Acoustic resonator, wave filter, radio frequency chip, and electronic device

Abstract

The present application relates to the technical field of electronics, and provides an acoustic resonator, a wave filter, a radio frequency chip, and an electronic device, for use in reducing lateral vibration modes 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 in a first direction; each reflector comprises a plurality of reflective electrodes arranged in the first direction; the plurality of reflective electrodes include at least one first reflective electrode; the first reflective electrode comprises a first sub-electrode and a second sub-electrode, and a first gap is formed between respective second ends of the first sub-electrode and the second sub-electrode; the distances from the second ends of the first sub-electrodes and from the second ends of the plurality of first interdigital electrodes that are not connected to a first busbar electrode to a center line vary periodically, and the distances from the second ends of the plurality of second interdigital electrodes that are not connected to a second busbar electrode to the center line vary periodically. The acoustic resonator is used for reducing energy loss during wave filtering.

Description

Acoustic resonator, filter, radio frequency chip and electronic device

[0001] The present application claims priority from the Chinese patent application No. 202411126927.X filed on August 15, 2024, and entitled "Acoustic resonator, filter, radio frequency chip and electronic device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of electronics, and in particular to an acoustic resonator, filter, radio frequency chip and electronic device. BACKGROUND

[0003] Compared with traditional radio frequency filters, acoustic wave filters (AWF) have high performance, high frequency selectivity, small size, compatibility with semiconductor processes and many other characteristics, and are widely used in mobile communication terminals. With the continuous upgrading of communication channel capacity, the number of communication frequency bands increases, and the frequency band interval becomes smaller. Acoustic wave filters will have greater applications in future mobile communications.

[0004] The acoustic resonator can be included in the acoustic filter unit, but the acoustic resonator is prone to produce vibration modes other than expected, resulting in energy leakage, causing the passband of the acoustic filter to produce ripples, and reducing the performance of the filter. SUMMARY

[0005] Embodiments of the present application provide an acoustic resonator, filter, radio frequency chip and electronic device for reducing the lateral vibration mode of the acoustic resonator, reducing the energy leakage of the acoustic resonator, and improving the performance of the acoustic resonator.

[0006] To achieve the above-mentioned purpose, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, an acoustic resonator is provided. The acoustic resonator 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. Each of the first interdigital electrodes includes a first end connected to the first bus electrode and a second end away from the first bus electrode. Each of the second interdigital electrodes includes a first end connected to the second bus electrode and a second end away from the second bus electrode. The two reflectors are respectively disposed on opposite sides of the interdigital transducer along the first direction. Each of the reflectors includes a plurality of reflection electrodes arranged along the first direction. The plurality of reflection electrodes includes at least one first reflection electrode. The first reflection electrode includes a first sub-electrode and a second sub-electrode spaced apart along a second direction perpendicular to the first direction. The first sub-electrode includes a first end and a second end. 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. The first end of the first sub-electrode and the first ends of the plurality of first interdigital electrodes are located on a same side of a center line of the interdigital transducer. The second end of the first sub-electrode and the second ends of the plurality of first interdigital electrodes periodically vary in distance to the center line of the interdigital transducer. The center line is parallel to the first direction. The second ends of the plurality of second interdigital electrodes periodically vary in distance to the center line.

[0008] Due to the periodic variation in distance of the second ends of the plurality of first interdigital electrodes to the center line and the periodic variation in distance of the second ends of the plurality of second interdigital electrodes to the center line, surface acoustic waves excited by the interdigital electrodes gradually weaken from a region where the first interdigital electrodes and the second interdigital electrodes overlap to both sides along the second direction, thereby suppressing a transverse vibration mode. In addition, since the second end of the first sub-electrode and the second end of the second sub-electrode form the first gap, the first reflection electrode of the reflector is provided with the first gap. The first gap does not reflect surface acoustic waves along the first direction and randomly reflects surface acoustic waves caused by the second ends of the first interdigital electrodes that propagate in directions other than the first direction. Meanwhile, the first gap and the second ends of the plurality of first interdigital electrodes to the center line also periodically vary in distance. Therefore, the sound waves randomly reflected by the first gap can further cancel the sound waves that gradually weaken from the region where the first interdigital electrodes and the second interdigital electrodes overlap to the outside, thereby further suppressing the transverse vibration mode, reducing energy leakage of the acoustic resonator, and improving performance of the acoustic resonator.

[0009] In a possible implementation of the first aspect, the periodic variation of the distance from the second end of the first plurality of interdigital electrodes to the center line is the same as the periodic variation of the distance from the second end of the second plurality of interdigital electrodes to the center line in the first direction. In this way, the degree of weakening of the surface acoustic wave excited by the interdigital electrodes gradually decreases from the area where the interdigital electrodes overlap to the outside in the second direction, balancing the energy leakage on both sides.

[0010] In a possible implementation of the first aspect, the aperture of the interdigital transducer remains unchanged in the first direction; the aperture is the length of the adjacent first interdigital electrode and second interdigital electrode overlapping each other in the second direction, and the second direction is perpendicular to the first direction. In this way, the periodic variation of the distance from the second end of the first plurality of interdigital electrodes to the center line can be ensured to be the same as the periodic variation of the distance from the second end of the second plurality of interdigital electrodes to the center line.

[0011] In a possible implementation of the first aspect, the plurality of reflective electrodes further comprises at least one second reflective electrode, the second reflective electrode comprises a third sub-electrode and a fourth sub-electrode arranged at intervals in the second direction; the third sub-electrode comprises a first end and a second end, and the fourth sub-electrode also comprises 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; wherein the first end of the third sub-electrode and the first end of the plurality of second interdigital electrodes are located on the same side of the center line of the interdigital transducer, and the second end of the third sub-electrode and the second end of the plurality of second interdigital electrodes periodically vary in distance from the center line. In this way, the sound wave reflected by the second gap due to the surface acoustic wave not propagating in the first direction can also offset the sound wave gradually weakening from the area where the interdigital electrodes overlap to the outside, so as to further offset the surface acoustic wave generated by the second end of the plurality of second interdigital electrodes, and further suppress the transverse vibration mode.

[0012] In a possible implementation of the first aspect, the first reflective electrode and the second reflective electrode are arranged alternately in the first direction. In this way, the first gap formed in the first reflective electrode and the second gap formed in the second reflective electrode can also be arranged alternately, so as to keep the same periodic variation of the second end of the first reflective electrode and the second end of the second reflective electrode, and further increase the ability of the first gap to suppress the transverse mode generated by the second end of the first interdigital electrode, and increase the ability of the second gap to suppress the transverse mode generated by the second end of the second interdigital electrode.

