Surface acoustic wave resonator and filter

Abstract

The invention discloses a surface acoustic wave resonator and a filter, and relates to the technical field of communication, the surface acoustic wave resonator comprises an interdigital electrode, the interdigital electrode comprises a first bus bar and a second bus bar which are oppositely arranged, the first bus bar extends towards the second bus bar to form a plurality of first interdigital electrodes, and the second bus bar extends towards the second bus bar to form a plurality of second interdigital electrodes; a plurality of first interdigital electrodes extend out of the first bus bar, a plurality of second interdigital electrodes extend out of the second bus bar towards the first bus bar, the first interdigital electrodes and the second interdigital electrodes are alternately arranged in the first direction at intervals, and the projection overlapping area of the first interdigital electrodes and the second interdigital electrodes in the first direction is an effective area. The first interdigital electrodes are connected through the first short-circuit grid bars, and the second interdigital electrodes are connected through the second short-circuit grid bars. According to the surface acoustic wave resonator and the filter provided by the invention, the preparation difficulty of the interdigital electrode can be reduced, and the performance of the surface acoustic wave resonator can be improved.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a surface acoustic wave resonator and a filter. Background Art

[0002] Surface acoustic wave (SAW) resonators use the propagation characteristics of surface acoustic waves on the surface of piezoelectric materials to generate surface acoustic waves through excitation electrodes to achieve signal resonance and processing. Surface acoustic wave resonators are usually composed of piezoelectric materials, excitation electrodes, and load electrodes. Signal resonance is achieved by generating surface acoustic waves on the surface of piezoelectric materials. Surface acoustic wave filters are usually composed of multiple surface acoustic wave resonators. By reasonably designing the frequency and bandwidth of the resonator, signal frequency selection and filtering are achieved. They are widely used in communication systems, radar systems, radio receivers and other fields for signal processing, frequency selection and filtering.

[0003] Due to the limited aperture of wave propagation, the surface acoustic wave resonator based on the piezoelectric single crystal thin film substrate may generate transverse modes through the diffraction effect, and a large number of clutter will appear between the resonance point and the anti-resonance point, which seriously affects the flatness of the passband of the surface acoustic wave filter and worsens the insertion loss of the filter. In order to suppress the transverse mode, the prior art usually adds a special structure at the end of the finger of the forked electrode to focus the energy of the surface acoustic wave in the effective resonance area, but the special structure extends to the outside of the finger, so that the gap between the special structures on two adjacent fingers is extremely small, and the forked electrode is formed by photolithography, and the extremely small gap increases the difficulty of photolithography, and the special structure destroys the continuity of the finger, which is easy to introduce other parasitic modes, affecting the performance of the surface acoustic wave resonator. Summary of the invention

[0004] The purpose of the present application is to provide a surface acoustic wave resonator and a filter, which can reduce the difficulty of preparing interdigital electrodes and improve the performance of the surface acoustic wave resonator.

[0005] On the one hand, an embodiment of the present application provides a surface acoustic wave resonator, including interdigitated electrodes, the interdigitated electrodes including a first bus bar and a second bus bar arranged relatively to each other, the first bus bar extending a plurality of first interdigitated electrodes toward the second bus bar, the second bus bar extending a plurality of second interdigitated electrodes toward the first bus bar, the first interdigitated electrodes and the second interdigitated electrodes being alternately arranged at intervals in a first direction, the area where the first interdigitated electrodes and the second interdigitated electrodes overlap in the first direction is an effective area, outside the effective area, the plurality of first interdigitated electrodes are connected by a first short-circuit grid bar, and the plurality of second interdigitated electrodes are connected by a second short-circuit grid bar.

[0006] As an implementable manner, along the first direction, the length of the first interdigital electrode first increases and then decreases, and the length of the second interdigital electrode first increases and then decreases; or, the length of the first interdigital electrode first increases and then decreases, and the length of the second interdigital electrode first decreases and then increases.

[0007] As an implementable manner, the first short-circuit bar is in a zigzag shape, and the second short-circuit bar is in a zigzag shape.

[0008] As an implementable manner, the first short-circuit bar is in an arc shape, and the second short-circuit bar is in an arc shape.

[0009] As an implementable manner, the center angle of the first short-circuit bar is between 30-60°, and the center angle of the second short-circuit bar is between 30-60°.

