Acoustic resonator, filter, radio frequency chip and electronic equipment

Abstract

The invention provides an acoustic resonator, a filter, a radio frequency chip and electronic equipment, relates to the technical field of electronics, and aims to reduce the transverse vibration mode of the acoustic resonator. The acoustic resonator comprises an interdigital transducer and two reflectors, a plurality of first interdigital electrodes and a plurality of second interdigital electrodes of the interdigital transducer are alternately arranged along a first direction, each reflector comprises a plurality of reflecting electrodes arranged along the first direction, the reflecting electrodes comprise at least one first reflecting electrode, and the reflecting electrodes comprise at least one second reflecting electrode. The first reflection electrode comprises a first sub-electrode and a second sub-electrode, and a first gap is formed between the second ends of the first sub-electrode and the second sub-electrode; the distance between the second end of the first sub-electrode and the center line and the distance between the second ends, not connected with the first bus electrode, of the multiple first interdigital electrodes and the center line change periodically, and the distance between the second ends, not connected with the second bus electrode, of the multiple second interdigital electrodes and the center line change periodically. The acoustic resonator is used for reducing energy loss in the filtering process.

Description

Technical Field

[0001] This application relates to the field of electronic technology, and more particularly to an acoustic resonator, filter, radio frequency chip, and electronic device. Background Technology

[0002] Compared to traditional radio frequency (RF) filters, acoustic wave (AWF) filters offer numerous advantages, including high performance, high frequency selectivity, small size, and compatibility with semiconductor processes, making them widely used in mobile communication terminals. With the continuous upgrading of communication channel capacity, the increase in the number of communication frequency bands, and the shrinking frequency band spacing, acoustic filters will find even greater application in future mobile communications.

[0003] Acoustic filters can be composed of acoustic resonators, but acoustic resonators are prone to generating unexpected vibration modes, causing energy leakage, resulting in ripples in the passband of the acoustic filter, and reducing the filter's performance. Summary of the Invention

[0004] This application provides an acoustic resonator, filter, radio frequency chip, and electronic device for reducing the lateral vibration modes of the acoustic resonator, reducing energy leakage of the acoustic resonator, and improving the performance of the acoustic resonator.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, embodiments of this application provide an acoustic resonator, which includes a piezoelectric substrate, an interdigital transducer, and two reflectors. The interdigital transducer is disposed on the piezoelectric substrate and includes a plurality of first interdigital electrodes, a plurality of second interdigital electrodes, a first bus electrode, and a second bus electrode; the plurality of first interdigital electrodes and the plurality of second interdigital electrodes are located between the first bus electrode and the second bus electrode and are alternately arranged along a first direction; the first interdigital electrode includes a first end connected to the first bus electrode and a second end away from the first bus electrode, and the second interdigital electrode includes a first end connected to the second bus electrode and a second end away from the second bus electrode. Two reflectors are respectively disposed on opposite sides of the interdigital transducer in a first direction. The reflectors include a plurality of reflective electrodes arranged along the first direction, and the plurality of reflective electrodes include at least one first reflective electrode. The first reflective electrode includes a first sub-electrode and a second sub-electrode spaced apart in a second direction, the second direction being perpendicular to the first direction. The first sub-electrode includes a first end and a second end, and the second sub-electrode also includes a first end and a second end, with a first gap formed between the second end of the first sub-electrode and the second end of the second sub-electrode. The first end of the first sub-electrode and the first ends of the plurality of first interdigital electrodes are located on the same side of the centerline of the interdigital transducer. The distance from the second end of the first sub-electrode and the second ends of the plurality of first interdigital electrodes to the centerline of the interdigital transducer varies periodically, and the centerline is parallel to the first direction. The distance from the second ends of the plurality of second interdigital electrodes to the centerline also varies periodically.

[0007] Because the distances from the second ends of the multiple first interdigital electrodes to the center line change periodically, and the distances from the second ends of the multiple second interdigital electrodes to the center line also change periodically, the surface acoustic waves excited by the interdigital electrodes gradually weaken from the overlapping area of ​​the first and second interdigital electrodes towards both sides in the second direction, thereby suppressing the transverse vibration mode. Furthermore, since the second ends of the first and second sub-electrodes form a first gap, and this first gap is provided on the first reflecting electrode of the reflector, the first gap does not reflect surface acoustic waves along the first direction and randomly reflects surface acoustic waves propagating in directions other than the first direction caused by the second ends of the first interdigital electrodes. Simultaneously, the distances from the first gap and the second ends of the multiple first interdigital electrodes to the center line also change periodically. Therefore, the sound waves generated by the random reflection of the first gap can further cancel out the sound waves that gradually weaken outward from the overlapping area of ​​the first and second interdigital electrodes, thereby further suppressing the transverse vibration mode, reducing energy leakage of the acoustic resonator, and improving the performance of the acoustic resonator.

[0008] In one possible implementation of the first aspect, the periodic variation of the distances from the second ends of the plurality of first interdigital electrodes to the center line along the first direction is the same as the periodic variation of the distances from the second ends of the plurality of second interdigital electrodes to the center line. Thus, in the second direction, the surface acoustic waves excited by the interdigital electrodes gradually weaken to the same degree from the overlapping region of the interdigital electrodes outwards, balancing energy leakage on both sides.

[0009] In one possible implementation of the first aspect, the aperture of the interdigital transducer remains constant along the first direction; the aperture is the length by which adjacent first and second interdigital electrodes overlap in the second direction, which is perpendicular to the first direction. This ensures that the periodic variation of the distances from the second ends of the plurality of first interdigital electrodes to the center line is the same as the periodic variation of the distances from the second ends of the plurality of second interdigital electrodes to the center line.

[0010] In one possible implementation of the first aspect, the plurality of reflective electrodes further includes at least one second reflective electrode, the second reflective electrode comprising a third sub-electrode and a fourth sub-electrode spaced apart in a second direction; the third sub-electrode includes a first end and a second end, and the fourth sub-electrode also includes a first end and a second end; a second gap is formed between the second ends of the third sub-electrode and the second ends of the fourth sub-electrode; wherein the first end of the third sub-electrode and the first ends of the plurality of second interdigital electrodes are located on the same side of the centerline of the interdigital transducer, and the distance from the second end of the third sub-electrode and the second ends of the plurality of second interdigital electrodes to the centerline varies periodically. Thus, the sound waves generated by the reflection of surface acoustic waves not propagating in the first direction by the second gap can also cancel the sound waves that gradually weaken outward from the overlapping area of ​​the interdigital electrodes, thereby further canceling the surface acoustic waves generated by the second ends of the plurality of second interdigital electrodes and further suppressing the transverse vibration mode.

[0011] In one possible implementation of the first aspect, the first reflective electrode and the second reflective electrode are alternately arranged along a first direction. This allows the first gap formed on the first reflective electrode and the second gap formed on the second reflective electrode to also be alternately arranged, thereby maintaining the same periodic variation as the second ends of the first and second reflective electrodes. This increases the ability of the first gap to suppress lateral patterns generated at the second end of the first interdigital electrode, and increases the ability of the second gap to suppress lateral patterns generated at the second end of the second interdigital electrode.