[0013] In a possible implementation manner of the first aspect, one of the plurality of first interdigital electrodes and the plurality of second interdigital electrodes closest to the reflector is the second interdigital electrode, and one of the plurality of reflective electrodes closest to the interdigital transducer is the first reflective electrode; or, one of the plurality of first interdigital electrodes and the plurality of second interdigital electrodes closest to the reflector is the first interdigital electrode, and one of the plurality of reflective electrodes closest to the interdigital transducer is the second reflective electrode. In this way, the spacing between the first gap of the first reflective electrode and the second end of the first interdigital electrode closest to the first reflective electrode can be consistent with the spacing between the second ends of two adjacent first interdigital electrodes of the plurality of first interdigital electrodes, thereby increasing the ability of the first gap to suppress the transverse mode generated by the second end of the first interdigital electrode. Similarly, the ability of the second gap to suppress the transverse mode generated by the second end of the second interdigital electrode can be increased.

[0014] In a possible implementation manner of the first aspect, the plurality of reflective electrodes further includes a third reflective electrode, the third reflective electrode being arranged continuously in the second direction; the third reflective electrode being farther away from the interdigital transducer than the first reflective electrode and the second reflective electrode. In this way, the third reflective electrode can increase the reflectivity of the reflector in the first direction and reduce energy leakage in the first direction.

[0015] In a possible implementation manner 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 arranged at the second end of the first interdigital electrode; the second transverse mode suppression structure is arranged between the first end and the second end of the first interdigital electrode; the third transverse mode suppression structure is arranged at the second end of the second interdigital electrode; and the fourth transverse mode suppression structure is arranged between the first end and the second end of the second interdigital electrode. The distance from the center line of the second end of the first interdigital electrode, the first transverse mode suppression structure, and the fourth transverse mode suppression structure varies periodically; and the distance from the center line of the second transverse mode suppression structure and the third transverse mode suppression structure varies periodically. In this way, the transverse mode suppression structures are arranged on the interdigital electrodes, and the distance from the center line of the transverse mode suppression structures varies periodically, thereby further suppressing the transverse mode generated by the second end of the interdigital electrode.

[0016] In a possible implementation 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 arranged on the second end of the first sub-electrode; and the sixth transverse mode suppression structure is arranged on the part of the first sub-electrode away from the second sub-electrode. The fifth transverse mode suppression structure, the first transverse mode suppression structure, and the fourth transverse mode suppression structure periodically change in distance to the center line; and the sixth transverse mode suppression structure, the second transverse mode suppression structure, and the third transverse mode suppression structure periodically change in distance to the center line. In this way, the fifth transverse mode suppression structure that changes in distance to the center line in a periodic manner can increase the ability to suppress the transverse mode generated at the second end of the first interdigital electrode, and the sixth transverse mode suppression structure that changes in distance to the center line in a periodic manner can increase the ability to suppress the transverse mode generated at the second end of the second interdigital electrode.

[0017] In a possible implementation of the first aspect, the second end of the first sub-electrode and the second end of the plurality of first interdigital electrodes are located on a first envelope line, and the second end of the plurality of second interdigital electrodes are located on a second envelope line; the first envelope line and the second envelope line are a graph of a broken line function or a trigonometric function. In this way, the first gap and the second end of the plurality of first interdigital electrodes are located on the graph of the broken line function or the trigonometric function, so that the distance of the first gap and the second end of the plurality of first interdigital electrodes to the center line changes periodically; similarly, the distance of the second end of the plurality of second interdigital electrodes to the center line also changes periodically.

[0018] In a possible implementation of the first aspect, the first envelope line and the second envelope line are a graph of a broken line function, and the angle between any straight line segment of the broken line function and the first direction ranges from 1° to 70°. In this way, the effective area of the acoustic resonator can be increased, which helps to reduce the volume of the acoustic resonator.

[0019] In a second aspect, the present application provides a filter including the acoustic resonator of any one of the first aspect.

[0020] In a third aspect, the present application provides a radio frequency chip including a processor and the filter of the second aspect, wherein the processor is connected to the filter.

[0021] In a fourth aspect, the present application provides an electronic device including a printed circuit board and the radio frequency chip of the third aspect, wherein the radio frequency chip is arranged on the printed circuit board.

[0022] The beneficial effects of the second aspect to the fourth aspect can be referred to the description of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is a top view of an acoustic resonator in the related art;

[0024] Fig. 2 is a schematic diagram of a cross-sectional structure along line A-A in Fig. 1 ;

[0025] Figs. 3-5 are schematic diagrams of other possible cross-sectional structures along line A-A in Fig. 1 ;

[0026] Fig. 6 is a schematic diagram of a structure of another acoustic resonator in the related art;

[0027] Fig. 7 is a schematic diagram of a structure of yet another acoustic resonator in the related art;

[0028] Fig. 8 is an energy distribution simulation diagram of the acoustic resonator in Fig. 6;

[0029] Fig. 9 is a schematic diagram of a structure of still another acoustic resonator in the related art;

[0030] Fig. 10 is a schematic diagram of a structure of an acoustic resonator according to an embodiment of the present application;

[0031] Fig. 11 is a diagram of a conductance characteristic curve of an acoustic resonator according to an embodiment of the present application and a conventional acoustic resonator structure;

[0032] Fig. 12 is a diagram of a quality factor curve of an acoustic resonator according to an embodiment of the present application and a conventional acoustic resonator structure;

[0033] Figs. 13-31 are schematic diagrams of structures of other acoustic resonators according to embodiments of the present application;

[0034] Fig. 32 is a schematic diagram of a structure of a filter according to an embodiment of the present application;

[0035] Fig. 33 is a schematic diagram of a structure of another filter according to an embodiment of the present application;

[0036] Fig. 34 is a schematic diagram of a structure of still another filter according to an embodiment of the present application;

[0037] Fig. 35 is a schematic diagram of a structure of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] Unless otherwise defined, technical and scientific terms used in the present application shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in the description of the application herein and the claims that follow is not intended to be limiting of the application. Thus, use of the terms "first", "second", "third", and the like in the description of the application herein and the claims that follow is merely to identify components of various embodiments, and is not intended to or should be construed to special sequential or chronological order. As well, use of terms such as "top", "bottom", "front", "back", "leading" and "trailing" are made for purposes of ease of description to orient one skilled in the art, and are in no way intended to restrict the scope of the application. Similarly, "an" should be understood to mean "one or more"; i.e. at least one.

[0039] In the embodiments of the present application, the word "exemplary" or "for example" is used to mean "an example of" or "an example, only. Any embodiment or design solution described in the embodiments of the present application as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or design solutions. Rather, the use of "exemplary" or "for example" is intended to present concepts in a particular manner.