[0010] As an implementable manner, the first short-circuit bars include a plurality of first short-circuit bars, which are arranged in parallel along the second direction; the second short-circuit bars include a plurality of second short-circuit bars, which are arranged in parallel along the second direction, and the first direction is perpendicular to the second direction.

[0011] As an implementable manner, along the second direction, the first short-circuit grid bar and the second short-circuit grid bar each include a plurality of fold line units or arc units, wherein each fold line unit includes two grid bars having an obtuse angle, and each arc unit has continuity.

[0012] As an implementable manner, a plurality of first pseudo fingers connected to the first bus bar are arranged between the first bus bar and the first short-circuit grid bar, and the plurality of first pseudo fingers correspond one-to-one to the second interdigitated electrodes and their projections in the second direction overlap; a plurality of second pseudo fingers connected to the second bus bar are arranged between the second bus bar and the second short-circuit grid bar, and the plurality of second pseudo fingers correspond one-to-one to the first interdigitated electrodes and their projections in the second direction overlap.

[0013] As an implementable method, a plurality of third pseudo fingers connected to the first short-circuit bar are arranged between the first short-circuit bar and the second interdigitated electrode, and the plurality of third pseudo fingers correspond one-to-one to the second interdigitated electrodes and their projections in the second direction overlap; a plurality of fourth pseudo fingers connected to the second short-circuit bar are arranged between the second short-circuit bar and the first interdigitated electrode, and the plurality of fourth pseudo fingers correspond one-to-one to the first interdigitated electrodes and their projections in the second direction overlap.

[0014] Another aspect of an embodiment of the present application provides a filter, comprising a plurality of cascaded surface acoustic wave resonators as described above.

[0015] The beneficial effects of the embodiments of the present application include: The surface acoustic wave resonator provided by the present application comprises interdigitated electrodes, wherein the interdigitated electrodes comprise a first bus bar and a second bus bar arranged opposite to each other, wherein the first bus bar extends a plurality of first interdigitated electrodes toward the second bus bar, and the second bus bar extends a plurality of second interdigitated electrodes toward the first bus bar, wherein the first interdigitated electrodes and the second interdigitated electrodes are alternately arranged in a first direction, wherein the region where the projections of the first interdigitated electrodes and the second interdigitated electrodes overlap in the first direction is an effective region, and outside the effective region, the plurality of first interdigitated electrodes are connected by a first short-circuit grid bar, wherein the plurality of first interdigitated electrodes are respectively connected to The first bus bar is connected so that the first short-circuit grid is connected to the first bus bar through a plurality of first interdigitated electrodes, that is, the potential on the first short-circuit grid and the first bus bar is equal, so that a short-circuit area is formed between the first short-circuit grid and the first bus bar, so that there is no electric field distribution between the first short-circuit grid and the first bus bar, thereby suppressing the excitation of the transverse mode; similarly, a plurality of second interdigitated electrodes are connected through the second short-circuit grid, and there is no electric field distribution between the second short-circuit grid and the second bus bar, thereby suppressing the excitation of the transverse mode and improving the performance of the surface acoustic wave resonator. In addition, since the first short-circuit grid and the second short-circuit grid only need to adjust the mask plate during etching during processing, no particularly thin grid bars are required, thereby reducing the difficulty of preparing the interdigitated electrodes. Therefore, the surface acoustic wave resonator of the present application can reduce the difficulty of preparing the interdigitated electrodes and improve the performance of the surface acoustic wave resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 One of the structural schematic diagrams of a surface acoustic wave resonator provided in an embodiment of the present application; Figure 2 A second structural schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Figure 3 A third structural schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Figure 4 A fourth structural schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Figure 5 A fifth structural diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Figure 6 A sixth structural diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Figure 7 A seventh structural diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Figure 8 An eighth structural schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Fig. 9 A ninth structural diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Fig.10 A tenth structural diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Fig.11 The eleventh structural diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Fig.12 A twelfth structural diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Fig.13 A thirteenth schematic diagram of the structure of a surface acoustic wave resonator provided in an embodiment of the present application; Fig.14 A fourteenth structural diagram of a surface acoustic wave resonator provided in an embodiment of the present application; Fig.15 A structural schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present application is shown in FIG15; Fig.16 A circuit connection diagram of a filter provided in an embodiment of the present application; Fig.17 A comparison diagram of the admittance characteristic curves of the embodiment of the present application and the comparative example; Fig.18 for Fig.17 Enlarged view of the middle circle; Fig.19 A comparison diagram of the real part of the admittance curves of the embodiment of the present application and the comparative example; Fig. 20 It is a comparison diagram of the passband characteristic curves of the embodiment of the present application and the comparative example.

