc., and this application does not impose any particular limitation on this.

[0052] Please see Figure 2 The diagram shown is a structural schematic of the radio frequency front-end module 200 provided in one embodiment of this application.

[0053] like Figure 2As shown, the RF front-end module 200 includes a signal terminal 201, a switch 202, an amplifier 203, and a filter 100. The signal terminal 201 is used to receive external signals or transmit RF signals. The switch 202 is located between the signal terminal 201 and the filter 100 to control signal transmission between them. When the amplifier 203 is a low-noise amplifier, when the switch 202 is closed, the filter 100 receives the external signal received by the signal terminal 201 and outputs a signal with a preset frequency.

[0054] Amplifier 203 is electrically connected to filter 100 to amplify the signal processed by filter 100 and output it to subsequent structures. When amplifier 203 is a power amplifier, filter 100 is used to receive the amplified radio frequency signal after the amplification of amplifier 203 when switch 202 is closed, filter the received radio frequency signal, and then transmit the filtered radio frequency signal to signal terminal 201 through switch 202. In one embodiment, signal terminal 201 is an antenna.

[0055] In one embodiment, the number of filters 100 may be multiple, and all multiple filters 100 are communicatively connected to the signal terminal 201.

[0056] In one embodiment, the radio frequency front-end module 200 further includes a multiplexer, which includes a filter 100.

[0057] Please see Figure 3 The diagram shown is a structural schematic of the filter 100 provided in one embodiment of this application.

[0058] like Figure 3 As shown, the filter 100 of this application includes a piezoelectric substrate 10, busbars 21, and electrode fingers 22. There are two busbars 21 and multiple electrode fingers 22. The two busbars 21 are arranged parallel to each other and spaced apart along a first direction 001, and extend along a second direction 002. Each electrode finger 22 is located between the two busbars 21, and is arranged parallel to each other and spaced apart along the second direction 002.

[0059] In this configuration, one of the two busbars 21 is used to receive external signals, while the other busbar 21 is used to output signals. Multiple electrode fingers 22 are located between the two busbars 21. Some of the electrode fingers 22 are connected to one busbar 21, while other electrode fingers 22 are connected to the other busbar 21.

[0060] For ease of description, the busbar 21 used for receiving external signals is defined as the first busbar 21a, and the busbar 21 used for outputting signals is defined as the second busbar 21b. The electrode finger 22 connected to the first busbar 21a is defined as the first electrode 22a, and the electrode finger 22 connected to the second busbar 21b is defined as the second electrode 22b.

[0061] Specifically, the first electrode 22a and the second electrode 22b are arranged alternately along the first direction 001. Both the first electrode 22a and the second electrode 22b extend along the second direction 002 towards opposite sides of the piezoelectric substrate 10. Specifically, as... Figure 3 As shown, along the second direction 002, there is a first electrode 22a between any two adjacent second electrodes 22b, and there is a second electrode 22b between any two adjacent first electrodes 22a.

[0062] Both the first busbar 21a and the second busbar 21b extend along the second direction 002 toward opposite sides of the piezoelectric substrate 10. In actual application, the filter 100 of this application may have errors. The angle between the first direction 001 and the second direction 002 may not be equal to 90°. If the angle between the first direction 001 and the second direction 002 is less than 90°, the above situations are all within the protection scope of this application.

[0063] In this embodiment, due to the inverse piezoelectric effect of the piezoelectric substrate 10, when an electrical signal is transmitted to each of the second electrodes 22b via the first busbar 21a, the electrical signal on each of the second electrodes 22b releases an electrostatic force on the piezoelectric substrate 10, causing deformation of the surface of the piezoelectric substrate 10. Since the electrical signal is an alternating signal, it is understandable that the electrostatic force exerted by each of the second electrodes 22b on the surface of the piezoelectric substrate 10 exhibits a periodic variation. Correspondingly, the amount of deformation of the surface of the piezoelectric substrate 10 also varies with the periodic variation of the electrical signal, thereby forming an outwardly released surface acoustic wave.

[0064] Surface acoustic waves (SAWs) are used to achieve the frequency selection and signal processing functions of the filter 100 of this application. During SAW propagation, the primary propagation direction is the second direction 002. However, in practice, due to edge effects and acoustic diffraction, the propagation direction of the SAW formed on the surface of the piezoelectric substrate 10 may also be other directions. In one embodiment, SAWs propagating in other directions are absorbed by a sound-absorbing material (not shown in the figure).

[0065] It is understood that any two adjacent busbars 21 and the electrode fingers 22 between the two busbars 21 in the filter 100 of this application are used to form a surface acoustic wave (SAW) resonator in conjunction with the piezoelectric substrate 10. The SAW resonator can be a normal SAW resonator, a temperature-compensated SAW resonator (TC-SAW), a SAW resonator with a multilayer substrate structure, or a laterally excited thin-film bulk acoustic wave resonator, etc.

[0066] In the embodiments of this application, such as Figure 3 As shown, along the first direction 001, the busbar 21 has multiple protrusions 211 on the side facing the electrode finger 22. Each protrusion 211 is aligned with and spaced apart from an electrode finger 22 not connected to that busbar 21. Specifically, along the first direction 001, the surface of the first busbar 21a facing the second electrode 22b has multiple protrusions 211, which are spaced apart from the second electrode 22b and aligned with each other along the first direction 001. The surface of the second busbar 21b facing the first electrode 22a has multiple protrusions 211, which are spaced apart from the second electrode 22b and aligned with each other along the first direction 001.