[0012] In one possible implementation of the first aspect, the electrode closest to the reflector among the plurality of first interdigital electrodes and the plurality of second interdigital electrodes is the second interdigital electrode, and the electrode closest to the interdigital transducer among the plurality of reflective electrodes is the first reflective electrode; or, the electrode closest to the reflector among the plurality of first interdigital electrodes and the plurality of second interdigital electrodes is the first interdigital electrode, and the electrode closest to the interdigital transducer among the plurality of reflective electrodes is the second reflective electrode. This allows the spacing between the first gap of the first reflective electrode and the second end of the first interdigital electrode closest to it to be consistent with the spacing between the second ends of two adjacent first interdigital electrodes, thereby increasing the ability of the first gap to suppress lateral modes generated at the second end of the first interdigital electrode. Similarly, the ability of the second gap to suppress lateral modes generated at the second end of the second interdigital electrode can be increased.

[0013] In one possible implementation of the first aspect, the plurality of reflective electrodes further includes a third reflective electrode, which is continuously disposed in the second direction; the third reflective electrode is further away from the interdigital transducer than the first and second reflective electrodes. Thus, the third reflective electrode can increase the reflectivity of the reflector along the first direction and reduce energy leakage in the first direction.

[0014] In one possible embodiment of the first aspect, the interdigital transducer further includes a first transverse mode suppression structure, a second transverse mode suppression structure, a third transverse mode suppression structure, and a fourth transverse mode suppression structure. The first transverse mode suppression structure is disposed at the second end of the first interdigital electrode; the second transverse mode suppression structure is disposed between the first end and the second end of the first interdigital electrode; the third transverse mode suppression structure is disposed at the second end of the second interdigital electrode; and the fourth transverse mode suppression structure is disposed between the first end and the second end of the second interdigital electrode. The distances from the second end of the first interdigital electrode, the first transverse mode suppression structure, and the fourth transverse mode suppression structure to the center line vary periodically; the distances from the second transverse mode suppression structure and the third transverse mode suppression structure to the center line also vary periodically. Thus, by providing transverse mode suppression structures on the interdigital electrodes, and by periodically varying the distances of the transverse mode suppression structures to the center line, the transverse mode generated at the second end of the interdigital electrodes can be further suppressed.

[0015] In one possible embodiment of the first aspect, the reflector further includes a fifth transverse mode suppression structure and a sixth transverse mode suppression structure; the fifth transverse mode suppression structure is disposed at the second end of the first sub-electrode; the sixth transverse mode suppression structure is disposed on the portion of the first sub-electrode away from the second sub-electrode. The distances from the fifth, first, and fourth transverse mode suppression structures to the center line vary periodically; the distances from the sixth, second, and third transverse mode suppression structures to the center line also vary periodically. Thus, the fifth transverse mode suppression structure, whose distances to the center line follow a periodic variation pattern, can increase the ability to suppress transverse modes generated at the second end of the first interdigital electrode, and the sixth transverse mode suppression structure, whose distances to the center line follow a periodic variation pattern, can increase the ability to suppress transverse modes generated at the second end of the second interdigital electrode.

[0016] In one possible implementation of the first aspect, the second end of the first sub-electrode and the second ends of the plurality of first interdigital electrodes are located on a first envelope, and the second ends of the plurality of second interdigital electrodes are located on a second envelope; the first and second envelopes are graphs of a broken line function or a trigonometric function. Thus, since the first gap and the second ends of the plurality of first interdigital electrodes are located on the graph of the broken line function or trigonometric function, the distances from the first gap and the second ends of the plurality of first interdigital electrodes to the center line change periodically; similarly, the distances from the second ends of the plurality of second interdigital electrodes to the center line also change periodically.

[0017] In one possible implementation of the first aspect, the first and second envelopes are graphs of broken line functions, where the angle between any straight segment of the broken line function and the first direction ranges from 1° to 70°. This increases the effective area of ​​the acoustic resonator, helping to reduce its volume.

[0018] Secondly, this application provides a filter that includes an acoustic resonator according to any one of the first aspects.

[0019] Thirdly, this application provides a radio frequency chip, which includes a processor and a filter as described in the second aspect, with the processor connected to the filter.

[0020] Fourthly, this application provides an electronic device including a printed circuit board and the radio frequency chip described in the third aspect, the radio frequency chip being disposed on the printed circuit board.

[0021] The beneficial effects of the second to fourth aspects can be referred to the description in the first aspect, and will not be repeated here. Attached Figure Description

[0022] Figure 1 This is a top view schematic diagram of the acoustic resonator in related technologies;

[0023] Figure 2 For along Figure 1 Schematic diagram of the cross-sectional structure of line AA in the middle;

[0024] Figures 3-5 For some other possible routes Figure 1 Schematic diagram of the cross-sectional structure of line AA in the middle;

[0025] Figure 6 This is a schematic diagram of another acoustic resonator in related technologies;

[0026] Figure 7 This is a schematic diagram of the structure of another acoustic resonator in related technologies;

[0027] Figure 8 In order to be in Figure 6 Simulation diagram of energy distribution of acoustic resonators in the image;

[0028] Figure 9 This is a schematic diagram of another acoustic resonator in related technologies;

[0029] Figure 10 This is a schematic diagram of an acoustic resonator structure proposed in an embodiment of this application;

[0030] Figure 11 The diagram shows the admittance characteristics of the acoustic resonator proposed in this embodiment and the acoustic resonator structure of the conventional structure.

[0031] Figure 12 The image shows the quality factor curves of the acoustic resonator proposed in this embodiment and the acoustic resonator structure of the conventional structure.

[0032] Figures 13-31 Here are schematic diagrams of the structures of some other acoustic resonators proposed in the embodiments of this application;

[0033] Figure 32 This is a schematic diagram of a filter structure proposed in an embodiment of this application;

[0034] Figure 33 This is a schematic diagram of another filter structure proposed in an embodiment of this application;

[0035] Figure 34 This is a schematic diagram of another filter structure proposed in the embodiments of this application;

[0036] Figure 35 This is a schematic diagram of the structure of the electronic device proposed in the embodiments of this application. Detailed Implementation

[0037] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by those skilled in the art. The terms "first," "second," "third," and similar words used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of embodiments in this application, unless otherwise stated, "a plurality of" means two or more.

[0038] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0039] In the embodiments of this application, "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0040] First, in order to understand the present invention and compare it with the embodiments, a surface acoustic wave resonator as a comparative example will be described.

[0041] Please see Figures 1-2 , Figure 1 This is a top view schematic diagram of the acoustic resonator 10 in the related technology. Figure 2 It is along Figure 1 A schematic cross-sectional view of the AA line. The acoustic resonator 10 may include a piezoelectric substrate 300, an interdigital transducer (IDT) 100, and two reflectors 200. The interdigital transducer 100 and the two reflectors 200 may be disposed on the same surface of the piezoelectric substrate 300, with the interdigital transducer 100 disposed between the two reflectors 200. The piezoelectric substrate 300 may be made of a single-crystal or polycrystalline material with a piezoelectric effect, such as one or a combination of lithium tantalate (LiTaO3), lithium niobate (LiNbO3), quartz, aluminum nitride (AlN), zinc oxide (ZnO), and piezoelectric ceramic leadzirconate titanate (PZT).