[0018] Icon: 100-surface acoustic wave resonator; 110-interdigitated electrodes; 120-first bus bar; 121-first interdigitated electrodes; 122-first short-circuit bars; 123-first dummy fingers; 124-third dummy fingers; 130-second bus bar; 131-second interdigitated electrodes; 132-second short-circuit bars; 133-second dummy fingers; 134-fourth dummy fingers; 140-effective area; 151-broken line unit; 152-arc unit; 161-support layer; 162-high sound velocity layer; 163-low sound velocity layer; 164-piezoelectric layer; 171-reflection grating; 200-filter; 210-parallel resonator; 220-series resonator. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0022] The present application embodiment provides a surface acoustic wave resonator 100, such as Figure 1 and Figure 2 As shown, the interdigitated electrode 110 includes a first bus bar 120 and a second bus bar 130 arranged relatively to each other, the first bus bar 120 extends a plurality of first interdigitated electrodes 121 toward the second bus bar 130, the second bus bar 130 extends a plurality of second interdigitated electrodes 131 toward the first bus bar 120, the first interdigitated electrodes 121 and the second interdigitated electrodes 131 are alternately arranged at intervals in a first direction, and the area where the first interdigitated electrodes 121 and the second interdigitated electrodes overlap in the first direction is an effective area 140, outside the effective area 140, the plurality of first interdigitated electrodes 121 are connected by a first short-circuit grid bar 122, and the plurality of second interdigitated electrodes 131 are connected by a second short-circuit grid bar 132.

[0023] The surface acoustic wave resonator 100 provided in the embodiment of the present application is used to generate resonance of sound waves. Among them, the interdigital electrodes 110 are arranged on the piezoelectric layer 164, and the first bus bar 120 and the second bus bar 130 of the interdigital electrodes 110 are respectively connected to external signals to form a voltage difference between the first bus bar 120 and the second bus bar 130. Since the first bus bar 120 is connected to set a plurality of first interdigital electrodes 121, and the second bus bar 130 is connected to set a plurality of second interdigital electrodes 131, there is a voltage difference between the first interdigital electrodes 121 and the second interdigital electrodes 131, and the piezoelectric layer 164 vibrates under the action of the voltage difference to generate sound waves, and resonance is formed when the sound waves meet certain conditions.

[0024] In order to avoid short circuit between the first interdigitated electrode 121 and the second bus bar 130, and between the second interdigitated electrode 131 and the first bus bar 120, there is usually a certain gap between the end of the first interdigitated electrode 121 and the second bus bar 130, and similarly, there is a certain gap between the end of the second interdigitated electrode 131 and the first bus bar 120, wherein the area where the first interdigitated electrode 121 and the second interdigitated electrode 131 overlap in the first direction is the effective area 140, and an acoustic wave propagating along the first direction is formed in the effective area 140, and the gaps on both sides of the effective area 140 are outside the effective area 140.

[0025] Outside the effective area 140, a plurality of first interdigital electrodes 121 are connected through the first short-circuit bar 122, and a plurality of first interdigital electrodes 121 are connected through the first short-circuit bar 122, so that the first interdigital electrodes 121 are respectively connected to the first bus bar 120, so that the first short-circuit bar 122 and the first bus bar 120 have the same potential, that is, a short-circuit area is formed between the first short-circuit bar 122 and the first bus bar 120, so that there is no electric field distribution between the first short-circuit bar 122 and the first bus bar 120, thereby suppressing the excitation of the transverse mode. Similarly, a plurality of second interdigital electrodes 131 are connected through the second short-circuit bar 132, so that the second short-circuit bar 132 and the second bus bar 130 have the same potential, that is, a short-circuit area is formed between the second short-circuit bar 132 and the second bus bar 130, so that there is no electric field distribution between the second short-circuit bar 132 and the second bus bar 130, thereby suppressing the excitation of the transverse mode.