[0067] At least a portion of the fingertips of the electrode fingers 22 are fitted to form a first fitting line L1, and the end of the protrusion 211 near the busbar 21 is fitted to form a second fitting line L2. It is worth mentioning that the protrusion 211 required for fitting the second fitting line L2 is the same protrusion 211 required for aligning the electrode fingers 22 for fitting the first fitting line L1.

[0068] In one embodiment, in Figure 3 In the schematic diagram shown, there are two first fitting lines L1 and two second fitting lines L2. Specifically, the fingertips of all second electrodes 22b are fitted to form one first fitting line L1, the fingertips of all first electrodes 22a are fitted to form another first fitting line L1, the ends of all protrusions 211 aligned with the second electrodes 22b are fitted to form one second fitting line L2, and the ends of all protrusions 211 aligned with the first electrodes 22a are fitted to form another second fitting line L2. In this embodiment, when fitting different fitting lines, the midpoints of the ends of each part can be found first, and then different midpoints are fitted to obtain the first fitting line L1 and the second fitting line L2 in this embodiment. For example, when forming the first fitting line L1, the midpoints corresponding to the side edges of the ends of different second electrodes 22b are determined sequentially, and then the fitting is performed based on multiple midpoints.

[0069] In this embodiment, both the first fitting line L1 and the second fitting line L2 are curves, such that in each electrode finger 22 and protrusion 211 formed as the first fitting line L1 and the second fitting line L2, there are multiple different spacings between each electrode finger 22 and the busbar 21, and each protrusion 211 has a different length dimension.

[0070] Specifically, for any given electrode finger 22 and protrusion 211, if the distance between the electrode finger 22 and the busbar 21 is too large, or if the length of the protrusion 211 is too long, the electric field concentration formed by the interaction of the electrode fingers 22 is poor, resulting in low electric field coupling efficiency and reduced Q value and performance of the filter 100. Conversely, if the distance between the electrode finger 22 and the busbar 21 is too small, or if the length of the protrusion 211 is too short, the electric field formed by the interaction of the electrode fingers 22 is overly concentrated at the fingertips, potentially leading to increased losses in the electrode fingers 22 and consequently a decrease in the Q value of the filter 100.

[0071] Therefore, in this embodiment, the first fitting line L1 and the second fitting line L2 in the filter 100 are set as curves, resulting in multiple different spacings between each electrode finger 22 and the busbar 21, and multiple different lengths for each protrusion 211. This adjusts the distribution of the electric field and prevents the electric field from becoming too concentrated at the tips of the electrode fingers 22, thus avoiding losses. This improves the operating performance and Q value of the filter 100.

[0072] It is worth noting that in the embodiments of this application and subsequent embodiments, the first fitting line L1 and the second fitting line L2 are set as curves, that is, apodization processing is performed on the electrode finger 22 and the protrusion 211 respectively. In related technologies, apodization generally refers to a design method that optimizes the electrical performance of a resonator by changing the geometry, spacing, or arrangement of the electrode finger or bus bar. In the embodiments of this application and subsequent embodiments, apodization refers to the method of adjusting the geometry or spacing of the electrode finger or bus bar (including the protrusion) so that the spacing between the electrode finger and the bus bar changes.

[0073] In one embodiment, the functions satisfied by each first fitting line L1 and each second fitting line L2 are periodic functions. That is, the fingertips of each electrode finger 22 used to fit the first fitting line L1 exhibit periodic aberrations, and the ends of each protrusion 211 used to fit the second fitting line L2 also exhibit periodic aberrations.

[0074] Understandably, the periodic apodization of the electrode fingers 22 and the protrusions 211 helps to adjust the distribution of the electric field, making the electric field distribution more uniform. This further improves the Q value of the filter 100 of this application. On the other hand, the periodic arrangement also makes the lengths of each electrode finger 22 and the protrusions 211 change periodically, which also facilitates the fabrication of the filter 100 of this application.

[0075] In one embodiment, the two first fitting lines L1 have the same period. Since the arrangement of the first fitting lines L1 enables adjustment of the electric field distribution, along the first direction 001, the two first fitting lines L1 are located on opposite sides of each electrode finger 22. It is understood that setting the periods of the two first fitting lines L1 to be the same ensures that the adjustment effect of the first fitting lines L1 on the electric field distribution around the two busbars 21 is consistent, which helps to ensure the uniformity of the electric field and further improves the Q value of the filter 100 of this application.

[0076] In one embodiment, the two second fitting lines L2 have the same period. Since the arrangement of the second fitting lines L2 enables adjustment of the electric field distribution, along the first direction 001, the two second fitting lines L2 are located on opposite sides of each electrode finger 22. It is understood that setting the periods of the two second fitting lines L2 to be the same ensures that the adjustment effect of the second fitting lines L2 on the electric field distribution around the two busbars 21 is consistent, which helps to ensure the uniformity of the electric field and further improves the Q value of the filter 100 of this application.

[0077] In one embodiment, the two first fitting lines L1 have the same period, and the two second fitting lines L2 have the same period. Based on the above description, setting the periods of the two first fitting lines L1 and the two second fitting lines L2 to be the same ensures that the electric field distribution around the two busbars 21 is relatively consistent, thereby further guaranteeing the uniformity of the electric field distribution and further improving the Q value of the filter 100 of this application.

[0078] In one embodiment, such as Figure 3 As shown, the first fitting line L1 and the second fitting line L2 are set to the same function. A fitting midline L3 is formed between two adjacent first fitting lines L1, and the fitting midline L3 is equidistant from both first fitting lines L1. Similarly, at the same location, the fitting midline L3 is equidistant from both second fitting lines L2. Optionally, the distance difference between the fitting midline and the two first fitting lines L1 is less than or equal to λ, where λ is the sound wave period. This avoids the impact of manufacturing process deviations on performance.