[0042] The interdigital transducer 100 may include interdigital electrodes and busbars. The interdigital electrodes include multiple first interdigital electrodes 111 and multiple second interdigital electrodes 112, and the busbars include a first busbar 121 and a second busbar 122. Each of the multiple first interdigital electrodes 111 includes a first end and a second end, with the first end of each first interdigital electrode 111 connected to the first busbar 121. Similarly, each of the multiple second interdigital electrodes 112 also includes a first end and a second end, with the first end of each second interdigital electrode 112 connected to the second busbar 122. The multiple first interdigital electrodes 111 and multiple second interdigital electrodes 112 are arranged alternately. The interdigital electrodes may be made of highly conductive metals, such as aluminum (Al), tungsten (W), molybdenum (Mo), nickel (Ni), gold (Au), platinum (Pt), copper (Cu), titanium (Ti), silver (Ag), chromium (Cr), or an alloy of one or more of these metals. The interdigital electrodes may also be a multilayer stacked structure of multiple metals.

[0043] Two reflectors 200 are located on either side of the interdigital transducer 100 along the arrangement direction of the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112. Each reflector 200 may include a reflective electrode 210 and a reflector bus electrode 220. Exemplarily, the extension direction of the reflector bus electrode 220 may be the same as the extension direction of the bus electrode. A reflector 200 may include a plurality of reflective electrodes 210 and two reflector bus electrodes 220, with each end of each reflective electrode 210 connected to one of the two reflector bus electrodes 220. The reflector bus electrodes 220 of the reflector 200 may not be connected to other structures, i.e., the reflector 200 may be placed at a floating potential. Alternatively, the reflector bus electrodes 220 of the reflector 200 may be connected to a bus electrode; for example, one of the two reflector bus electrodes 220 may be connected to a bus electrode.

[0044] When the acoustic resonator 10 is operating, a radio frequency signal is input to the interdigital electrodes through the bus electrode. Due to the piezoelectric effect, the sound wave is excited and propagates in the piezoelectric substrate 300. When the surface acoustic wave propagates to the reflector 200, the reflector 200 reflects the surface acoustic wave. In this way, the reflector 200 confines the energy of the surface acoustic waves excited by the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 within the reflector 200.

[0045] In some embodiments, the piezoelectric substrate 300 can be a single-layer structure or a multi-layer structure. When the piezoelectric substrate 300 is a multi-layer structure, it is advantageous to reduce sound wave loss during propagation. For example, as... Figure 3As shown, the piezoelectric substrate 300 may include a piezoelectric layer 310 and a substrate layer 320. The piezoelectric layer 310 may be located above the substrate layer 320 and directly contact the interdigital transducer 100 and the reflector 200. The piezoelectric layer 310 may be made of a single-crystal or polycrystalline material with a piezoelectric effect. The thickness of the piezoelectric layer 310 may range from 0.1 times to 10 times the wavelength of the sound wave propagating in the acoustic resonator 10, for example, it may be 0.1 times, 1 time, 3 times, 5 times, 8 times, or 10 times. The substrate 320 may be made of silicon or other materials suitable for semiconductor processes. For example, as... Figure 4 As shown, the piezoelectric substrate 300 may include a piezoelectric layer 310, a substrate layer 320, and an acoustic reflection layer 330. The acoustic reflection layer 330 may be a multilayer structure, for example, the acoustic reflection layer 330 includes a first acoustic reflection layer and a second acoustic reflection layer.

[0046] In some implementations, such as Figure 5 As shown, a temperature compensation layer 340 can also be formed on the surface of the piezoelectric substrate 300 where the interdigital transducer 100 and reflector 200 are located. That is, a temperature compensation layer 340 is formed on the surface of the piezoelectric substrate 300 where the interdigital transducer 100 and reflector 200 are formed, covering the interdigital transducer 100 and reflector 200. The temperature compensation layer 340 can be made of silicon oxide (SiO2), and its thickness can range from 0.1 times to 10 times the wavelength of the sound wave propagating in the acoustic resonator 10, for example, 0.1 times, 1 time, 3 times, 5 times, 8 times, or 10 times. In this way, the temperature of the interdigital transducer 100 is compensated by the temperature compensation layer 340, reducing the impact of temperature changes on the excited sound wave caused by the interdigital electrodes.

[0047] However, the discontinuity at the ends of the interdigitated electrodes causes acoustic wave scattering, which easily excites transverse vibration modes (hereinafter referred to as transverse modes), resulting in ripple in the passband of the acoustic resonator 10 and reducing filter performance. Therefore, in order to achieve a high-performance acoustic filter, it is necessary to suppress the transverse modes of the acoustic resonator 10.

[0048] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of an acoustic resonator 10 in the related technology. Figure 6In the acoustic resonator 10, piston structures 120 are provided on multiple first interdigital electrodes 111 and multiple second interdigital electrodes 112 to suppress transverse modes. Each interdigital electrode has two piston structures 120. Specifically, one piston structure 120 on the first interdigital electrode 111 is located at the first end of the first interdigital electrode 111, and the other piston structure 120 is located between the first and second ends of the first interdigital electrode 111; similarly, one piston structure 120 on the second interdigital electrode 112 is located at the first end of the second interdigital electrode 112, and the other piston structure 120 is located between the first and second ends of the second interdigital electrode 112. Furthermore, the distance between the two piston structures 120 on the first interdigital electrode 111 is equal to the distance between the two piston structures 120 on the second interdigital electrode 112.

[0049] Please see Figure 7 , Figure 7 This is a schematic diagram of the structure of an acoustic resonator 10 in the related technology. Figure 7 In the acoustic resonator 10, hammer structures 130 are provided on multiple first interdigital electrodes 111 and multiple second interdigital electrodes 112 to suppress transverse modes. The hammer structures 130 are positioned on the interdigital electrodes in the same manner as the piston structures 120 are positioned on the interdigital electrodes.

[0050] Although incorporating piston and hammer structures on the interdigitated electrodes can achieve some lateral mode suppression, lateral modes can still be generated by the interdigitated electrodes. Please see [link to relevant documentation]. Figure 8 , Figure 8 This is a simulation diagram of the energy distribution of an acoustic resonator 10 with a piston structure on its interdigitated electrodes. Different horizontal and vertical axes correspond to different positions on the acoustic resonator 10. Figure 8 The distribution range of the interdigitated electrodes is 800–2400 on the horizontal axis and 150–250 on the vertical axis. The depth of the pattern indicates the energy level; for example, black represents energy 0, white represents energy 1, and energy 1 represents the highest energy in acoustic resonator 10. From Figure 8 As can be seen, some of the energy of the acoustic resonator 10 with the piston structure leaks from the left and right sides of the bus electrode to the side of the bus electrode away from the interdigitated electrode. In other words, the piston structure of the acoustic resonator 10 has a limited effect on suppressing the transverse mode.