[0026] In addition, when preparing the interdigitated electrode 110 of the bulk acoustic wave resonator of the embodiment of the present application, when etching the first bus bar 120, the first interdigitated electrode 121, the second bus bar 130, the second interdigitated electrode 131 and other structures, a mask with a first short-circuit grid 122 and a second short-circuit grid 132 can be used to prepare the interdigitated electrode 110 of the embodiment of the present application, wherein the size of the finger bars is not reduced in order to suppress the excitation of the lateral mode, thereby reducing the difficulty of preparing the interdigitated electrode 110. Therefore, the surface acoustic wave resonator 100 of the present application can reduce the difficulty of preparing the interdigitated electrode 110 and improve the performance of the surface acoustic wave resonator 100.

[0027] The first direction is the direction in which the first interdigital electrodes 121 and the second interdigital electrodes 131 are alternately arranged. Figure 1 The effective area 140 is the area where the first interdigital electrode 121 and the second interdigital electrode 131 overlap in the first direction. Figure 1 The area enclosed by the dashed box.

[0028] In practical applications, the interdigital electrodes 110 are formed on the upper surface of the surface acoustic wave resonator 100. Specifically, Figure 3 As shown, along the hierarchical direction, the surface acoustic wave resonator 100 includes a support layer 161 and a high acoustic velocity layer 162, a low acoustic velocity layer 163, and a piezoelectric layer 164 sequentially arranged on the support layer 161. The interdigitated electrode 110 is formed on the piezoelectric layer 164. A voltage difference is formed between the two fingers of the interdigitated electrode to form an acoustic wave in the piezoelectric layer 164 that propagates along the surface where the piezoelectric layer 164 is located. The acoustic wave propagates in the effective area 140. In order to avoid leakage of the acoustic wave at the edge of the effective area 140, a reflection grating 171 is respectively arranged on both sides of the interdigitated electrode 110 along the propagation direction of the acoustic wave, as shown in FIG. Figure 1 and Figure 2 shown.

[0029] Specifically, the interdigital electrodes 110 and the reflective grid 171 are made of metals such as copper, aluminum, titanium, chromium, platinum, or alloys formed by the combination of the above metals, and a stacked structure of the above metals can also be used. The piezoelectric layer 164 is made of piezoelectric materials such as quartz, lithium tantalate, lithium niobate, etc. The low acoustic velocity layer 163 is a material with temperature compensation characteristics, such as silicon dioxide, etc.; the high acoustic velocity layer 162 and the high acoustic velocity support layer 161 can be the same material, such as sapphire; or different materials, such as the high acoustic velocity layer 162 using polysilicon and the high acoustic velocity support layer 161 using high-resistance silicon.

[0030] It can be understood that the first short-circuit bar 122 is connected to multiple first interdigitated electrodes 121 outside the effective area 140, so that the first short-circuit bar 122 is arranged on a side close to the first bus bar 120; similarly, the second short-circuit bar 132 is connected to multiple second interdigitated electrodes 131 outside the effective area 140, so that the second short-circuit bar 132 is arranged on a side close to the second bus bar 130.

[0031] In summary, the interdigitated electrodes 110 of the surface acoustic wave resonator 100 provided in the present application include a first bus bar 120 and a second bus bar 130 arranged relatively to each other, the first bus bar 120 extends a plurality of first interdigitated electrodes 121 toward the second bus bar 130, the second bus bar 130 extends a plurality of second interdigitated electrodes 131 toward the first bus bar 120, and the area where the first interdigitated electrodes 121 and the second interdigitated electrodes overlap in the first direction is the effective area 140, outside the effective area 140, the plurality of first interdigitated electrodes 121 are connected by a first short-circuit grid bar 122, wherein the plurality of first interdigitated electrodes 121 are respectively connected to the first bus bar 120, The first short-circuit bar 122 is connected to the first bus bar 120 through a plurality of first interdigitated electrodes 121, that is, the potentials on the first short-circuit bar 122 and the first bus bar 120 are equal, so that a short-circuit area is formed between the first short-circuit bar 122 and the first bus bar, so that there is no electric field distribution between the first short-circuit bar 122 and the first bus bar 120, thereby suppressing the excitation of the lateral mode; similarly, the plurality of second interdigitated electrodes 131 are connected through the second short-circuit bar 132, and there is no electric field distribution between the second short-circuit bar 132 and the second bus bar 130, thereby suppressing the excitation of the lateral mode and improving the performance of the surface acoustic wave resonator 100. In addition, since the first short-circuit grid 122 and the second short-circuit grid 132 only need to adjust the mask plate during etching during processing, no particularly fine grids are required, thereby reducing the difficulty of preparing the interdigital electrodes 110. Therefore, the surface acoustic wave resonator 100 of the present application can reduce the difficulty of preparing the interdigital electrodes 110 and improve the performance of the surface acoustic wave resonator 100.