[0040] In the embodiments of the present application, "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0041] First, in order to understand the present application and compare with the embodiments, the surface acoustic wave resonator as a comparative example is described.

[0042] Please refer to FIG. 1 and FIG. 2, FIG. 1 is a top view structural schematic diagram of an acoustic resonator 10 in the related art, and FIG. 2 is a sectional view structural schematic diagram along the line A-A in FIG. 1. The acoustic resonator 10 can include a piezoelectric substrate 300, an interdigital transducer (IDT) 100 and two reflectors 200. The interdigital transducer 100 and the two reflectors 200 can be disposed on the same surface of the piezoelectric substrate 300, and the interdigital transducer 100 is disposed between the two reflectors 200. The piezoelectric substrate 300 can be made of a single crystal or polycrystalline material having a piezoelectric effect, for example, it can be a combination of one or more of lithium tantalate (LiTaO3), lithium niobate (LiNbO3), quartz (Quartz), aluminum nitride (AlN), zinc oxide (ZnO), piezoelectric ceramic lead zirconate titanate (PZT).

[0043] The interdigital transducer 100 can include interdigital electrodes including a plurality of first interdigital electrodes 111 and a plurality of second interdigital electrodes 112, and bus bars including a first bus bar 121 and a second bus bar 122. The plurality of first interdigital electrodes 111 includes first ends and second ends, and the first ends of the first interdigital electrodes 111 are connected to the first bus bar 121. The plurality of second interdigital electrodes 112 also includes first ends and second ends, and the first ends of the second interdigital electrodes 112 are connected to the second bus bar 122. The plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 are alternately arranged in sequence. The interdigital electrodes can be made of a metal having good electrical conductivity, such as an alloy of one or more metals selected from the group consisting of aluminum (Al), tungsten (W), molybdenum (Mo), nickel (Ni), gold (Au), platinum (Pt), copper (Cu), titanium (Ti), silver (Ag), and chromium (Cr). The interdigital electrodes can also be a multi-layer stacked structure of multiple metals.

[0044] The two reflectors 200 are arranged on both sides of the interdigital transducer 100 along the direction in which the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 are arranged. The reflectors 200 can include reflection electrodes 210 and reflector bus bars 220. Exemplarily, the extension direction of the reflector bus bars 220 can be the same as the extension direction of the bus bars. One reflector 200 can include a plurality of reflection electrodes 210 and two reflector bus bars 220, and both ends of each reflection electrode 210 are connected to the two reflector bus bars 220, respectively. The reflector bus bars 220 of the reflector 200 can not be connected to other structures, i.e., the reflector 200 is in a floating state. The reflector bus bars 220 of the reflector 200 can also be connected to the bus bars, for example, one of the two reflector bus bars 220 is connected to the bus bar.

[0045] When the acoustic resonator 10 is in operation, a radio frequency signal is input to the interdigital electrodes through the bus bars, and due to the piezoelectric effect, acoustic waves are excited and propagated in the piezoelectric substrate 300. When the surface acoustic waves propagate to the reflectors 200, the reflectors 200 reflect the surface acoustic waves. In this way, the reflectors 200 confine the energy of the surface acoustic waves excited by the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 between the reflectors 200.

[0046] 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 the loss of the acoustic wave during propagation. For example, as shown in FIG. 3, the piezoelectric substrate 300 can include a piezoelectric layer 310 and a substrate layer 320, the piezoelectric layer 310 can be located above the substrate layer 320 and directly contact the IDT 100 and the reflector 200, the piezoelectric layer 310 can be made of a single crystal or polycrystalline material having a piezoelectric effect, and the thickness of the piezoelectric layer 310 can range from 0.1 times to 10 times the wavelength of the acoustic wave propagating in the acoustic resonator 10, for example, 0.1 times, 1 times, 3 times, 5 times, 8 times, or 10 times. The substrate 320 can be made of silicon or other materials suitable for semiconductor processes. For example, as shown in FIG. 4, the piezoelectric substrate 300 can include a piezoelectric layer 310, a substrate layer 320, and an acoustic reflection layer 330, the acoustic reflection layer 330 can be a multi-layer structure, for example, the acoustic reflection layer 330 includes a first acoustic reflection layer and a second acoustic reflection layer.

[0047] In some embodiments, as shown in FIG. 5, the surface of the piezoelectric substrate 300 on which the IDT 100 and the reflector 200 are disposed can also be provided with a temperature compensation layer 340, that is, the temperature compensation layer 340 is formed on the surface of the piezoelectric substrate 300 on which the IDT 100 and the reflector 200 are formed, and the temperature compensation layer 340 covers the IDT 100 and the reflector 200. The temperature compensation layer 340 can be made of silicon oxide (SiO2), and the thickness of the temperature compensation layer 340 can range from 0.1 times to 10 times the wavelength of the acoustic wave propagating in the acoustic resonator 10, for example, 0.1 times, 1 times, 3 times, 5 times, 8 times, or 10 times. In this way, the temperature of the IDT 100 is compensated by the temperature compensation layer 340, reducing the influence of temperature changes on the excited acoustic wave by the interdigital electrode.

[0048] However, the discontinuity at the end of the interdigital electrode can cause scattering of the acoustic wave, easily exciting a transverse vibration mode (hereinafter referred to as a transverse mode), causing ripples in the passband of the acoustic resonator 10, and reducing the performance of the filter. Therefore, in order to achieve a high-performance acoustic wave filter, it is necessary to suppress the transverse mode of the acoustic resonator 10.

[0049] Please refer to FIG. 6, which is a structural diagram of an acoustic resonator 10 in the related art. In FIG. 6, piston structures 120 are arranged on the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 of the acoustic resonator 10 to suppress the transverse mode. Two piston structures 120 are arranged on each interdigital electrode. Specifically, one piston structure 120 on the first interdigital electrode 111 is arranged at the first end of the first interdigital electrode 111, and the other piston structure 120 is arranged between the first end and the second end of the first interdigital electrode 111; one piston structure 120 on the second interdigital electrode 112 is arranged at the first end of the second interdigital electrode 112, and the other piston structure 120 is arranged between the first end and the second end of the second interdigital electrode 112. Moreover, 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.

[0050] Please refer to FIG. 7, which is a structural diagram of an acoustic resonator 10 in the related art. In FIG. 7, hammer structures 130 are arranged on the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 of the acoustic resonator 10 to suppress the transverse mode. The arrangement positions of the hammer structures 130 on the interdigital electrodes are the same as those of the piston structures 120.