[0079] That is, at any position on the second direction 002, the spacing between two adjacent first fitting lines L1 along the first direction 001 is equal, and the spacing between two adjacent second fitting lines L2 along the first direction 001 is equal, so that the electric field of the filter 100 at the first busbar 21a and the second busbar 21b can be symmetrically distributed, thereby further improving the uniformity of the electric field distribution when the filter 100 is working, and further improving the Q value of the filter 100.

[0080] In one embodiment, the number of periods of the functions satisfied by the first fitted line L1 and the second fitted line L2 is less than or equal to 50. For example, the number of periods of the function is any one of 10, 15, 20, 25, 30, 35, and 45.

[0081] For the first fitted line L1, the number of electrode fingers 22 is limited. The filter 100 of this application sets the number of periods of the function satisfied by the first fitted line L1 to be less than or equal to 50. This avoids a situation where the number of electrode fingers 22 required in one period is too small due to an excessively large number of periods, resulting in a mismatch between the fitted function of the first fitted line L1 and the function corresponding to the first fitted line L1. This facilitates the fabrication of the filter 100 of this application.

[0082] For the second fitting line L2, the number of protrusions 211 is limited. The filter 100 of this application sets the number of periods of the function satisfied by the second fitting line L2 to be less than or equal to 50. This avoids a situation where the number of electrode fingers 22 arranged in one period is too small due to an excessively large number of periods, resulting in a mismatch between the fitting function of the second fitting line L2 and the function corresponding to the second fitting line L2. This facilitates the fabrication of the filter 100 of this application.

[0083] In one embodiment, at different positions on the second direction 002, the distance between the first fitting line L1 and the second fitting line L2 on the first direction 001 is equal. That is, along the first direction 001, the distance between any two mutually aligned protrusions 211 and electrode fingers 22 is equal. This simplifies the manufacturing requirements of the filter 100 of this application and facilitates its fabrication.

[0084] On the other hand, to avoid the impact on the uniformity of electric field distribution caused by the inconsistent spacing between the electrode finger 22 and the protrusion 211, the uniformity of electric field distribution during the operation of the filter 100 of this application is further guaranteed, the energy loss caused by uneven distribution is reduced, and the Q value of the filter 100 of this application is improved.

[0085] In one embodiment, the first fitting line L1 satisfies a first function, which includes a sine function or a cosine function. On the one hand, this makes the apodization of each electrode finger 22 relatively smooth, avoiding the phenomenon of increased energy loss due to excessive length differences between adjacent electrode fingers 22. This improves the Q value of the filter 100 of this application. On the other hand, setting the first function to any one of a sine function, a cosine function, or an envelope function also facilitates the design and fabrication of the filter 100 of this application.

[0086] In one embodiment, the first fitted line L1 satisfies a first function, the expression of which is Y. A (x)=Y A1 (x)×Y A2 (x).

[0087] Among them, Y A1 The function expression for (x) is A, 1 / (x) n +b), x n +b, A cos(ax+θ), and A sin(ax+θ), where A, a, b, and n are all constants. In one embodiment, A may be set to an integer less than 10; for example, A is 4 or 6.

[0088] Y A2 The functional expressions for (x) are A cos(ax+θ), A sin(ax+θ) and In this context, A, a, and n are all constants, and T is the period of the function. In one embodiment, A can be set to an integer less than 10; for example, A is 6 or 8. Optionally, Y... A (x) = 6cos(x).

[0089] In one embodiment, the second fitted line L2 satisfies a second function, which includes any one of a sine function, a cosine function, or an envelope function. Similarly, as described above, setting the second function to a sine or cosine function improves the Q value of the filter 100 of this application and also facilitates the design and fabrication of the filter 100.

[0090] In the embodiments of this application, the envelope function may include (ax+b)*cosx, (e... x Any of the following: )*sinx

[0091] In one embodiment, the second fitted line L2 satisfies a second function, the expression of which is Y. B (x)=Y B1 (x)×Y B2 (x).

[0092] Among them, YB1 The function expression for (x) is A, 1 / (x) n +b), x n +b, A cos(ax+θ), and A sin(ax+θ), where A, a, b, and n are all constants. In one embodiment, A may be set to an integer less than 10; for example, A is 4 or 6.

[0093] Y B2 The functional expressions for (x) are A cos(ax+θ), A sin(ax+θ) and In this context, A, a, and n are all constants, and T is the period of the function. In one embodiment, A can be set to an integer less than 10; for example, A is 6 or 8.

[0094] Please refer to the above. Figure 4 and Figure 5 ,in Figure 4 This is another structural schematic diagram of the filter 100 provided in one embodiment of this application. Figure 5 This is a partial structural diagram of the filter 100 provided in one embodiment of this application.

[0095] like Figure 4 and Figure 5 As shown, along the first direction 001, some electrode fingers 22 are spaced apart from the busbars 21. Because the distance between the electrode fingers 22 and their corresponding busbars 21 varies, different spacing values ​​are provided between the electrode fingers 22 and the busbars 21. Specifically, there are a first spacing and a second spacing between the electrode fingers 22 and the busbars 21; wherein the electrode fingers corresponding to the first spacing and the second spacing are both first electrode fingers 22. In this embodiment, the electrode fingers with the largest and smallest spacing between them and the spaced-apart busbars are both first electrode fingers. Specifically, the first spacing is the largest spacing between the electrode fingers 22 and the spaced-apart busbars 21, and the second spacing is the smallest spacing between the electrode fingers 22 and the spaced-apart busbars 21. That is, when the function satisfied by the first fitted line L1 is a sine function or a cosine function, the first electrode finger 221 refers to the electrode finger 22 located at the peak or trough, where the peak or trough represents the minimum or maximum spacing value.