[0032] Optional, such as Figure 1 , Figure 2 and Figure 7 As shown, along the first direction, the length of the first interdigital electrode 121 increases first and then decreases, and the length of the second interdigital electrode 131 increases first and then decreases; or, the length of the first interdigital electrode 121 increases first and then decreases, and the length of the second interdigital electrode 131 decreases first and then increases.

[0033] Among them, Figure 1 and Figure 2 As shown, along the first direction, the length of the first interdigitated electrode 121 increases first and then decreases, and the length of the second interdigitated electrode 131 increases first and then decreases, so that the first short-circuit grid 122 and the second short-circuit grid 132 extend in a direction having an angle with the first direction. In this way, the sound wave propagation channel of the surface acoustic wave resonator 100 has an angle with the first direction. At the same time, each part of the resonator has a different aperture to weaken the resonance of the lateral mode, thereby further suppressing the lateral mode of the sound wave and improving the performance of the surface acoustic wave resonator 100.

[0034] In addition, if Figure 7As shown, the length of the first interdigitated electrode 121 increases first and then decreases, and the length of the second interdigitated electrode 131 decreases first and then increases. Similarly, the sound wave propagation channel of the surface acoustic wave resonator 100 has an angle with the first direction. At the same time, each part of the resonator has a different aperture to weaken the resonance of the transverse mode, thereby further suppressing the transverse mode of the sound wave and improving the performance of the surface acoustic wave resonator 100.

[0035] In one possible implementation of the embodiment of the present application, Figure 1 As shown, the first short-circuit bar 122 is in a fold line shape, and the second short-circuit bar 132 is in a fold line shape.

[0036] The zigzag shape makes the sound wave propagation channel have a corner, so that the sound wave suppression effect on the lateral mode is better.

[0037] The specific angle of the broken line is not limited in the embodiment of the present application. For example, the angle between the two bars and the first direction may be between 0-30°, preferably between 0-20°, and more preferably between 5-10°.

[0038] Optional, such as Figure 2 As shown, the first short-circuit bar 122 is in an arc shape, and the second short-circuit bar 132 is in an arc shape.

[0039] The arc shape is easier to prepare and can improve the stability of the first short-circuit bar 122 and the second short-circuit bar 132 .

[0040] In an achievable manner of the embodiment of the present application, the center angle of the first short-circuit bar 122 is between 30° and 60°, and the center angle of the second short-circuit bar 132 is between 30° and 60°.

[0041] Preferably, the center angle of the first short-circuit bar 122 is 40-60°, and the center angle of the second short-circuit bar 132 is 40-60°. More preferably, the center angle of the first short-circuit bar 122 is 45°, and the center angle of the second short-circuit bar 132 is 45°.

[0042] Optional, such as Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the first short-circuit bars 122 include a plurality of first short-circuit bars 122 arranged in parallel along the second direction; the second short-circuit bars 132 include a plurality of second short-circuit bars 132 arranged in parallel along the second direction, and the first direction is perpendicular to the second direction.

[0043] The plurality of first short-circuit bars 122 and the plurality of second short-circuit bars 132 can strengthen the short-circuit effect, thereby improving the suppression effect on the transverse mode sound waves.

[0044] Multiple first short-circuit bars 122 are arranged in parallel along the second direction, so that the angles or central angles of the multiple first short-circuit bars 122 are the same; similarly, multiple second short-circuit bars 132 are arranged in parallel along the second direction, so that the angles or central angles of the multiple second short-circuit bars 132 are the same.

[0045] In one possible implementation of the embodiment of the present application, Figure 8 , Fig. 9 , Fig.10 and Fig.11 As shown, along the second direction, the first short-circuit grid bar 122 and the second short-circuit grid bar 132 each include a plurality of fold line units 151 or arc units 152, wherein each fold line unit 151 includes two grid bars with an obtuse angle, and each arc unit 152 has continuity.