[0051] Although the arrangement of the piston structures and the hammer structures on the interdigital electrodes can achieve a certain effect of suppressing the transverse mode, the interdigital electrodes still generate the transverse mode. Please refer to FIG. 8, which is an energy distribution simulation diagram of the acoustic resonator 10 with the piston structures arranged on the interdigital electrodes. In FIG. 8, different points corresponding to different horizontal coordinates and vertical coordinates represent different positions on the acoustic resonator 10. The range of the interdigital electrodes in FIG. 8 is 800-2400 for the horizontal coordinate and 150-250 for the vertical coordinate. The darkness of the pattern represents the energy level, for example, black represents 0 energy, white represents 1 energy, and 1 energy represents the highest energy in the acoustic resonator 10. As can be seen from FIG. 8, part of the energy of the acoustic resonator 10 with the piston structures arranged thereon leaks from the left and right sides of the bus electrode to the side of the bus electrode away from the interdigital electrodes, that is, the acoustic resonator 10 with the piston structures arranged thereon has a limited effect of suppressing the transverse mode.

[0052] Please refer to FIG. 9, which is a structural diagram of an acoustic resonator 10 in the related art. In FIG. 9, the second ends of the plurality of first interdigital electrodes 111 of the acoustic resonator 10 are apodized, and the second ends of the plurality of second interdigital electrodes 112 are also apodized, so that the aperture of the acoustic resonator 10 gradually increases and then decreases in the propagation direction of the acoustic wave. The aperture of the acoustic resonator 10 refers to the overlapping length of the adjacent first interdigital electrode 111 and the second interdigital electrode 112 in the extension direction of the interdigital electrode.

[0053] Although the acoustic resonator 10 in FIG. 9 has the effect of suppressing the lateral mode, the proportion of the effective area of the acoustic resonator 10 to the total area of the acoustic resonator 10 is small, wherein the effective area of the acoustic resonator 10 refers to the area where the first interdigital electrode 111 and the second interdigital electrode 112 overlap. Therefore, in order to excite sufficient acoustic waves, it is necessary to increase the total area of the acoustic resonator 10, which is not conducive to miniaturization and increases the manufacturing cost of the acoustic resonator 10.

[0054] For this purpose, referring to FIG. 10, the embodiment of the present application proposes an acoustic resonator 10 which can suppress the lateral propagation mode of acoustic waves. The acoustic resonator 10 is different from the acoustic resonator shown in FIGS. 1-5 in the arrangement of the interdigital transducer 100 and the reflector 200. That is, the acoustic resonator 10 proposed by the embodiment of the present application can include a piezoelectric substrate, an interdigital transducer 100 and a reflector 200, and the interdigital transducer 100 and the reflector 200 are arranged on the piezoelectric substrate; and the piezoelectric substrate can be arranged with reference to the piezoelectric substrate 300 shown in FIGS. 2-4; similarly, the acoustic resonator 10 proposed by the embodiment of the present application can also include a temperature compensation layer 340 as shown in FIG. 5.

[0055] The arrangement of the interdigital transducer 100 and the reflector 200 of the acoustic resonator 10 proposed by the embodiment of the present application will be described in detail below. For ease of description, a rectangular coordinate system as shown in FIG. 10 is established, wherein 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. It can be understood that 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.

[0056] The interdigital transducer 100 of the acoustic resonator 10 can 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.

[0057] The plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 are arranged between the first bus electrode 121 and the second bus electrode 122 and are alternately arranged along the X direction. The 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 121, and the second end of the first interdigital electrode 111 is away from the first bus electrode 121. Similarly, the second interdigital electrode 112 also includes a first end and a second end, the first end of the second interdigital electrode 112 is connected to the second bus electrode 122, and the second end of the second interdigital electrode 112 is away from the second bus electrode 122. It can be understood that any adjacent first interdigital electrode 111 and second interdigital electrode 112 overlap each other in the Y direction, and the length of the overlap is the aperture of the interdigital transducer 100.

[0058] The plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 can be in a long strip shape extending in the Y direction, and can be prepared by a semiconductor process. The plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 can use the same material as the interdigital electrodes in FIGS. 1-2.

[0059] The first bus electrode 121 and the second bus electrode 122 can extend in the X direction, for example, the first bus electrode 121 and the second bus electrode 122 are long strips parallel to each other. The first bus electrode 121 can be integrally provided with the plurality of first interdigital electrodes 111, and the second bus electrode 122 can be integrally provided with the plurality of second interdigital electrodes 112.

[0060] The acoustic resonator 10 can include two reflectors 200, which are respectively arranged on opposite sides of the interdigital transducer 100 in the X direction, that is, the interdigital transducer 100 is arranged between the two reflectors 200.

[0061] The reflector 200 can include a plurality of reflection electrodes 210 arranged in the X direction. The plurality of reflection electrodes 210 includes at least one first reflection electrode 211, and the first reflection electrode 211 includes a first sub-electrode 2111 and a second sub-electrode 2112 arranged at intervals in the Y direction. It can be understood that the first sub-electrode 2111 and the second sub-electrode 2112 can both extend in the Y direction, and the first sub-electrode 2111 and the second sub-electrode 2112 can extend along the same straight line. That is, the first reflection electrode 211 does not continuously extend, and there is an interruption. The first sub-electrode 2111 of the first reflection electrode 211 includes a first end and a second end, and the second sub-electrode 2112 of the first reflection electrode 211 also includes a first end and a second end, and a first gap 2113 is formed between the second end of the first sub-electrode 2111 and the second end of the second sub-electrode 2112. Among them, the first end of the first sub-electrode 2111 and the first end of the plurality of first interdigital electrodes 111 are located on the same side of the center line R of the interdigital transducer 100, and the center line R is along the X direction. That is, the center line R refers to the center line of the interdigital transducer 100 in the Y direction. Exemplarily, when the interdigital transducer 100 is symmetrical about a straight line parallel to the X direction, the straight line is the symmetry axis of the interdigital transducer 100, and the center line R can be the symmetry axis.

[0062] Exemplarily, the reflector 200 can include a third bus electrode 223 and a fourth bus electrode 224, and the plurality of reflective electrodes 210 is disposed between the third bus electrode 223 and the fourth bus electrode 224. The third bus electrode 223 can extend in the same direction as the first bus electrode 121, and the fourth bus electrode 224 can 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. In addition, the distance between the third bus electrode 223 and the fourth bus electrode 224 can 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 in 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.