[0051] Please see Figure 9 , Figure 9 This is a schematic diagram of the structure of an acoustic resonator 10 in related technologies. Figure 9In this process, apodization weighting is applied to the second ends of the plurality of first interdigital electrodes 111 of the acoustic resonator 10, and apodization weighting is also applied to the second ends of the plurality of second interdigital electrodes 112, so that the aperture of the acoustic resonator 10 gradually increases and then decreases in the direction of sound wave propagation. The aperture of the acoustic resonator 10 refers to the overlap length of adjacent first interdigital electrodes 111 and second interdigital electrodes 112 in the direction of interdigital electrode extension.

[0052] Although, Figure 9 The acoustic resonator 10 in the design has the effect of suppressing transverse modes, but the effective area of ​​the acoustic resonator 10 accounts for a small proportion of its total area. The effective area of ​​the acoustic resonator 10 refers to the overlapping region of the first interdigital electrode 111 and the second interdigital electrode 112. Therefore, to excite sufficient sound waves, the total area of ​​the acoustic resonator 10 needs to be increased, which is detrimental to miniaturization and also increases the manufacturing cost of the acoustic resonator 10.

[0053] For this purpose, please see Figure 10 This application provides an acoustic resonator 10 that can suppress the lateral propagation mode of sound waves. This acoustic resonator 10 is coupled with... Figures 1-5 The difference in the acoustic resonator shown lies in the arrangement of the interdigital transducer 100 and the reflector 200. That is, the acoustic resonator 10 proposed in this embodiment may include a piezoelectric substrate, an interdigital transducer 100, and a reflector 200, with the interdigital transducer 100 and reflector 200 disposed on the piezoelectric substrate; and the piezoelectric substrate may refer to, for example... Figures 2-4 The piezoelectric substrate 300 shown is disposed thereon; similarly, the acoustic resonator 10 proposed in the embodiments of this application may also include, as shown in the example. Figure 5 The temperature compensation layer 340 is shown.

[0054] The following describes in detail the configuration of the interdigital transducer 100 and reflector 200 of the acoustic resonator 10 proposed in the embodiments of this application. For ease of explanation, the following configuration is established: Figure 10 The diagram shows a Cartesian coordinate system, where the Y-direction is the extension direction of the interdigital electrodes of the interdigital transducer 100, and the X-direction is perpendicular to the Y-direction. Understandably, the X-direction can be the same as the desired propagation direction of the surface acoustic wave excited by the interdigital electrodes; that is, the desired propagation direction of the surface acoustic wave is perpendicular to the extension direction of the interdigital electrodes.

[0055] The interdigital transducer 100 of the acoustic resonator 10 may include a plurality of first interdigital electrodes 111, a plurality of second interdigital electrodes 112, a first bus electrode 121, and a second bus electrode 122.

[0056] A plurality of first interdigital electrodes 111 and a plurality of second interdigital electrodes 112 are disposed between a first bus electrode 121 and a second bus electrode 122, and are arranged alternately along the X direction. Each first interdigital electrode 111 includes a first end and a second end, wherein the first end of the first interdigital electrode 111 is connected to the first bus electrode, and the second end of the first interdigital electrode 111 is located away from the first bus electrode 121. Similarly, each second interdigital electrode 112 also includes a first end and a second end, wherein the first end of the second interdigital electrode 112 is connected to the second bus electrode, and the second end of the second interdigital electrode 112 is located away from the second bus electrode. Understandably, any adjacent first interdigital electrodes 111 and second interdigital electrodes 112 overlap each other in the Y direction, and the length of the overlap is equal to the aperture of the interdigital transducer 100.

[0057] The plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 can be elongated strips extending in the Y direction and can be fabricated using semiconductor processes. The plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 can be referenced in the accompanying drawings. Figures 1-2 Material of the interdigitated electrode.

[0058] The first bus electrode 121 and the second bus electrode 122 may extend in the X direction. For example, the first bus electrode 121 and the second bus electrode 122 may be elongated strips that are parallel to each other. The first bus electrode 121 may be integrally disposed with a plurality of first interdigital electrodes 111, and the second bus electrode 122 may be integrally disposed with a plurality of second interdigital electrodes 112.

[0059] The acoustic resonator 10 may include two reflectors 200, which are respectively disposed on opposite sides of the interdigital transducer 100 in the X direction, that is, the interdigital transducer 100 is disposed between the two reflectors 200.

[0060] The reflector 200 may include a plurality of reflective electrodes 210 arranged along the X direction. The plurality of reflective electrodes 210 includes at least one first reflective electrode 211, which includes a first sub-electrode 2111 and a second sub-electrode 2112 spaced apart in the Y direction. Understandably, both the first sub-electrode 2111 and the second sub-electrode 2112 extend in the Y direction and can extend along the same straight line. That is, the first reflective electrode 211 does not extend continuously and has an interruption. The first sub-electrode 2111 of the first reflective electrode 211 includes a first end and a second end, and the second sub-electrode 2112 of the first reflective electrode 211 also includes a first end and a second end, forming a first gap 2113 between the second end of the first sub-electrode 2111 and the second end of the second sub-electrode 2112. The first end of the first sub-electrode 2111 and the first ends of the plurality of first interdigital electrodes 111 are located on the same side of the centerline R of the interdigital transducer 100, which is along the X direction. In other words, the centerline R refers to the centerline of the interdigital transducer 100 in the Y direction. For example, when the interdigital transducer 100 is symmetrical about a straight line parallel to the X direction, this straight line is the axis of symmetry of the interdigital transducer 100, and the centerline R can be this axis of symmetry.

[0061] For example, the reflector 200 may include a third bus electrode 223 and a fourth bus electrode 224, with a plurality of reflective electrodes 210 disposed between the third bus electrode 223 and the fourth bus electrode 224. The third bus electrode 223 may extend in the same direction as the first bus electrode 121, and the fourth bus electrode 224 may extend in the same direction as the second bus electrode 122. For example, the first bus electrode 121, the third bus electrode 223, and the fourth bus electrode 224 all extend in the X direction, and in the X direction, the first bus electrode 121 is aligned with the third bus electrode 223, and the second bus electrode 122 is aligned with the fourth bus electrode 224. Furthermore, the distance between the third bus electrode 223 and the fourth bus electrode 224 may be equal to the distance between the first bus electrode 121 and the second bus electrode 122. The third bus electrode 223 and the fourth bus electrode 224 can be placed at a floating potential, and at least one of the third bus electrode 223 and the fourth bus electrode 224 can also be connected to the first bus electrode 121 and / or the second bus electrode 122.

[0062] The positional relationship between the second end of the first sub-electrode 2111 and the second end of the first interdigital electrode 111 may be related. Please continue reading. Figure 10The first end of the first sub-electrode 2111 may be located on the same side of the center line R as the first ends of the plurality of first interdigital electrodes 111. Furthermore, the distances from the second ends of the first sub-electrode 2111 and the plurality of first interdigital electrodes 111 to the center line R change periodically; that is, according to the arrangement order of the first sub-electrode 2111 and the plurality of first interdigital electrodes 111 along the X direction, the distances from the second ends of the first sub-electrode 2111 and the plurality of first interdigital electrodes 111 to the center line R change periodically in sequence. For example, within one cycle, the distances from the second ends of the first sub-electrode 2111 and the plurality of first interdigital electrodes 111 to the center line R gradually increase and then gradually decrease.