[0096] like Figure 5 As shown, each first electrode finger 221 includes two first sound velocity structures 31. One first sound velocity structure 31 is located at the fingertip of the first electrode finger 221 that is spaced apart from the busbar 21, and the other first sound velocity structure 31 is close to the busbar 21 connected to the first electrode finger 221. The first sound velocity structures 31 on the side close to the busbar 21 are fitted together with the fingertips of other electrode fingers 22 to form a first fitting line L1.

[0097] For example, in Figure 5 In the schematic diagram shown, within the region surrounding the first busbar 21a, a first electrode finger 221 serves as a second electrode 22b, spaced apart from the first busbar 21a. At this time, a first sound velocity structure 31 is provided at the tip of the first electrode finger 221. This first sound velocity structure 31 is used to cooperate with the tips of the fingers of each second electrode 22b to form a first fitting line L1. In this first fitting line L1, the first sound velocity structure 31 on the first electrode finger 221 is located at the peak or trough of the first fitting line L1.

[0098] In this embodiment, the provision of the first sound velocity structure 31 increases the mass load on the fingertip region of the first electrode finger 221, thereby adjusting the sound velocity in the fingertip region of the electrode finger 22, which in turn adjusts the sound field distribution during the operation of the filter 100, which is beneficial to improving the working performance and Q value of the filter 100.

[0099] On the other hand, since the first electrode finger 221 is the electrode finger 22 with the largest or smallest distance from the adjacent bus bar 21, for the first electrode finger 221 corresponding to the filter 100 of this application, when the distance between the first electrode finger 221 and the adjacent bus bar 21 is the maximum distance, the electric field distribution at the fingertip of the first electrode finger 221 is uniform, but the electric field strength is weak. When the distance between the first electrode finger 221 and the adjacent bus bar 21 is the minimum distance, the electric field distribution at the fingertip of the first electrode finger 221 is concentrated, and the electric field strength is strong.

[0100] Furthermore, the arrangement of the first sound velocity structure 31 enables the adjustment of the electric field distribution. It is understood that the filter 100 of this application adjusts the electric field distribution at the tip of the first electrode finger 221 by setting two first sound velocity structures 31 on the first electrode finger 221, thereby making the electric field generated by the filter 100 during operation relatively uniform, further improving the working performance and Q value of the filter 100.

[0101] Please refer to the above. Figure 6 and Figure 7 ,in Figure 6 This is another structural schematic diagram of the filter 100 provided in one embodiment of this application. Figure 7 This is a schematic diagram of another partial structure of the filter 100 provided in one embodiment of this application.

[0102] like Figure 6 and Figure 7As shown, electrode finger 22 also includes multiple second electrode fingers 222. Along the second direction 002, the ratio of the distance between the central axis of each second electrode finger 222 and the adjacent first electrode finger 221 to one period of the first fitting line L1 is less than or equal to 0.125. That is, when the function satisfied by the first fitting line L1 is a sine function or a cosine function, the distance between the second electrode finger 222 and the adjacent peaks or troughs of the first fitting line L1 is less than or equal to 0.125 times the period. Correspondingly, the second electrode finger 222 refers to the electrode fingers 22 within a range of 0.125 periods around the peaks or troughs of the first fitting line L1.

[0103] like Figure 7 As shown, each second electrode finger 222 includes two second sound velocity structures 32, one of which is located at the fingertip of the second electrode finger 222, and the other is close to the busbar 21 connected to the second electrode finger 222. The adjacent first sound velocity structures 31 and second sound velocity structures 32 of each busbar 21, in conjunction with the fingertips of other electrode fingers 22, form a first fitting line L1. In this first fitting line L1, the second sound velocity structures 32 on the second electrode finger 222 are located within a 0.125-period range around the peaks or troughs of the first fitting line L1.

[0104] In this embodiment, the provision of the second sound velocity structure 32 increases the mass load on the fingertip region of the second electrode finger 222, thereby adjusting the sound velocity in the fingertip region of the electrode finger 22. This adjusts the sound field distribution during the operation of the filter 100, which is beneficial to improving the working performance and Q value of the filter 100.

[0105] On the other hand, since the first electrode finger 221 is the electrode finger 22 with the largest or smallest distance from the adjacent bus bar 21, and the second electrode finger 222 is the electrode finger 22 with a distance from the first electrode finger 221 less than or equal to 0.125 times the period, for the second electrode finger 222 corresponding to the filter 100 of this application, when the first electrode finger 221 adjacent to the second electrode finger 222 is at the peak of the first fitting line L1, the electric field distribution at the fingertip of the second electrode finger 222 is relatively uniform, but the electric field strength is relatively weak. When the first electrode finger 221 adjacent to the second electrode finger 222 is at the trough of the first fitting line L1, the electric field distribution at the fingertip of the second electrode finger 222 is relatively concentrated, and the electric field strength is relatively strong.

[0106] Furthermore, the second sound velocity structure 32 enables the adjustment of the electric field distribution. It is understood that the filter 100 of this application, by setting two second sound velocity structures 32 on the second electrode finger 222, allows each second sound velocity structure 32 to cooperate with each first sound velocity structure 31 to adjust the electric field distribution at the fingertip of the electrode finger 22, thereby making the electric field generated by the filter 100 more uniform during operation, further improving the working performance and Q value of the filter 100.