[0063] The positional relationship between the second end of the first sub-electrode 2111 and the second end of the first interdigital electrode 111 can have relevance. Please continue to refer to FIG. 10, the first end of the first sub-electrode 2111 can be located on the same side of the center line R as the first end of the plurality of first interdigital electrodes 111. In addition, the distance from the second end of the first sub-electrode 2111 and the second end of the plurality of first interdigital electrodes 111 to the center line R changes periodically, that is, according to the arrangement order of the first sub-electrode 2111 and the plurality of first interdigital electrodes 111 in the X direction, the distance from the second end of the first sub-electrode 2111 and the second end of the plurality of first interdigital electrodes 111 to the center line R changes periodically in turn. Exemplarily, in one period, the distance from the second end of the first sub-electrode 2111 and the second end of the plurality of first interdigital electrodes 111 to the center line R gradually increases and then gradually decreases.

[0064] Similarly, the distance from the second end of the plurality of second interdigital electrodes 122 to the center line R also changes periodically. Exemplarily, in one period, the distance from the second end of the plurality of second interdigital electrodes 122 to the center line R also gradually increases and then gradually decreases.

[0065] Thus, due to the periodic variation of the distance between the second end of the first interdigital electrode 111 and the center line R, the distance between the second end of the second interdigital electrode 122 and the center line R also varies periodically, so the surface acoustic wave excited by the interdigital electrode gradually weakens in the Y direction from the area where the interdigital electrodes overlap to the outside, thereby the transverse vibration mode of the surface acoustic wave can be inhibited. Meanwhile, the second end of the first sub-electrode 2111 and the second end of the second sub-electrode form a first gap 2113, so when the surface acoustic wave propagating in the X direction reaches the reflector 200, the first gap 2113 does not reflect the surface acoustic wave propagating in the X direction, and randomly reflects the surface acoustic wave propagating in the non-X direction caused by the second end of the first interdigital electrode 111, thereby changing the reflectivity of the reflector 200. Because the distance between the second end of the first sub-electrode 2111 and the second end of the first interdigital electrode 111 also varies periodically, the sound wave reflected by the first gap 2113 to the surface acoustic wave propagating in the non-X direction can further cancel the sound wave gradually weakening from the area where the interdigital electrodes overlap to the outside, thereby further inhibiting the transverse vibration mode.

[0066] Please refer to FIG. 11 and FIG. 12, FIG. 11 is a curve diagram of admittance characteristics, wherein the abscissa is normalized frequency, the ordinate is normalized admittance, the solid line is the admittance characteristics curve of the acoustic resonator 10 provided by the embodiment of the present application as shown in FIG. 10, and the dotted line is the admittance characteristics curve of the acoustic resonator 10 of the conventional structure as shown in FIG. 1. In FIG. 11, the two admittance characteristics curves almost completely coincide, the resonance frequency Fs is about 0.76, and the anti-resonance frequency Fp is about 0.80, that is, the improved acoustic resonator 10 of the present application does not affect the admittance characteristics of the acoustic resonator 10. FIG. 12 is a curve diagram of quality factor, wherein the abscissa is normalized frequency, and the ordinate is normalized quality factor. The main working frequency range of the acoustic resonator 10 is between the resonance frequency Fs and the anti-resonance frequency Fp, and in this range, the larger the quality factor is, the better, and the more slowly the quality factor changes with frequency, the better. As can be seen from FIG. 12, in the frequency range of 0.76-0.77, the quality factor of the acoustic resonator 10 provided by the embodiment of the present application is slightly lower than that of the conventional structure, but the quality factor of the acoustic resonator 10 provided by the embodiment of the present application changes more slowly with frequency; in the frequency range of 0.77-0.80, the quality factor of the acoustic resonator 10 provided by the embodiment of the present application is higher than that of the conventional structure, and the quality factor of the acoustic resonator 10 provided by the embodiment of the present application changes more slowly with frequency, and the acoustic resonator 10 of the conventional structure has multiple mutation points (the positions indicated by the arrows in FIG. 12) in this frequency range, which correspond to the frequencies at which the acoustic resonator 10 leaks energy and the transverse mode of the acoustic wave is more serious. Thus, it can be seen that the acoustic resonator 10 provided by the embodiment of the present application has better performance than the conventional acoustic resonator 10.

[0067] In some embodiments, the periodic variation of the distance from the second end of the first plurality of interdigital electrodes 111 to the center line R in the X direction is the same as the periodic variation of the distance from the second end of the second plurality of interdigital electrodes 112 to the center line R. The periodic variation can include a period size. For example, in FIG. 10, the period size T is the length of 8 interdigital electrodes arranged in the X direction. The periodic variation can also include the variation values of the distance from the second end of the same kind of interdigital electrodes to the center line R in a period. For example, in a period of the periodic variation of the first plurality of interdigital electrodes 111, there are 4 first plurality of interdigital electrodes 111, and the distance from the second end of the first plurality of interdigital electrodes 111 to the center line R in the X direction is 1, 2, 2, 1 in turn, and the variation values are 1, 0, 1 in turn. Similarly, in a period of the periodic variation of the second plurality of interdigital electrodes 112, there are also 4 second plurality of interdigital electrodes 112, and the distance from the second end of the second plurality of interdigital electrodes 112 to the center line R in the X direction is 3, 4, 4, 3 in turn, and the variation values are 1, 0, 1 in turn. In this way, the variation of the second plurality of interdigital electrodes 112 in a period is the same as the variation of the first plurality of interdigital electrodes 111 in a period. The periodic variation can also include that the distance between the reflective electrode 210 and any two adjacent first plurality of interdigital electrodes 111 in the X direction is equal. Thus, the surface acoustic wave excited by the interdigital electrodes gradually weakens to the same extent in the Y direction from the area where the interdigital electrodes overlap.

[0068] For example, in the X direction, the aperture of the interdigital transducer 100 remains unchanged, and the aperture is the length of the overlap of two adjacent interdigital electrodes in the Y direction, as described above. It can be understood that because the first plurality of interdigital electrodes 111 and the second plurality of interdigital electrodes 112 are arranged alternately in the X direction, the two adjacent interdigital electrodes are the first plurality of interdigital electrodes 111 and the second plurality of interdigital electrodes 112, respectively. In this way, the periodic variation of the distance from the second end of the first plurality of interdigital electrodes 111 to the center line R in the X direction can be ensured to be the same as the periodic variation of the distance from the second end of the second plurality of interdigital electrodes 112 to the center line R.