[0046] The multiple fold line units 151 or the multiple arc units 152 can suppress the transverse mode acoustic wave multiple times, thereby further suppressing the transverse mode of the acoustic wave and improving the performance of the surface acoustic wave resonator 100 .

[0047] The above steps may be repeated for a single first shorting bar 122 and a single second shorting bar 132 , or may be repeated for a unit having a plurality of first shorting bars 122 and a second shorting bar 132 .

[0048] Optional, such as Fig.12 , Fig.13 and Fig.14 As shown, a plurality of first dummy fingers 123 connected to the first bus bar 120 are arranged between the first bus bar 120 and the first short-circuit grid bar 122, and the plurality of first dummy fingers 123 correspond one-to-one to the second interdigital electrodes and their projections in the second direction overlap; a plurality of second dummy fingers 133 connected to the second bus bar 130 are arranged between the second bus bar 130 and the second short-circuit grid bar 132, and the plurality of second dummy fingers 133 correspond one-to-one to the first interdigital electrodes 121 and their projections in the second direction overlap.

[0049] The first dummy finger 123 is connected to the first bus bar 120, so that the first dummy finger 123 has the same potential as the first bus bar 120, further strengthening the short-circuit effect of the short-circuit area formed between the first short-circuit grid 122 and the first bus, thereby further suppressing the excitation of the lateral mode and improving the performance of the surface acoustic wave resonator 100.

[0050] Similarly, the second dummy finger 133 is connected to the second bus bar 130, so that the second dummy finger 133 has the same potential as the second bus bar 130, further strengthening the short-circuit effect of the short-circuit area formed between the second short-circuit grid 132 and the second bus, thereby further suppressing the excitation of the lateral mode and improving the performance of the surface acoustic wave resonator 100.

[0051] In one possible implementation of the embodiment of the present application, Fig.15 As shown, a plurality of third dummy fingers 124 connected to the first short-circuit bar 122 are arranged between the first short-circuit bar 122 and the second interdigitated electrode 131, and the plurality of third dummy fingers 124 correspond one-to-one to the second interdigitated electrodes and their projections in the second direction overlap; a plurality of fourth dummy fingers 134 connected to the second short-circuit bar 132 are arranged between the second short-circuit bar 132 and the first interdigitated electrode 121, and the plurality of fourth dummy fingers 134 correspond one-to-one to the first interdigitated electrodes 121 and their projections in the second direction overlap.

[0052] The third dummy finger 124 is provided to expand the short-circuit area outward to the side of the first short-circuit grid 122 away from the first bus bar 120 , thereby further suppressing the excitation of the lateral mode and improving the performance of the surface acoustic wave resonator 100 by expanding the short-circuit area.

[0053] Similarly, the fourth dummy finger 134 is provided to expand the short-circuit area outward to the side of the second short-circuit grid 132 away from the second bus bar 130 , thereby further suppressing the excitation of the lateral mode and improving the performance of the SAW resonator 100 by expanding the short-circuit area.

[0054] In order to further verify the performance of the surface acoustic wave resonator 100 of the embodiment of the present application, the surface acoustic wave resonator 100 formed by the interdigital electrode 110 in the prior art is used as a comparative example, and the short-circuit grid with a broken line is used as an embodiment. The performance of the comparative example and the embodiment is tested. The test results are as follows: Fig.17 , Fig.18 , Fig.19 and Fig. 20 As shown, Fig.17 A comparison diagram of the admittance characteristic curves of the embodiment of the present application and the comparative example; Fig.18 for Fig.17 Enlarged view of the middle circle; Fig.19 It is a comparison diagram of the real part of the admittance curve of the embodiment of the present application and the comparative example; From the admittance amplitude curve, it can be seen that there are multiple transverse modes such as m1~m4 between the resonant frequency fs and the anti-resonant frequency fa in the comparative example. Fig.19 This is particularly evident in the real part of the admittance curve shown; in the embodiment, the transverse mode of the surface acoustic wave resonator 100 is effectively suppressed, and is shown as a very smooth curve in the real part of the admittance curve.