[0107] In one embodiment, such as Figure 7 As shown, along the second direction 002, the width of the first sound velocity structure 31 is greater than the width of the first electrode finger 221 connected to it, and the material of the first sound velocity structure 31 is the same as that of the first electrode finger 221. That is, the filter 100 of this application forms two first sound velocity structures 31 by widening the fingertip of the first electrode finger 221 and a portion of the first electrode finger 221 near the connected busbar 21, thereby increasing the mass load of the fingertip region of the first electrode finger 221 and improving the working performance of the filter 100 of this application.

[0108] In one embodiment, such as Figure 7 As shown, along the second direction 002, the width of the second sound velocity structure 32 is greater than the width of the second electrode finger 222 connected to it, and the material of the second sound velocity structure 32 is the same as that of the second electrode finger 222. That is, the filter 100 of this application forms two second sound velocity structures 32 by widening the fingertip of the second electrode finger 222 and a portion of the second electrode finger 222 near the connected busbar 21, thereby increasing the mass load of the fingertip region of the second electrode finger 222 and improving the operating performance of the filter 100 of this application.

[0109] Please refer to the above. Figure 8 and Figure 9 ,in Figure 8 This is another structural schematic diagram of the filter 100 provided in one embodiment of this application. Figure 9 This is a schematic cross-sectional view of the filter 100 provided in one embodiment of this application. Figure 9 for Figure 8 A schematic diagram of the cross-sectional structure formed by cutting along section line P.

[0110] like Figure 8 and Figure 9As shown, along the surface perpendicular to the piezoelectric substrate 10, the height dimension of the first sound velocity structure 31 is greater than or equal to the height dimension of the first electrode finger 221 to which the first sound velocity structure 31 is connected. That is, by setting a higher structure on the first electrode finger 221 to form the first sound velocity structure 31, the filter 100 of this application increases the mass load of the fingertip region of the first electrode finger 221 and improves the working performance of the filter 100 of this application.

[0111] In one embodiment, along the surface perpendicular to the piezoelectric substrate 10, the height dimension of the second sound velocity structure 32 is greater than or equal to the height dimension of the second electrode finger 222 to which the second sound velocity structure 32 is connected. That is, by providing a higher structure on the second electrode finger 222 to form the second sound velocity structure 32, the filter 100 of this application increases the mass load of the fingertip region of the second electrode finger 222, thereby improving the operating performance of the filter 100 of this application.

[0112] Please refer to the above. Figure 10 The diagram shown is a cross-sectional view of another embodiment of the present application.

[0113] like Figure 10 As shown, along a surface perpendicular to the piezoelectric substrate 10, a first acoustic structure 31 is stacked on the surface of the first electrode finger 221 facing away from the piezoelectric substrate 10. That is, the filter 100 of this application increases the mass load on the fingertip region of the first electrode finger 221 by stacking the first acoustic structure 31 on the surface of the first electrode finger 221 facing away from the piezoelectric substrate 10, thereby improving the working performance of the filter 100 of this application.

[0114] In one embodiment, a second acoustic structure 32 is stacked on the surface of the second electrode finger 222 away from the piezoelectric substrate 10 along a surface perpendicular to the piezoelectric substrate 10. That is, the filter 100 of this application increases the mass load on the fingertip region of the first electrode finger 221 and improves the working performance of the filter 100 by stacking the second acoustic structure 32 on the surface of the second electrode finger 222 away from the piezoelectric substrate 10.

[0115] It is understood that in the above embodiments, the first sound velocity structure 31 and the second sound velocity structure 32 can be configured by increasing the width of the electrode finger 22, increasing the height of the electrode finger 22, or by depositing other materials on the surface of the electrode finger 22 away from the piezoelectric substrate 10. In another embodiment, the first sound velocity structure 31 and the second sound velocity structure 32 can simultaneously have a relatively wide width and a relatively high height. In other embodiments, the configuration and materials of the first sound velocity structure 31 and the second sound velocity structure 32 can be different. For example, the first sound velocity structure 31 is formed by widening the first electrode finger 221, while the second sound velocity structure 32 is formed by stacking other materials on the surface of the second electrode finger 222 away from the piezoelectric substrate 10.

[0116] In one embodiment, such as Figure 8 As shown, along the first direction 001, it also includes an aperture size L. Along the second direction 002, the distance between the central axes of two adjacent electrode fingers 22 is the finger spacing D. The ratio of the aperture size L to the finger spacing D is greater than or equal to 10. Wherein, the aperture size L is the size of the aperture region along the first direction 001, and the aperture region is defined as the overlapping area of ​​any two adjacent electrode fingers along the first direction 001.

[0117] In this embodiment, the first sound velocity structure 31 is disposed on the first electrode finger 221, and the first electrode finger 221 can be the electrode finger 22 with the smallest length dimension among all electrode fingers 22. Since the ratio of the aperture size L to the finger spacing D is greater than or equal to 10, the aperture corresponding to all electrode fingers is also greater than or equal to 10 times the finger spacing D.

[0118] Since the aperture region of filter 100 is the region where the main mode energy of filter 100 is concentrated, if the ratio between the aperture size L and the finger spacing D is too small, the equivalent area of ​​the main mode energy concentration region of filter 100 may be too small, thereby affecting the working performance of filter 100.

[0119] That is, the filter 100 of this application ensures that the ratio of the equivalent area of ​​the main mode energy concentration region to the area of ​​the main mode energy concentration region set in a conventional filter is within a preset range by setting an aperture size L that is greater than or equal to 10 times the finger pitch D, thereby guaranteeing the working performance of the filter 100 of this application. For example, the preset range is greater than or equal to 0.8 and less than or equal to 1.2.