[0069] In some embodiments, the plurality of reflective electrodes 210 further comprises at least one second reflective electrode 212, the second reflective electrode 212 comprising a third sub-electrode 2121 and a fourth sub-electrode 2122 spaced apart in the Y direction. It can be appreciated that the third sub-electrode 2121 and the fourth sub-electrode 2122 both extend in the Y direction, and the third sub-electrode 2121 and the fourth sub-electrode 2122 can extend along the same straight line. That is, the second reflective electrode 212 does not extend continuously, and there is an interruption. The third sub-electrode 2121 of the second reflective electrode 212 comprises a first end and a second end, and the second sub-electrode 2122 of the second reflective electrode 212 also comprises a first end and a second end, and the second end of the third sub-electrode 2121 and the second end of the fourth sub-electrode 2122 form a second gap 2123. Similarly, the first end of the third sub-electrode 2121 and the first end of the plurality of second interdigital electrodes 112 are located on the same side of the center line R, and the second end of the third sub-electrode 2121 and the second end of the plurality of second interdigital electrodes 112 vary periodically in distance from the center line R. Exemplarily, in one period, the second end of the third sub-electrode 2121 and the second end of the plurality of second interdigital electrodes 112 gradually increase and then gradually decrease in distance from the center line R. In this way, the second gap 2123 formed by the second end of the third sub-electrode 2121 can also cancel the sound waves reflected by the surface acoustic waves that do not propagate in the X direction, and thus can further cancel the surface acoustic waves generated by the second end of the plurality of second interdigital electrodes 112, and further suppress the transverse vibration mode.

[0070] Exemplarily, the first reflective electrode 211 and the second reflective electrode 212 are alternately arranged in the X direction. In this way, the first gap 2113 formed by the first reflective electrode 211 and the second gap 2123 formed by the second reflective electrode 212 can also be alternately arranged, so that the periodic variation of the second end of the first reflective electrode 211 and the second end of the second reflective electrode 212 can remain the same.

[0071] For example, one of the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 closest to the reflector 200 is the second interdigital electrode 112, and one of the plurality of reflective electrodes closest to the interdigital transducer 100 is the first reflective electrode 211 (e.g., the first reflective electrode 212 in the reflector 200 on the left in FIG. 10). In this way, the spacing condition between the first reflective electrode 212 and the first interdigital electrode 111 closest to the first reflective electrode 212 can be consistent with the spacing condition between any two adjacent first interdigital electrodes 111 in the plurality of first interdigital electrodes 111, which refers to the number of other electrodes arranged between the two adjacent first interdigital electrodes 111, or the number of other electrodes arranged between the first gap 2113 and the first interdigital electrode 111 closest to the first gap 2113, or the number of other electrodes arranged between the second gap 2123 and the second interdigital electrode 112 closest to the second gap 2123.

[0072] For example, one of the plurality of first interdigital electrodes 111 and the plurality of second interdigital electrodes 112 closest to the reflector 200 is the first interdigital electrode 111, and one of the plurality of reflective electrodes closest to the interdigital transducer 100 is the second reflective electrode 212 (e.g., the second reflective electrode 212 in the reflector 200 on the left in FIG. 10). In this way, the spacing condition between the second reflective electrode 212 and the second interdigital electrode 112 closest to the second reflective electrode 212 can be consistent with the spacing condition between any two adjacent second interdigital electrodes 112 in the plurality of second interdigital electrodes 112.

[0073] Referring to FIG. 13, in some embodiments, the plurality of reflective electrodes further includes a third reflective electrode 213, which can be arranged continuously in a direction intersecting the X direction, for example, the third reflective electrode 213 is arranged continuously in the Y direction. Continuous arrangement refers to that the third reflective electrode 213 has no gap, for example, when the reflector 200 includes a third bus electrode 223 and a fourth bus electrode 224, the third reflective electrode 213 is arranged between the third bus electrode 223 and the fourth bus electrode 224 and connects the third bus electrode 223 and the fourth bus electrode 224. In this way, the third reflective electrode 223 can increase the reflectivity of the reflector 200 in the X direction and reduce energy leakage in the X direction.

[0074] For example, the third reflective electrode 213 is farther 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 arranged between the third reflective electrode 213 and the interdigital transducer 100, so that the random reflection of surface acoustic waves in the non-X direction occurs in a region closer to the interdigital transducer 100, increasing the random reflection to suppress the transverse vibration mode, and reducing the energy leakage of the surface acoustic waves in the X direction.

[0075] In some embodiments, since the distance from the second end of the first sub-electrode 2111 to the center line R varies periodically for the plurality of first interdigital electrodes 111, the curve formed based on the second end of the first sub-electrode 2111 and the second end of the plurality of first interdigital electrodes 111 can be a periodic function graph. Exemplarily, the curve formed based on the second end of the first sub-electrode 2111 and the second end of the plurality of first interdigital electrodes 111 can be a first envelope line L1 formed according to the second end of the first sub-electrode 2111 and the second end of the plurality of first interdigital electrodes 111, which is a periodic function graph. The envelope line refers to a virtual line formed by connecting the second end of the first sub-electrode 2111 and the second end of the plurality of interdigital electrodes, and the second end of the first sub-electrode 2111 and the second end of the plurality of interdigital electrodes are both located on the same side of the virtual line and in contact with the virtual line, at this time, it can also be considered that the second end of the first sub-electrode 2111 and the second end of the plurality of interdigital electrodes are both located on the virtual line.

[0076] Similarly, since the distance from the plurality of second interdigital electrodes 112 to the center line R varies periodically, the curve formed based on the second end of the plurality of second interdigital electrodes 112 can also be a periodic function graph. Exemplarily, the curve is also a second envelope line L2 formed according to the second end of the plurality of second interdigital electrodes 112. When the reflector 200 includes the second reflective electrode 212, the second end of the third sub-electrode 2111 and the second end of the plurality of second interdigital electrodes 112 jointly form the second envelope line L2.

[0077] It can be understood that, since the first envelope line L1 formed by the second end of the plurality of first interdigital electrodes 111 is a periodic function graph, in the periodic function graph, the connecting line of the plurality of maximum points is a straight line, which is parallel to the X direction; similarly, since the second envelope line L2 formed by the second end of the plurality of second interdigital electrodes 112 is also a periodic function graph, the connecting line of the plurality of minimum points of the periodic function is also a straight line, which is also parallel to the X direction. In this case, the aforementioned center line R can also be a straight line with equal distance to the aforementioned two straight lines.