[0063] Similarly, the distance from the second end of the plurality of second interdigital electrodes 122 to the center line R also changes periodically. For example, within one cycle, the distance from the second end of the plurality of second interdigital electrodes 122 to the center line R gradually increases and then gradually decreases.

[0064] Thus, because the distances from the second ends of the multiple first interdigital electrodes 111 to the center line R change periodically, and the distances from the second ends of the multiple second interdigital electrodes 122 to the center line R also change periodically, the surface acoustic waves excited by the interdigital electrodes gradually weaken in the Y direction from the overlapping area of ​​the interdigital electrodes outwards, thereby suppressing the transverse vibration mode of the surface acoustic waves. Simultaneously, the second ends of the first sub-electrode 2111 and the second sub-electrode form a first gap 2113. Therefore, when the surface acoustic waves propagating in the X direction reach the reflector 200, the first gap 2113 does not reflect the surface acoustic waves in the X direction, but randomly reflects the surface acoustic waves propagating in the non-X direction caused by the second ends of the first interdigital electrodes 111, thus changing the reflectivity of the reflector 200. Furthermore, since the distances from the second end of the first sub-electrode 2111 and the second ends of the multiple first interdigital electrodes 111 to the center line R also change periodically, the sound waves generated by the reflection of surface acoustic waves that do not propagate along the X direction by the first gap 2113 can further cancel the sound waves that gradually weaken outward from the overlapping area of ​​the interdigital electrodes, thereby further suppressing the transverse vibration mode.

[0065] Please see Figure 11 and Figure 12 , Figure 11 This is an admittance characteristic curve, where the horizontal axis represents the normalized frequency, the vertical axis represents the normalized admittance, and the solid line represents the normalized admittance provided in the embodiments of this application. Figure 10 The admittance characteristic curve of the acoustic resonator 10 shown is illustrated by the dotted line. Figure 1 The admittance characteristic curve of the acoustic resonator 10 with the conventional structure is shown. Figure 11In the figure, the two admittance characteristic curves almost completely overlap, the resonant frequency Fs is about 0.76 and the anti-resonant frequency Fp is about 0.80. That is to say, the improved acoustic resonator 10 implemented in this application will not affect the admittance characteristics of the acoustic resonator 10. Figure 12 This is a quality factor curve, with the horizontal axis representing the normalized frequency and the vertical axis representing the normalized quality factor. The acoustic resonator 10 primarily operates within the resonant frequency Fs and anti-resonant frequency Fp. Within this range, a higher quality factor is better, and a smoother change in quality factor with frequency is also better. Figure 12 It can be seen that in the frequency range of 0.76 to 0.77, the quality factor of the acoustic resonator 10 provided in this application embodiment is slightly lower than that of the traditional structure, but the quality factor of the acoustic resonator 10 provided in this application embodiment changes more smoothly with frequency; in the frequency range of 0.77 to 0.80, the quality factor of the acoustic resonator 10 provided in this application embodiment is higher than that of the traditional structure, and the quality factor of the acoustic resonator 10 provided in this application embodiment changes more smoothly with frequency, while the acoustic resonator 10 of the traditional structure has multiple abrupt change points in this frequency range. Figure 12 The abrupt change point (indicated by the middle arrow) corresponds to the frequency at which energy leakage and severe transverse acoustic modes occur in the acoustic resonator 10. Therefore, it is evident that the acoustic resonator 10 provided in this embodiment has better performance than conventional acoustic resonators 10.

[0066] In some embodiments, the periodic variation of the distances from the second ends of the plurality of first interdigital electrodes 111 to the center line R along the X direction is the same as the periodic variation of the distances from the second ends of the plurality of second interdigital electrodes 112 to the center line R. The periodic variation may include the magnitude of the period. For example, Figure 10In this context, the period T is the length of the eight interdigitated electrodes arranged in the X direction. The periodic variation can also include the sequential changes in the distance from the second end of the same type of interdigitated electrode to the center line R within one period. For example, within one period of the periodic variation of the first interdigitated electrode 111, there are four first interdigitated electrodes 111. Along the X direction, the distances from the second end of the first interdigitated electrode 111 to the center line R are 1, 2, 2, and 1, respectively, resulting in a change value of 1, 0, and 1. Similarly, within one period of the periodic variation of the second interdigitated electrode 112, there are also four second interdigitated electrodes 112. Along the X direction, the distances from the second end of the second interdigitated electrode 112 to the center line R are 3, 4, 4, and 3, respectively, resulting in a change value of 1, 0, and 1. Thus, the variation of multiple second interdigitated electrodes 112 within one period is the same as the variation of multiple first interdigitated electrodes 111 within one period. The periodic variation can also include situations where the distance between any two adjacent first interdigital electrodes 111 and the reflective electrode 210 in the X direction is equal. Consequently, the surface acoustic waves excited by the interdigital electrodes gradually weaken to the same degree in the Y direction from the overlapping area of ​​the interdigital electrodes outwards.

[0067] For example, along the X direction, the aperture of the interdigital transducer 100 remains constant, as previously described, and is the length by which two adjacent interdigital electrodes overlap in the Y direction. Understandably, because the first interdigital electrode 111 and the second interdigital electrode 112 are alternately arranged in the X direction, two adjacent interdigital electrodes are respectively the first interdigital electrode 111 and the second interdigital electrode 112. This ensures that the periodic variation of the distance from the second end of the plurality of first interdigital electrodes 111 to the center line R is the same as the periodic variation of the distance from the second end of the plurality of second interdigital electrodes 112 to the center line R.

[0068] In some embodiments, the plurality of reflective electrodes 210 further includes at least one second reflective electrode 212, the second reflective electrode 212 including a third sub-electrode 2121 and a fourth sub-electrode 2122 spaced apart in the Y direction. Understandably, both the third sub-electrode 2121 and the fourth sub-electrode 2122 extend in the Y direction and may extend along the same straight line. That is, the second reflective electrode 212 does not extend continuously and has an interruption. The third sub-electrode 2121 of the second reflective electrode 212 includes a first end and a second end, and the second sub-electrode 2122 of the second reflective electrode 212 also includes a first end and a second end, forming a second gap 2123 between the second end of the third sub-electrode 2121 and the second end of the fourth sub-electrode 2122. Similarly, the first end of the third sub-electrode 2121 and the first ends of the plurality of second interdigital electrodes 112 are located on the same side of the centerline R, and the distances from the second ends of the third sub-electrode 2121 and the second ends of the plurality of second interdigital electrodes 112 to the centerline R vary periodically. For example, within one cycle, the distance from the second end of the third sub-electrode 2121 and the second ends of the plurality of second interdigital electrodes 112 to the center line R exhibits a periodic change of gradually increasing and then gradually decreasing. Thus, the sound waves generated by the reflection of surface acoustic waves (SAW) that do not propagate along the X direction by the second gap 2123 formed by the second end of the third sub-electrode 2121 can also counteract the gradually weakening sound waves from the overlapping area of ​​the interdigital electrodes outwards, thereby further counteracting the SAW generated by the second ends of the plurality of second interdigital electrodes 112 and further suppressing the transverse vibration mode.