[0120] In one embodiment, the aperture size L includes a maximum aperture size and a minimum aperture size. The ratio of the difference between the maximum and minimum aperture sizes to the finger spacing D is greater than or equal to 0.2 and less than or equal to 31. This ensures the effect of the first fitted line L1 on the electric field and guarantees the Q-value improvement of the filter 100 of this application.

[0121] Please refer to the above. Figure 11 The diagram shown is a top view of the filter 100 provided in one embodiment of this application.

[0122] like Figure 11As shown, the region between the two busbars 21 includes a connected first region A1 and a second region A2. There are two first regions A1. Along the second direction 002, the second region A2 is located between the two first regions A1. Multiple electrode fingers 22 are distributed within each of the first regions A1 and the second region A2. Among the electrode fingers 22 connected to the busbars 21, the fingertips of the electrode fingers 22 located in the first region A1 are fitted to form a first fitting line L1. Within the first region A1, the fingertips of the protrusions 211 facing the electrode fingers 22 are fitted to form a second fitting line L2. Along the first direction 001, the lengths of the electrode fingers 22 within the second region A2 are equal and aligned with each other.

[0123] That is, the electrode fingers 22 in the second region A2 between the two busbars 21 are not apodized, while the electrode fingers 22 in the first region A1 are apodized. Based on the effect of apodization on adjusting the electric field distribution, it can be understood that by not apodizing the second region A2 located between the two first regions A1 within the two busbars 21, the electric field distribution on both sides of the filter 100 along the second direction 002 is relatively uniform, thereby ensuring the improved operating performance and Q value of the filter 100.

[0124] Meanwhile, by adjusting the distribution of the first region A1 and the second region A2, the filter 100 of this application can, on the one hand, facilitate matching the different requirements of the filter 100 for working performance and Q value, and on the other hand, facilitate the fabrication of the filter 100 and reduce the manufacturing cost of the filter 100.

[0125] It is understood that in other embodiments, the number, distribution position, and size relationship of the first region A1 and the second region A2 may be different. For example, the number of the first region A1 and the second region A2 is one. This application does not impose any particular limitation on this.

[0126] In one embodiment, the lengths of the protrusions 211 within the second region A2 are equal. Since the ends of the protrusions 211 within the second region A2 are used to form a second fitting line L2, and the second fitting line L2 is a curve, it is understood that because the lengths of the protrusions 211 are equal, the line segments formed by the projection of the surfaces of the protrusions 211 onto the piezoelectric substrate 10 by the busbars 21 are also curves. That is, the busbars 21 are also apodized, thereby further adjusting the electric field distribution during the operation of the filter 100 and further improving the Q value of the filter 100.

[0127] Please refer to the above. Figure 12 The diagram shows a schematic representation of the surface structure of a filter 100 provided in one embodiment of this application.

[0128] like Figure 12 As shown, each electrode finger 22 located in the second region A2 includes two third sound velocity structures 33. One third sound velocity structure 33 is located at the fingertip of the electrode finger 22, and the other third sound velocity structure 33 is close to the side of the busbar 21 connected to the electrode finger 22. That is, in the second region A2, all electrode fingers 22 are provided with two third sound velocity structures 33 to adjust the electric field distribution at the fingertip of the second region A2, thereby making the electric field generated by the filter 100 of this application relatively uniform when it is working, and further improving the working performance and Q value of the filter 100 of this application.

[0129] In one embodiment, such as Figure 12 As shown, the electrode finger 22 in the first region A1 near the second region A2 is flush with the electrode finger 22 in the second region A2 near the first region A1. That is, two adjacent electrode fingers 22 in the first region A1 and the second region A2 are flush, so that the electric field between the first region A1 and the second region A2 is relatively uniform, thereby ensuring the electric field distribution when the filter 100 of this application is working and improving the Q value of the filter 100 of this application.

[0130] In one embodiment, the electrode finger 22 near the second region A2 within the first region A1 is designated as the first electrode finger 221. That is, the portion where the first fitting line L1 connects to the second region A2 is the peak or trough of the first fitting line L1. Correspondingly, the straight line formed by the fingertips of each electrode finger 22 within the second region A2 is tangent to the first fitting line L1, thereby enabling a smooth transition between the electric field in the first region A1 and the electric field in the second region A2. This ensures the electric field distribution during operation of the filter 100 of this application and improves the Q value of the filter 100.

[0131] Please refer to the above. Figure 13 The diagram shown is a top view of another structure of the filter 100 provided in one embodiment of this application.

[0132] like Figure 13 As shown, in the first region A1, in addition to the first electrode finger 221 and the second electrode finger 222, the other electrode fingers 22 also include two fourth sound speed structures 34. One of the fourth sound speed structures 34 is located at the fingertip of the electrode finger 22, and the other fourth sound speed structure 34 is close to one side of the bus bar 21 connected to the electrode finger 22.

[0133] That is, in the first region A1, all electrode fingers 22 are provided with two sound velocity structures to adjust the electric field distribution at the finger tips in the first region A1, thereby making the electric field generated by the filter 100 of this application relatively uniform when it is working, and further improving the working performance and Q value of the filter 100 of this application.

[0134] In this embodiment, the third sound speed structure 33 and the fourth sound speed structure 34 can be configured as follows: Figure 13 The extended electrode finger 22 shown is the fingertip of the electrode finger 22 and the side of the electrode finger 22 near the busbar 21. Alternatively, as shown... Figure 9 and Figure 10 The first sound velocity structure 31 is shown in the configuration shown. This application does not impose any particular restrictions on this configuration.