[0078] Exemplarily, the second envelope line L2 can be a broken line function graph such as shown in FIGS. 10 and 13, or a trigonometric function graph such as shown in FIGS. 14 and 15. The difference between the acoustic resonator 10 in FIGS. 14 and 15 is that the reflector 200 of the acoustic resonator 10 in FIG. 15 includes a third reflective electrode 213. When the first envelope line L1 and the second envelope line L2 are broken line function graphs, the angle between any straight line segment of the broken line function and the X direction ranges from 1° to 70°, for example, in FIG. 13, the angle between the second envelope line L2 and the X direction ranges from 1° to 70°. The angle can be 1°, 10°, 25°, 45°, 60°, 70°, etc. In this way, the effective area of the interdigital transducer 100 can be increased; at the same time, the first gap 2113 has a reflection effect on surface acoustic waves propagating in a non-X direction.

[0079] Please refer to FIG. 10 and FIG. 16. In some embodiments, the acoustic resonator 10 can include a transverse mode suppression structure. The transverse mode suppression structure can be disposed on the interdigital transducer 100. In this case, the transverse mode suppression structure can 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. The fourth transverse mode suppression structure 134 is disposed between the first end and the second end of the second interdigital electrode 112. In addition, the distance 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 varies periodically. For example, the distance 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 gradually increases and then gradually decreases. For example, in the case where the second ends of the plurality of first interdigital electrodes 111 are also used to form the first envelope line L1, that is, in the case where 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, in the case where the second ends of the plurality of second interdigital electrodes 112 are located on the second envelope line L2, that is, in the case where 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 the second reflective electrode 212, 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 mode of the surface acoustic wave can be suppressed by the transverse mode suppression structure, and energy leakage can be reduced.

[0080] For example, please refer to FIG. 16 and FIG. 17. The transverse mode suppression structure can be a piston structure such as that shown in FIG. 16, which can be formed by increasing the thickness of the interdigital electrode at the position of the transverse mode suppression structure. The transverse mode suppression structure can also be a hammerhead structure such as that shown in FIG. 17, which can be formed by increasing the size of the interdigital electrode in the X direction at the position of the transverse mode suppression structure.

[0081] Similarly, the transverse mode suppression structure can also be provided on the interdigital transducer 100 when the curve formed by the second end of the first sub-electrode 2111 and the second end of the plurality of first interdigital electrodes 111 is a periodic function of the pattern. As shown in FIG. 18, the interdigital transducer 100 includes a piston structure; as shown in FIG. 19, the interdigital transducer 100 includes a hammerhead structure.

[0082] Similarly, referring to FIGS. 20-23, the interdigital transducer 100 can also include a transverse mode suppression structure when the reflector 200 includes a third reflecting electrode 213. As shown in FIGS. 20 and 21, the interdigital transducer 100 includes a piston structure; as shown in FIGS. 22 and 23, the interdigital transducer 100 includes a hammerhead structure.

[0083] Referring to FIGS. 16 and 24, the transverse mode suppression structure can also be provided on the reflector 200, which can 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 provided on the first reflecting electrode 211. The fifth transverse mode suppression structure 235 can be provided at the second end of the first sub-electrode 2111, such that the distances of 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 of 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 in a gradually increasing and then gradually decreasing manner. The sixth transverse mode suppression structure 236 can be provided 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 of 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 change periodically in a gradually increasing and then gradually decreasing manner.

[0084] Similarly, referring to FIGS. 24 and 25, the transverse mode suppression structure can be a piston structure such as shown in FIG. 24, or a hammerhead structure such as shown in FIG. 15.

[0085] Similarly, the transverse mode suppression structure can also be provided on the interdigital transducer 100 when the curve formed by the second end of the first sub-electrode 2111 and the second end of the plurality of first interdigital electrodes 111 is a periodic function of the pattern. As shown in FIG. 26, the interdigital transducer 100 includes a piston structure; as shown in FIG. 27, the interdigital transducer 100 includes a hammerhead structure.

[0086] Similarly, please refer to FIGS. 28-31, when the reflector 200 comprises a third reflective electrode 213, the transverse mode suppression structure can also be provided on the reflector 200. Meanwhile, the transverse mode suppression structure can also be provided on the interdigital transducer 100, as shown in FIGS. 28 and 29, the interdigital transducer 100 comprises a piston structure; as shown in FIGS. 30 and 31, the interdigital transducer 100 comprises a hammerhead structure.

[0087] In addition, the embodiments of the present application also provide a filter 1, which comprises any possible acoustic resonator 10 proposed in the foregoing embodiments. 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, an active acoustic filter, or the like.

[0088] In some embodiments, please refer to FIG. 32, which is a schematic structural diagram of a filter 1, which is a ladder type filter (LTF).

[0089] The filter 1 can comprise an input terminal 2, an output terminal 3, a ground terminal 4, and a plurality of resonators 10. At least two acoustic resonators 10 of the plurality of 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 arranged between the path and the ground terminal 4, for example, one acoustic resonator 10 is arranged between the two acoustic resonators 10 connected in series and the ground terminal 4. The input terminal 2 is used for inputting a signal to be filtered, and the output terminal 3 is used for outputting a filtered signal.

[0090] In some embodiments, please refer to FIG. 33, which is a schematic structural diagram of another filter 1, which is a double mode surface acoustic wave filter (DMS). The filter 1 can comprise an input terminal 2, an output terminal 3, and an acoustic resonator 10, and the acoustic resonator 10 can comprise at least two interdigital transducers 100.

[0091] For example, the acoustic resonator 10 can comprise two interdigital transducers 100. The two interdigital transducers 100 can be divided into two interdigital transducers 100 along the extension direction of the interdigital electrodes (such as the Y direction in FIG. 11) of any interdigital transducer 100 in the foregoing embodiments. Thus, the two interdigital transducers 100 are both arranged between the two reflectors 200. It can be understood that the structures of the two interdigital transducers 100 are similar. The number of interdigital electrodes included in the two interdigital transducers 100 can be the same or different. The input terminal 2 can be connected to the bus electrode of one interdigital transducer 100, and the output terminal 3 can be connected to the bus electrode of the other interdigital transducer 100. The bus electrode connected to the input terminal 2 and the bus electrode connected to the output terminal 3 can be located on the same side or different sides of the bus electrodes. The bus electrode of the interdigital transducer 100 not connected to the input terminal 2 or the output terminal 3 can be grounded.

[0092] Exemplarily, please refer to FIG. 34, which is a structural schematic diagram of another filter 1. The filter 1 includes three interdigital transducers 100. The three interdigital transducers 100 are arranged in sequence between two reflectors 200. Similarly, the three interdigital transducers 100 can be divided into three interdigital transducers 100 from one interdigital transducer 100 in the foregoing embodiments along the extension direction of the interdigital electrode (such as the Y direction in FIG. 11). The bus electrode of the interdigital transducer 100 in the middle of the three interdigital transducers 100 can be connected with the input end 2, and the two interdigital transducers 100 on the two sides can be connected with the output end 3. The bus electrode connected with the input end 2 and the bus electrode connected with the output end 3 can be located on the same side or different sides of the interdigital electrode. The bus electrode of the interdigital transducer 100 not connected with the input end 2 or the output end 3 can be grounded.