[0069] For example, the first reflective electrode 211 and the second reflective electrode 212 are alternately arranged along the X direction. In this way, the first gap 2113 formed on the first reflective electrode 211 and the second gap 2123 formed on the second reflective electrode 212 can also be alternately arranged, so as to maintain the same periodic variation as the second end of the first reflective electrode 211 and the second end of the second reflective electrode 212.

[0070] For example, the electrode closest to the reflector 200 among the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 is the second interdigital electrode 112, and the electrode closest to the interdigital transducer 100 among the plurality of reflective electrodes is the first reflective electrode 211 (e.g., ...). Figure 10The first reflective electrode 212 in the reflector 200 on the left. In this way, the spacing between the first reflective electrode 212 and the first interdigital electrode 111 closest to it can be consistent with the spacing between any two adjacent first interdigital electrodes 111 among the plurality of first interdigital electrodes 111. The spacing refers to the number of other electrodes arranged between two adjacent electrodes of the same type, or the number of other electrodes arranged between the first gap 2113 and the first interdigital electrode 111 closest to it, or the number of other electrodes arranged between the second gap 2123 and the second interdigital electrode 112 closest to it.

[0071] For example, the electrode closest to the reflector 200 among the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 is the first interdigital electrode 111, and the electrode closest to the interdigital transducer 100 among the plurality of reflective electrodes is the second reflective electrode 112 (e.g., ...). Figure 10 (The second reflective electrode 112 in the reflector 200 on the left). In this way, the spacing between the second reflective electrode 212 and the second interdigital electrode 112 closest to it can be consistent with the spacing between two adjacent second interdigital electrodes 112 among the plurality of second interdigital electrodes 121.

[0072] Please see Figure 13 In some embodiments, the plurality of reflective electrodes further includes a third reflective electrode 213, which may be continuously arranged in a direction intersecting the X direction, for example, the third reflective electrode 213 may be continuously arranged in the Y direction. Continuous arrangement means that the third reflective electrode has no gaps. For example, when the reflector 200 includes a third bus electrode 223 and a fourth bus electrode 224, the third reflective electrode 213 is disposed between and connects the third bus electrode 223 and the fourth bus electrode 224. Thus, the third reflective electrode 223 can increase the reflectivity of the reflector 200 along the X direction and reduce energy leakage in the X direction.

[0073] For example, the third reflective electrode 213 is further away from the interdigital transducer 100 than the first reflective electrode 211 and / or the second reflective electrode 212. That is, the first reflective electrode 211 and / or the second reflective electrode 212 are disposed between the third reflective electrode 213 and the interdigital transducer 100. In this way, random reflection of surface acoustic waves in the non-X direction can occur in a region closer to the interdigital transducer 100, increasing random reflection to suppress transverse vibration modes and reducing energy leakage of surface acoustic waves in the X direction.

[0074] In some embodiments, since the distances from the second end of the first sub-electrode 2111 and the second ends of the plurality of first interdigital electrodes 111 to the center line R change periodically, the curve formed by the second end of the first sub-electrode 2111 and the second ends of the plurality of first interdigital electrodes 111 can be a graph of a periodic function. For example, the curve formed by the second end of the first sub-electrode 2111 and the second ends of the plurality of first interdigital electrodes 111 can be a first envelope line L1 formed by the second end of the first sub-electrode 2111 and the second ends of the plurality of first interdigital electrodes 111, and this first envelope line L1 is a graph of a periodic function. The envelope line refers to a virtual line formed by connecting the second end of the first sub-electrode 2111 and the second ends of the plurality of interdigital electrodes, and the second end of the first sub-electrode 2111 and the second ends of the plurality of interdigital electrodes are all located on the same side of this virtual line and in contact with it. In this case, it can also be considered that the second end of the first sub-electrode 2111 and the second ends of the plurality of interdigital electrodes are all located on this virtual line.

[0075] Similarly, since the distances from the plurality of second interdigital electrodes 112 to the center line R change periodically, the curve formed based on the second ends of the plurality of second interdigital electrodes 112 can also be a graph of a periodic function. Exemplarily, this curve is also a second envelope L2 formed based on the second ends of the plurality of second interdigital electrodes 112. When the reflector 200 includes a second reflective electrode 212, the second end of the third sub-electrode 2111 and the second ends of the plurality of second interdigital electrodes 112 together form the second envelope L2.

[0076] Understandably, since the first envelope L1 formed by the second ends of the multiple first interdigital electrodes 111 is a periodic function, the line connecting the multiple maxima in this periodic function is a straight line parallel to the X direction. Similarly, since the second envelope L2 formed by the second ends of the multiple second interdigital electrodes 112 is also a periodic function, the line connecting the multiple minima of this periodic function is also a straight line parallel to the X direction. In this case, the aforementioned center line R can also be a straight line equidistant from the aforementioned two straight lines.

[0077] For example, the second envelope L2 can be such as Figure 10 and Figure 13 The graph of the broken line function shown can also be, for example, Figure 14 and Figure 15 The graph of the trigonometric functions is shown. Figure 14 and Figure 15 The difference in the acoustic resonator 10 is that Figure 15 The reflector 200 of the acoustic resonator 10 includes a third reflective electrode 213. When the first envelope L1 and the second envelope L2 are graphs of piecewise linear functions, the angle between any straight line segment of the piecewise linear function and the X direction ranges from 1° to 70°. For example, Figure 13 In the middle, the angle between the second envelope L2 and the X direction. The angles can be 1°, 10°, 25°, 45°, 60°, 70°, etc. This increases the effective area of ​​the interdigital transducer 100; at the same time, it makes the first gap 2113 reflect surface acoustic waves propagating in the non-X direction.

[0078] Please refer to the following: Figure 10 and Figure 16 In some embodiments, the acoustic resonator 10 may include a transverse mode suppression structure. The transverse mode suppression structure may be disposed on the interdigital transducer 100. In this case, the transverse mode suppression structure may include a first transverse mode suppression structure 131, a second transverse mode suppression structure 132, a third transverse mode suppression structure 133, and a fourth transverse mode suppression structure 134. The first transverse mode suppression structure 131 is disposed at the second end of the first interdigital electrode 111; the second transverse mode suppression structure 132 is disposed between the first end and the second end of the first interdigital electrode 111; the third transverse mode suppression structure 133 is disposed at the second end of the second interdigital electrode 112; and the fourth transverse mode suppression structure 134 is disposed between the first end and the second end of the second interdigital electrode 112. Furthermore, the distances from the second end of the first sub-electrode 2111, the first transverse mode suppression structure 131, and the fourth transverse mode suppression structure 134 to the center line R change periodically. For example, the distances from the second end of the first sub-electrode 2111, the first transverse mode suppression structure 131, and the fourth transverse mode suppression structure 134 to the center line R exhibit a periodic change of gradually increasing and then gradually decreasing. For example, when the second ends of the plurality of first interdigital electrodes 111 are also used to form the first envelope line L1, that is, when the second end of the first sub-electrode 2111 and the first transverse mode suppression structure 131 are located on the first envelope line L1, the fourth transverse mode suppression structure 134 is also located on the first envelope line L1. Similarly, when the second ends of the plurality of second interdigital electrodes 112 are located on the second envelope line L2, that is, when the third transverse mode suppression structure 133 is located on the second envelope line L2, the second transverse mode suppression structure 132 is also located on the second envelope line L2. If the reflector 200 includes a second reflective electrode 212, then the second end of the third sub-electrode 2121 of the second reflective electrode 212 is also located on the second envelope line L2. In this way, the transverse modes of surface acoustic waves can be suppressed by the transverse mode suppression structure, thereby reducing energy leakage.