[0135] Please refer to the above. Figure 14 The diagram shown is another top view of the filter 100 provided in one embodiment of this application.

[0136] like Figure 14 As shown, each busbar 21 also includes a busbar body 212, a connector 213, and a conductive element 214. The busbar body 212 extends along the second direction 002 and along the first direction 001. The connector 213 and the conductive element 214 are located between the busbar body 212 and a plurality of electrode fingers 22. Each connector 213 is connected to a conductive element 214 and the busbar body 212. The extension direction of the conductive element 214 is parallel to the second direction 002. A protrusion 211 protrudes from the surface of the conductive element 214 facing the electrode finger 22. One end of each electrode finger 22 is connected to a busbar body 212 through a conductive element 214, and the other end is spaced apart from the protrusion 211 of another conductive element 214.

[0137] Specifically, the first busbar 21a is defined as including a first busbar body 2121, a first conductive element 2141, and a first connector 2131. The second busbar 21b is defined as including a second busbar body 2122, a second conductive element 2142, and a second connector 2132.

[0138] Along the first direction 001, a first conductive element 2141 and a first connector 2131 are provided between the first bus body 2121 and the electrode finger 22. The first connector 2131 connects the first conductive element 2141 and the first bus body 2121 to realize the conduction between the first conductive element 2141 and the first bus body 2121.

[0139] Along the first direction 001, a second conductive element 2142 and a second connector 2132 are provided between the second bus body 2122 and the electrode finger 22. The second connector 2132 is connected between the second conductive element 2142 and the second bus body 2122 to realize the conduction between the second conductive element 2142 and the second bus body 2122.

[0140] One end of the first electrode 22a is connected to a first conductive element 2141, and the other end is spaced apart from a second conductive element 2142. One end of the second electrode 22b is connected to a second conductive element 2142, and the other end is spaced apart from a first conductive element 2141.

[0141] In this embodiment, the conductive element 214 and the connector 213 are arranged to form a sound velocity region with different sound velocities between the electrode finger 22 and the bus body 212, thereby adjusting the sound field distribution on the surface of the piezoelectric substrate 10, which facilitates the improvement of the working performance and Q value of the filter 100 of this application.

[0142] exist Figure 14 In the illustration shown, the conductive element 214, the connector 213, and the electrode finger 22 are arranged in the same layer, and the conductive element 214, the connector 213, and the electrode finger 22 are made of the same material, so as to facilitate the fabrication of the conductive element 214, the connector 213, and the electrode finger 22 in the filter 100 of this application.

[0143] It is worth noting that the width of the conductive component 214 can be matched and set according to actual usage requirements. Figure 14 In the illustrated figures, the width dimensions of the conductive element 214, the connector 213, and the electrode finger 22 are all equal. In other embodiments, the width dimension of the conductive element 214 may not be equal to the width dimensions of the connector 213 and the electrode finger 22; this application does not impose any particular limitation on this.

[0144] In one embodiment, the connector 213, the conductive element 214, and the connected electrode finger 22 are integrated as a single unit. Specifically, in the process of fabricating the filter 100 of this application, the conductive element 214, the connector 213, and the electrode finger 22 can be integrally formed from the same material to simplify the fabrication process of the filter 100 of this application.

[0145] Please refer to the above. Figure 15 The diagram shown is a top view of the filter 100 provided in one embodiment of this application.

[0146] like Figure 15 As shown, each of the multiple electrode fingers 22 includes multiple electrode finger groups 40, and each electrode finger 22 is located within at most one electrode finger group 40. Along the second direction 002, the multiple electrode finger groups 40 are arranged at intervals. Each electrode finger group 40 includes two adjacent electrode fingers 22, and a connector 213 and a conductive member 214 arranged on both sides of the two electrode fingers 22 along the first direction 001. The projections of the two electrode fingers 22 onto the conductive member 214 along the first direction 001 are located on the conductive member 214. Any one of the two electrode fingers 22 is connected to one conductive member 214 and is spaced apart from the protrusion 211 of the other conductive member 214.

[0147] Specifically, for an electrode finger group 40, an electrode finger group 40 includes a first electrode 22a, a second electrode 22b, a first conductive element 2141, a second conductive element 2142, a first connector 2131, and a second connector 2132. It is understood that by providing multiple electrode finger groups 40, the filter 100 of this application allows the electrode finger groups 40 to be fabricated first during the fabrication process, which is beneficial to the fabrication of the filter 100.

[0148] It should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0149] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0150] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Those skilled in the art will understand that implementing all or part of the processes of the above embodiments, and making equivalent changes according to the claims of this utility model, still falls within the scope of this utility model.

Claims

1. A filter, characterized in that, include: The piezoelectric substrate, and two busbars and a plurality of electrode fingers disposed on the piezoelectric substrate, the busbars being spaced apart along a first direction and extending along a second direction, the plurality of electrode fingers being located between the two busbars, each electrode finger being connected to one of the busbars and spaced apart from the other busbar, and each electrode finger connected to different busbars being alternately arranged along the second direction, the second direction intersecting the first direction; Along the first direction, the busbar has a plurality of protrusions on the side facing the electrode finger. Each protrusion is aligned with and spaced apart from the electrode finger connected to another busbar. Among the electrode fingers connected to the busbar, at least a portion of the fingertip of the electrode finger is fitted to form a first fitting line, and the end of the protrusion near the side of the busbar is fitted to form a second fitting line. The functions satisfied by each of the first fitting lines and each of the second fitting lines are periodic functions.