[0093] Please refer to FIG. 35, the embodiment of the application further provides an electronic device 5, which can be, for example, a mobile phone, a pad, a personal digital assistant (PDA), a television, a smart wearable product (for example, a smart watch, a smart bracelet), a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a charging household small appliance (for example, a soybean milk machine, a sweeping robot), a drone, a radar, an aerospace device, and a vehicle-mounted device, and different types of user devices or terminal devices, and a communication device, such as a wireless network card, a wireless router, a wireless transceiver module, or a communication base station. The specific form of the electronic device is not specially limited in the embodiment of the application.

[0094] The electronic device 5 can include a system on chip (SOC) 7, a radio frequency chip 8, and the like arranged on a printed circuit board (PCB) 6. The PCB is used to carry and connect the system on chip 7, the radio frequency chip 8, and the like. The radio frequency chip 8 can include a filter 1, a processor 9, and the like. The filter 1 is an important part of radio frequency signal processing, which is used to pass signals of a specific frequency and block signals of other frequencies. The processor 9 is connected with the filter 1 and is used to process various signals, for example, signals of a specific frequency passing through the filter 1.

[0095] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical scope disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An acoustic resonator, characterized by, The piezoelectric substrate comprises: an interdigital transducer disposed on the piezoelectric substrate, comprising 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 being located between the first bus electrode and the second bus electrode and being alternately arranged along a first direction; the first interdigital electrode comprises a first end connected with the first bus electrode and a second end away from the first bus electrode, and the second interdigital electrode comprises a first end connected with the second bus electrode and a second end away from the second bus electrode; two reflectors respectively disposed on opposite sides of the interdigital transducer in the first direction, the reflectors comprising a plurality of reflection electrodes arranged along the first direction, the plurality of reflection electrodes comprising at least one first reflection electrode, the first reflection electrode comprising 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 comprises a first end and a second end, and the second sub-electrode also comprises 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 end of the plurality of first interdigital electrodes are located on the same side of a center line of the interdigital transducer, and the distance from the second end of the first sub-electrode and the second end of the plurality of first interdigital electrodes to the center line changes periodically, the center line being parallel to the first direction; the distance from the second end of the plurality of second interdigital electrodes to the center line also changes periodically. Along the first direction, the periodic change of the distance from the second end of the plurality of first interdigital electrodes to the center line is the same as the periodic change of the distance from the second end of the plurality of second interdigital electrodes to the center line.

2. The acoustic resonator of claim 1, wherein, Along the first direction, the aperture of the interdigital transducer remains unchanged; the aperture is the length of the adjacent first interdigital electrode and second interdigital electrode overlapping each other in the second direction, the second direction being perpendicular to the first direction.

3. The acoustic resonator of claim 2, wherein, The plurality of reflection electrodes further comprises at least one second reflection electrode, the second reflection electrode comprising a third sub-electrode and a fourth sub-electrode spaced apart in the second direction; 4. The acoustic resonator of any one of claims 1-3, wherein, the third sub-electrode comprises a first end and a second end, and the fourth sub-electrode also comprises 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; wherein the first end of the third sub-electrode and the first end of the plurality of second interdigital electrodes are located on the same side of a center line of the interdigital transducer, and the distance from the second end of the third sub-electrode and the second end of the plurality of second interdigital electrodes to the center line changes periodically. The first reflection electrode and the second reflection electrode are alternately arranged along the first direction.

5. The acoustic resonator of claim 4, wherein, The electrode closest to the reflector among the plurality of first interdigital electrodes and the plurality of second interdigital electrodes is a second interdigital electrode, and the electrode closest to the interdigital transducer among the plurality of reflection electrodes is a first reflection electrode; 6. An acoustic resonator as claimed in claim 4 or 5, characterised in that, or, ​ One of the plurality of first interdigital electrodes and the plurality of second interdigital electrodes closest to the reflector is a first interdigital electrode, and one of the plurality of reflective electrodes closest to the interdigital transducer is a second reflective electrode.

7. The acoustic resonator of any one of claims 4-6, wherein, The plurality of reflective electrodes further comprises a third reflective electrode, which is arranged continuously in the second direction; The third reflective electrode is farther away from the interdigital transducer than the first reflective electrode and the second reflective electrode.

8. The acoustic resonator of any one of claims 1-7, wherein, The interdigital transducer further comprises: A first transverse mode suppression structure arranged at the second end of the first interdigital electrode; A second transverse mode suppression structure arranged between the first end and the second end of the first interdigital electrode; A third transverse mode suppression structure arranged at the second end of the second interdigital electrode; A fourth transverse mode suppression structure arranged between the first end and the second end of the second interdigital electrode; The distance from the center line of the second end of the first sub-electrode, the first transverse mode suppression structure, and the fourth transverse mode suppression structure changes periodically; The distance from the center line of the second transverse mode suppression structure and the third transverse mode suppression structure changes periodically.

9. The acoustic resonator of claim 8, wherein, The reflector further comprises: A fifth transverse mode suppression structure arranged at the second end of the first sub-electrode; A sixth transverse mode suppression structure arranged on the part of the first sub-electrode away from the second sub-electrode; The distance from the center line of the fifth transverse mode suppression structure, the first transverse mode suppression structure, and the fourth transverse mode suppression structure changes periodically; The distance from the center line of the sixth transverse mode suppression structure, the second transverse mode suppression structure, and the third transverse mode suppression structure changes periodically.

10. The acoustic resonator of any one of claims 1-9, wherein, The second end of the first sub-electrode and the second end of the plurality of first interdigital electrodes are located on a first envelope line, and the second end of the plurality of second interdigital electrodes is located on a second envelope line; The first envelope line and the second envelope line are the graphs of a broken line function or a trigonometric function.

11. The acoustic resonator of claim 10, wherein, The first envelope line and the second envelope line are the graphs of a broken line function, and the angle between any straight line segment of the broken line function and the first direction ranges from 1° to 70°.

12. A filter, characterized by An acoustic resonator comprising any one of the acoustic resonators of claims 1-11.

13. A radio frequency chip, characterized by A filter comprising a processor and the filter of claim 12, wherein the processor is connected to the filter.

14. An electronic device, comprising: A radio frequency chip comprising a printed circuit board and the radio frequency chip of claim 13, wherein the radio frequency chip is arranged on the printed circuit board.

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