[0079] For example, please see Figure 16 and Figure 17 Transverse mode suppression structures can be, for example, Figure 16 The piston structure shown can be formed by increasing the thickness of the interdigitated electrodes at the location of the transverse mode suppression structure; the transverse mode suppression structure can also be, for example... Figure 17 The hammerhead structure shown can be formed by increasing the size of the interdigitated electrode in the X direction at the location of the transverse mold suppression structure.

[0080] Similarly, when the curve formed by the second end of the first sub-electrode 2111 and the second ends of the plurality of first interdigital electrodes 111 is a periodic function, a transverse mode suppression structure can also be provided on the interdigital transducer 100. For example... Figure 18 As shown, the interdigital transducer 100 includes a piston structure; as Figure 19 As shown, the interdigital transducer 100 includes a hammer structure.

[0081] Similarly, please see Figures 20-23 When the reflector 200 includes a third reflective electrode 213, the interdigital transducer 100 may also include a transverse mode suppression structure. For example... Figure 20 and Figure 21 The interdigital transducer 100 includes a piston structure; such as Figure 22 and Figure 23 The interdigitated transducer 100 includes a hammerhead structure.

[0082] Please refer to the following: Figure 16 and Figure 24 Transverse mode suppression structures can also be disposed on the reflector 200. In this case, the transverse mode suppression structure may include a fifth transverse mode suppression structure 235 and a sixth transverse mode suppression structure 236. The fifth transverse mode suppression structure 235 and the sixth transverse mode suppression structure 236 can be disposed on the first reflective electrode 211. The fifth transverse mode suppression structure 235 can be disposed at the second end of the first sub-electrode 2111, so that the distances from the fifth transverse mode suppression structure 235, the first transverse mode suppression structure 131, and the fourth transverse mode suppression structure 134 to the center line R change periodically. For example, the distances from the fifth transverse mode suppression structure 235, the first transverse mode suppression structure 131, and the fourth transverse mode suppression structure 134 to the center line R change periodically, gradually increasing and then gradually decreasing. The sixth transverse mode suppression structure 236 can be disposed between the first end and the second end of the first sub-electrode 2112, and the sixth transverse mode suppression structure 236, the second transverse mode suppression structure 132, and the third transverse mode suppression structure 133 change periodically. For example, the distances from the sixth transverse mode suppression structure 236, the second transverse mode suppression structure 132, and the third transverse mode suppression structure 133 to the center line R exhibit a periodic change of gradually increasing and then gradually decreasing.

[0083] Similarly, please see Figure 24 and Figure 25 Transverse mode suppression structures can be, for example, Figure 24 The piston structure shown can also be, for example, Figure 15 The hammerhead structure shown.

[0084] Similarly, when the curve formed by the second end of the first sub-electrode 2111 and the second ends of the plurality of first interdigital electrodes 111 is a periodic function, a transverse mode suppression structure can also be provided on the interdigital transducer 100. For example... Figure 26 As shown, the interdigital transducer 100 includes a piston structure; as Figure 27 As shown, the interdigital transducer 100 includes a hammer structure.

[0085] Similarly, please see Figures 28-31 When the reflector 200 includes a third reflective electrode 213, a transverse mode suppression structure can also be provided on the reflector 200. Simultaneously, the transverse mode suppression structure can also be provided on the interdigital transducer 100, such as... Figure 28 and Figure 29 The interdigital transducer 100 includes a piston structure; such as Figure 30 and Figure 31 The interdigitated transducer 100 includes a hammerhead structure.

[0086] Furthermore, this application embodiment also provides a filter 1, which includes any possible acoustic resonator 10 proposed in the foregoing embodiments of this application. The filter 1 can be, for example, a low-pass acoustic filter, a high-pass acoustic filter, a band-pass acoustic filter, a band-stop acoustic filter, or an active acoustic filter.

[0087] In some implementations, please refer to Figure 32 , Figure 32 This is a schematic diagram of the structure of a filter 1, which is a ladder type filter (LTF).

[0088] Filter 1 may include an input terminal 2, an output terminal 3, a ground terminal 4, and a plurality of resonators 10. At least two acoustic resonators 10 are connected in series to form a path connecting the input terminal 2 and the output terminal 3, and at least one acoustic resonator 10 is disposed between the path and the ground terminal 4, for example, one acoustic resonator 10 is disposed between the two acoustic resonators 10 connected in series and the ground terminal 4. Input terminal 2 is used to input the signal to be filtered, and output terminal 3 is used to output the filtered signal.

[0089] In some implementations, please refer to Figure 33 , Figure 33 The diagram shows the structure of another filter 1, which is a double-mode saw filter (DMS). Filter 1 may include an input terminal 2, an output terminal 3, and an acoustic resonator 10. The acoustic resonator 10 may include at least two interdigital transducers 100.

[0090] For example, the acoustic resonator 10 may include two interdigital transducers 100. The two interdigital transducers 100 may be either of the interdigital transducers 100 described in the foregoing embodiments, along the extension direction of the interdigital electrodes (e.g., Figure 11The image (in the Y direction) is divided into two interdigital transducers 100. Thus, both interdigital transducers 100 are positioned between the two reflectors 200. Understandably, the two interdigital transducers 100 have similar structures. The number of interdigital electrodes included in the two interdigital transducers 100 may be the same or different. Input terminal 2 can be connected to the bus electrode of one interdigital transducer 100, and output terminal 3 can be connected to the bus electrode of the other interdigital transducer 100. The bus electrode connected to input terminal 2 and the bus electrode connected to output terminal 3 may be located on the same side or different sides of the bus electrode. The bus electrode of the interdigital transducer 100 not connected to input terminal 2 or output terminal 3 may be grounded.

[0091] For example, please see Figure 34 , Figure 34 This is a schematic diagram of another filter 1. The filter 1 includes three interdigital transducers 100. The three interdigital transducers 100 are arranged sequentially between two reflectors 200. Similarly, the three interdigital transducers 100 can be derived from one of the interdigital transducers 100 in the aforementioned embodiment along the extension direction of the interdigital electrode (e.g., ...). Figure 11 The circuit (in the Y direction) is divided into three interdigital transducers 100. The bus electrode of the middle interdigital transducer 100 can be connected to input terminal 2, and the two interdigital transducers 100 on either side can be connected to output terminal 3. The bus electrode connected to input terminal 2 and the bus electrode connected to output terminal 3 can be located on the same side or different sides of the interdigital transducers. The bus electrodes of the interdigital transducers 100 that are not connected to input terminal 2 or output terminal 3 can be grounded.