2. The filter according to claim 1, characterized in that, The number of periods of the functions satisfied by the first and second fitted lines is less than or equal to 50.

3. The filter according to claim 1, characterized in that, At different locations in the second direction, the first fitted line and the second fitted line are spaced equally apart in the first direction.

4. The filter according to claim 1, characterized in that, The first fitted line satisfies a first function, which includes any one of a sine function, a cosine function, and an envelope function; and / or, the second fitted line satisfies a second function, which includes any one of a sine function, a cosine function, and an envelope function, wherein a and b are constants.

5. The filter according to claim 1, characterized in that, The first fitted line and the second fitted line are set to the same function; A fitting midline is formed between two adjacent first fitting lines. The fitting midline is equidistant from the first fitting lines on both sides. At the same position, the fitting midline is equidistant from the second fitting lines on both sides.

6. The filter according to claim 1, characterized in that, The first fitted line and the second fitted line are set to the same function; Wherein, a fitting midline is formed between two adjacent first fitting lines, and the distance difference between the fitting midline and the first fitting lines on both sides is less than or equal to λ, where λ is the sound wave period.

7. The filter according to any one of claims 1-6, characterized in that, Along the first direction, the electrode fingers are spaced apart from the busbars, and there is a first gap and a second gap between the electrode fingers and the busbars spaced apart from each other; Wherein, the electrode fingers corresponding to the first spacing and the second spacing are both first electrode fingers; Each of the first electrode fingers includes two first sound velocity structures, one of which is located at the fingertip of the first electrode finger spaced apart from the busbar, and the other of which is close to the busbar connected to the first electrode finger; wherein... The first sound velocity structures near the busbar side are fitted together with the fingertips of the other electrode fingers to form the first fitting line.

8. The filter according to claim 7, characterized in that, The electrode finger further includes a plurality of second electrode fingers, and along the second direction, the ratio of the distance between the central axis of each second electrode finger and the adjacent first electrode finger to one period of the first fitting line is less than or equal to 0.

125. Each second electrode finger includes two second acoustic structures, one of which is located at the tip of the second electrode finger, and the other is located near the busbar connected to that second electrode finger; wherein... Each of the adjacent first sound velocity structures and each of the second sound velocity structures of each of the busbars, in conjunction with the fingertips of the other electrode fingers, forms the first fitting line.

9. The filter according to claim 8, characterized in that, Along the second direction, the width dimension of each of the first sound velocity structures is greater than the width dimension of the first electrode finger to which the first sound velocity structure is connected, and the material of the first sound velocity structure is the same as the material of the first electrode finger; and / or, Along the second direction, the width dimension of each of the second sound velocity structures is greater than the width dimension of the second electrode finger to which the second sound velocity structure is connected, and the material of the second sound velocity structure is the same as the material of the second electrode finger.

10. The filter according to claim 8, characterized in that, Along the first direction, the filter includes an aperture size; along the second direction, the distance between the central axes of two adjacent electrode fingers is the finger spacing; and the ratio of the aperture size to the finger spacing is greater than or equal to 10.

11. The filter according to claim 10, characterized in that, The aperture size includes a maximum aperture size and a minimum aperture size. The ratio of the difference between the maximum aperture size and the minimum aperture size to the finger spacing is greater than or equal to 0.2 and less than or equal to 31.

12. The filter according to claim 7, characterized in that, The region between the two busbars includes a connected first region and a second region. There are two first regions along the second direction. The second region is located between the two first regions. The plurality of electrodes are distributed in each of the first regions and the second region. Among the electrode fingers connected to the busbar, the fingertips of the electrode fingers located in the first region are fitted to form the first fitting line, and the fingertips of the protrusions facing the electrode fingers in the first region are fitted to form the second fitting line; along the first direction, the lengths of the electrode fingers in the second region are equal and aligned with each other, and the lengths of the protrusions in the second region are equal.

13. The filter according to claim 12, characterized in that, Each of the electrode fingers located in the second region includes two third sound velocity structures, one of which is located at the tip of the electrode finger, and the other is located near the side of the busbar connected to the electrode finger.

14. The filter according to claim 12, characterized in that, The electrode finger in the first region that is close to the second region is flush with the electrode finger in the second region that is close to the first region.

15. The filter according to claim 12, characterized in that, The electrode finger in the first region that is close to the second region is the first electrode finger.

16. The filter according to any one of claims 1-6, characterized in that, Each of the busbars further includes a busbar body, a connector, and a conductive element. The busbar body extends along the second direction. Along the first direction, the connector and the conductive element are located between the busbar body and the plurality of electrode fingers. Each connector is connected to one of the conductive elements and the busbar body. The extension direction of the conductive element is parallel to the second direction. The protrusion is provided on the surface of the conductive element facing the electrode finger. Each of the electrodes has one end connected to a busbar via a conductive element, and the other end spaced apart from the protrusion of another conductive element.

17. The filter according to claim 16, characterized in that, Each of the plurality of electrode fingers includes a plurality of electrode finger groups, and each of the electrode fingers is located in at most one of the electrode finger groups. Along the second direction, the plurality of electrode finger groups are arranged at intervals. Each electrode finger group includes two adjacent electrode fingers, and a connector and a conductive element arranged on both sides of the two electrode fingers along a first direction. The projection of the two electrode fingers onto the conductive element along the first direction is located on the conductive element. Either of the two electrode fingers is connected to one of the conductive elements and spaced apart from the protrusion of the other conductive element.

18. A radio frequency front-end module, characterized in that, Includes the filter as described in any one of claims 1-17.

19. An electronic device, characterized in that, Includes the radio frequency front-end module as described in claim 18.

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