[0055] The present application also discloses a filter 200, comprising a plurality of cascaded surface acoustic wave resonators 100. Specifically, the cascaded manner of the plurality of surface acoustic wave resonators 100 is not limited in the present application. For example, Fig.16As shown, a plurality of series resonators 220 and a plurality of parallel resonators 210 are included, and the plurality of parallel resonators 210 and the plurality of series resonators 220 are cascaded to form a ladder structure.

[0056] In addition, the filter 200 composed of the surface acoustic wave resonator 100 in the prior art is used as a comparative example, and the filter 200 composed of the surface acoustic wave resonator of the embodiment of the present application is used as an embodiment, and the passband characteristics of the comparative example and the embodiment are tested. The test results are as follows: Fig. 20 As shown, ripples such as n1-n4 are caused by the lateral modes of the resonator in the comparative example. These lateral modes seriously affect the passband characteristics of the filter 200. It can be seen from the passband characteristic curve of the embodiment that the weighted short-circuited metal grid effectively suppresses the lateral mode parasitics and greatly improves the passband characteristics of the surface acoustic wave filter 200.

[0057] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A surface acoustic wave resonator, characterized in that: It includes interdigitated electrodes, which include a first bus bar and a second bus bar arranged relatively to each other, the first bus bar extends a plurality of first interdigitated electrodes toward the second bus bar, the second bus bar extends a plurality of second interdigitated electrodes toward the first bus bar, the first interdigitated electrodes and the second interdigitated electrodes are alternately arranged at intervals in a first direction, the area where the first interdigitated electrodes and the second interdigitated electrodes overlap in the first direction is an effective area, and outside the effective area, a plurality of the first interdigitated electrodes are connected by a first short-circuit bar, and a plurality of the second interdigitated electrodes are connected by a second short-circuit bar.

2. The surface acoustic wave resonator according to claim 1, characterized in that: Along the first direction, the length of the first interdigital electrode increases first and then decreases, and the length of the second interdigital electrode increases first and then decreases; or, the length of the first interdigital electrode increases first and then decreases, and the length of the second interdigital electrode decreases first and then increases.

3. The surface acoustic wave resonator according to claim 2, characterized in that: The first short-circuit bar is in a zigzag shape, and the second short-circuit bar is in a zigzag shape.

4. The surface acoustic wave resonator according to claim 2, characterized in that: The first short-circuit bar is in an arc shape, and the second short-circuit bar is in an arc shape.

5. The surface acoustic wave resonator according to claim 4, characterized in that: The center angle of the first short-circuit bar is between 30° and 60°, and the center angle of the second short-circuit bar is between 30° and 60°.

6. The surface acoustic wave resonator according to claim 3 or 4, characterized in that: The first short-circuit bars include a plurality of bars, which are arranged in parallel along a second direction; the second short-circuit bars include a plurality of bars, which are arranged in parallel along a second direction, and the first direction is perpendicular to the second direction.

7. The surface acoustic wave resonator according to claim 3 or 4, characterized in that: Along the first direction, the first short-circuit grid bar and the second short-circuit grid bar each include a plurality of fold line units or arc units, wherein each fold line unit includes two grid bars with an obtuse angle, and each arc unit has continuity.

8. The surface acoustic wave resonator according to claim 1, characterized in that: A plurality of first dummy fingers connected to the first bus bar are arranged between the first bus bar and the first short-circuit grid bar, wherein the plurality of first dummy fingers correspond to the second interdigitated electrodes one by one and their projections in the second direction overlap; A plurality of second dummy fingers connected to the second bus bar are arranged between the second bus bar and the second short-circuit grid bar. The plurality of second dummy fingers correspond to the first interdigitated electrodes one by one and their projections in the second direction overlap.

9. The surface acoustic wave resonator according to claim 1 or 8, characterized in that: A plurality of third dummy fingers connected to the first short-circuit grid bar are arranged between the first short-circuit grid bar and the second interdigital electrode, wherein the plurality of third dummy fingers correspond to the second interdigital electrode one by one and their projections in the second direction overlap; A plurality of fourth dummy fingers connected to the second shorting bar are arranged between the second shorting bar and the first interdigital electrode. The plurality of fourth dummy fingers correspond to the first interdigital electrodes one by one and their projections in the second direction overlap.

10. A filter, characterized in that: A surface acoustic wave resonator comprising a plurality of cascaded connections as claimed in any one of claims 1 to 9.

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