[0092] Please see Figure 35 This application also provides an electronic device 5, which can be, for example, a mobile phone, tablet computer, personal digital assistant (PDA), television, smart wearable products (e.g., smartwatches, smart bracelets), virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, rechargeable small household appliances (e.g., soymilk makers, robot vacuum cleaners), drones, radar, aerospace equipment, and vehicle-mounted equipment, as well as communication equipment such as wireless network cards, wireless routers, wireless transceiver modules, or communication base stations. This application does not impose any special limitations on the specific form of the electronic device.

[0093] Electronic device 5 may include a system-on-chip (SOC) 7, an RF chip 8, etc., disposed on a printed circuit board (PCB). The PCB is used to carry the SOC 7, RF chip 8, etc., and is connected to them. The RF chip 8 may include a filter 1, a processor 9, etc. The filter 1 is an important part of RF signal processing, used to allow signals of a specific frequency to pass while blocking signals of other frequencies. The processor 9 is connected to the filter 1 and is used to process various signals, for example, signals of a specific frequency that can pass through the filter 1.

[0094] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An acoustic resonator, characterized in that, include: piezoelectric substrate; An interdigital transducer, disposed on the piezoelectric substrate, includes a plurality of first interdigital electrodes, a plurality of second interdigital electrodes, a first bus electrode, and a second bus electrode. The plurality of first interdigital electrodes and the plurality of second interdigital electrodes are located between the first bus electrode and the second bus electrode and are alternately arranged along a first direction. The first interdigital electrode includes a first end connected to the first bus electrode and a second end away from the first bus electrode. The second interdigital electrode includes a first end connected to the second bus electrode and a second end away from the second bus electrode. Two reflectors are respectively disposed on opposite sides of the interdigital transducer in the first direction. Each reflector includes a plurality of reflective electrodes arranged along the first direction. The plurality of reflective electrodes includes at least one first reflective electrode. The first reflective electrode includes a first sub-electrode and a second sub-electrode spaced apart in a second direction perpendicular to the first direction. The first sub-electrode includes a first end and a second end, and the second sub-electrode also includes a first end and a second end. A first gap is formed between the second end of the first sub-electrode and the second end of the second sub-electrode. Wherein, the first end of the first sub-electrode and the first ends of the plurality of first interdigital electrodes are located on the same side of the center line of the interdigital transducer, and the distance from the second end of the first sub-electrode and the second ends of the plurality of first interdigital electrodes to the center line changes periodically, and the center line is parallel to the first direction; the distance from the second ends of the plurality of second interdigital electrodes to the center line also changes periodically.

2. The acoustic resonator as described in claim 1, characterized in that, Along the first direction, the periodic variation of the distance from the second end of the plurality of first interdigital electrodes to the center line is the same as the periodic variation of the distance from the second end of the plurality of second interdigital electrodes to the center line.

3. The acoustic resonator as described in claim 2, characterized in that, Along the first direction, the aperture of the interdigital transducer remains unchanged; the aperture is the length by which adjacent first and second interdigital electrodes overlap in a second direction, which is perpendicular to the first direction.

4. The acoustic resonator as described in any one of claims 1 to 3, characterized in that, The plurality of reflective electrodes further includes at least one second reflective electrode, the second reflective electrode including a third sub-electrode and a fourth sub-electrode spaced apart in the second direction; The third sub-electrode includes a first end and a second end, and the fourth sub-electrode also includes a first end and a second end; a second gap is formed between the second end of the third sub-electrode and the second end of the fourth sub-electrode; The first end of the third sub-electrode and the first ends of the plurality of second interdigital electrodes are located on the same side of the center line of the interdigital transducer, and the distance from the second end of the third sub-electrode and the second ends of the plurality of second interdigital electrodes to the center line varies periodically.

5. The acoustic resonator as described in claim 4, characterized in that, The first reflective electrode and the second reflective electrode are alternately arranged along the first direction.

6. The acoustic resonator as described in claim 4 or 5, characterized in that, The electrode closest to the reflector among the plurality of first interdigital electrodes and the plurality of second interdigital electrodes is the second interdigital electrode, and the electrode closest to the interdigital transducer among the plurality of reflective electrodes is the first reflective electrode; or, The electrode closest to the reflector among the plurality of first interdigital electrodes and the plurality of second interdigital electrodes is the first interdigital electrode, and the electrode closest to the interdigital transducer among the plurality of reflective electrodes is the second reflective electrode.

7. The acoustic resonator as described in any one of claims 4 to 6, characterized in that, The plurality of reflective electrodes further includes a third reflective electrode, which is continuously disposed in the second direction; The third reflective electrode is further away from the interdigital transducer than the first and second reflective electrodes.

8. The acoustic resonator as described in any one of claims 1 to 7, characterized in that, The interdigital transducer further includes: The first transverse mode suppression structure is disposed at the second end of the first interdigital electrode; The second transverse mode suppression structure is disposed between the first end and the second end of the first interdigital electrode. The third transverse mode suppression structure is disposed at the second end of the second interdigital electrode; The fourth transverse mode suppression structure is disposed between the first end and the second end of the second interdigital electrode; The distances from the second end of the first sub-electrode, the first transverse mode suppression structure, and the fourth transverse mode suppression structure to the center line vary periodically. The distances from the second transverse mode suppression structure and the third transverse mode suppression structure to the center line change periodically.

9. The acoustic resonator as described in claim 8, characterized in that, The reflector also includes: The fifth transverse mode suppression structure is located at the second end of the first sub-electrode; The sixth transverse mode suppression structure is disposed on the portion of the first sub-electrode that is far from the second sub-electrode; The distances from the fifth transverse mode suppression structure, the first transverse mode suppression structure, and the fourth transverse mode suppression structure to the center line vary periodically. The distances from the sixth transverse mode suppression structure, the second transverse mode suppression structure, and the third transverse mode suppression structure to the center line change periodically.

10. The acoustic resonator according to any one of claims 1 to 9, characterized in that, The second end of the first sub-electrode and the second ends of the plurality of first interdigital electrodes are located on the first envelope, and the second ends of the plurality of second interdigital electrodes are located on the second envelope; The first envelope and the second envelope are graphs of broken line functions or trigonometric functions.

11. The acoustic resonator as claimed in claim 10, characterized in that, The first envelope and the second envelope are graphs of a broken line function, and the angle between any straight line segment of the broken line function and the first direction is in the range of 1° to 70°.

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

13. A radio frequency chip, characterized in that, It includes a processor and a filter as described in claim 12, wherein the processor is connected to the filter.

14. An electronic device, characterized in that, It includes a printed circuit board and a radio frequency chip as described in claim 13, wherein the radio frequency chip is disposed on the printed circuit board.

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