Transducer and surface acoustic wave filter with same

Abstract

The utility model provides a transducer and a surface acoustic wave filter with the transducer. The transducer comprises a first bus bar and a second bus bar, one end of each first electrode finger strip is connected with the first bus bar, a first virtual area is arranged between the other end of each first electrode finger strip and the second bus bar, and a first metal structure is arranged on each first electrode finger strip; one end of each second electrode finger strip is connected with the second bus bar, a second virtual area is arranged between the other end of each second electrode finger strip and the first bus bar, and each second electrode finger strip is provided with a second metal structure; the first mother strip is arranged in the first virtual area, and the first mother strip is arranged in a bent mode; the second mother strip is arranged in the second virtual area, and the second mother strip is arranged in a bent mode. Through the technical scheme provided by the invention, the problems that the size of the filter is increased and the performance of the filter is influenced in the process of improving the linearity of the filter in the prior art can be solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to filter technical field, specifically, relate to a kind of transducer and the surface acoustic wave filter with it. BACKGROUND

[0002] With the development of 5G mobile communication technology, the number of communication frequency bands also increases sharply, and the frequency interval between adjacent channels is getting smaller and smaller. In mobile communication terminals, in order to realize higher rate signal transmission, more and more filters are applied to the radio frequency front end. In order to avoid interference between adjacent frequency bands, the filter needs to have a more steep transition band, a lower temperature drift coefficient and a higher quality factor (Q value).

[0003] Surface acoustic wave (SAW) and bulk acoustic wave (BAW) filters / multiplexers are key components of terminal radio frequency (RF) front-end parts, playing a key role in filtering out unwanted signals and retaining useful signals, and are widely used in mobile communication devices. Compared with traditional surface acoustic wave filters, surface acoustic wave filters based on POI (piezoelectric-on-insulator) substrates have higher energy utilization efficiency, larger electromechanical coupling coefficient, higher quality factor and lower temperature drift coefficient. Therefore, they are gradually applied to high-end radio frequency devices and high-end terminals.

[0004] In 5G radio frequency communication, there are requirements for the quality of SAW filter signal transmission, such as insertion loss, isolation, out-of-band attenuation, and increasingly high requirements for the nonlinear index that greatly affects signal distortion, to ensure inter-band uplink carrier aggregation and high-power signal transmission.

[0005] In order to improve the linearity of surface acoustic wave filters, the commonly used methods are to increase the filter sections and external capacitors. Although this method can improve the linearity of the filter to some extent, it will also increase the size of the filter, which is not conducive to size reduction and cost reduction. In addition, increasing the content ratio of Ti in the electrode finger and changing the finger width can also achieve the purpose of improving linearity, but this will affect the performance of the filter. Utility model content

[0006] The utility model provides a kind of transducer and the surface acoustic wave filter with it, to solve the problem of increasing the size of filter and affecting the performance of filter in the process of improving the linearity of filter in prior art.

[0007] According to one aspect of the utility model, provide a kind of transducer, transducer includes: first bus bar and second bus bar, first bus bar and second bus bar are oppositely arranged;Multiple first electrode fingers, multiple first electrode fingers are spaced apart along the extension direction of first bus bar, one end of first electrode finger is connected with first bus bar, and the other end of first electrode finger has first virtual area between second bus bar, first electrode finger is provided with first metal structure;Multiple second electrode fingers, multiple second electrode fingers are spaced apart along the extension direction of second bus bar, one end of second electrode finger is connected with second bus bar, and the other end of second electrode finger has second virtual area between first bus bar, first electrode finger and second electrode finger are alternately arranged along the extension direction of first bus bar and second bus bar, second electrode finger is provided with second metal structure;First female strip, it is arranged in first virtual area, first female strip is bently arranged, and first female strip cooperates with first metal structure and second metal structure to adjust the electric field intensity and electric field distribution of first virtual area;Second female strip, it is arranged in second virtual area, second female strip is bently arranged, and second female strip cooperates with first metal structure and second metal structure to adjust the electric field intensity and electric field distribution of second virtual area.

[0008] Further, the first metal structure includes a first metal sheet and a second metal sheet, the first metal sheet is arranged close to the first bus bar, and the second metal sheet is arranged at the end of the first electrode finger;The second metal structure includes a third metal sheet and a fourth metal sheet, the third metal sheet is arranged close to the second bus bar, and the fourth metal sheet is arranged at the end of the second electrode finger;The first female strip cooperates with the second metal sheet and the third metal sheet to adjust the electric field intensity and electric field distribution of the first virtual area, and the second female strip cooperates with the first metal sheet and the fourth metal sheet to adjust the electric field intensity and electric field distribution of the second virtual area.

[0009] Further, the protrusion of the first female strip is arranged close to the second bus bar, and the third metal sheet is located on the side of the first female strip close to the first bus bar;The protrusion of the second female strip is arranged close to the first bus bar, and the first metal sheet is located on the side of the second female strip close to the second bus bar.

[0010] Further, the curvature of the first female strip and the second female strip is arranged between 0 and 0.35.

[0011] Further, the distance between the end of the first electrode finger and the second bus bar is arranged between 0.1 and 1 acoustic wavelength distance;The distance between the end of the second electrode finger and the first bus bar is arranged between 0.1 and 1 acoustic wavelength distance.

[0012] Further, the width of the first metal sheet and the second metal sheet is greater than the width of the first electrode finger strip, and the single-side difference between the width of the first metal sheet and the second metal sheet and the width of the first electrode finger strip is set to be between 0.1 μm and 0.25 μm; the width of the third metal sheet and the fourth metal sheet is greater than the width of the second electrode finger strip, and the single-side difference between the width of the third metal sheet and the fourth metal sheet and the width of the second electrode finger strip is set to be between 0.1 μm and 0.25 μm.

[0013] Further, the transducer comprises a plurality of first mother strips and a plurality of second mother strips, the plurality of first mother strips are sequentially connected along the extension direction of the first bus bar, and the plurality of second mother strips are sequentially connected along the extension direction of the second bus bar.

[0014] Further, the first mother strip and the second mother strip are made of titanium-aluminum-copper alloy material, and the first metal sheet, the second metal sheet, the third metal sheet and the fourth metal sheet are made of aluminum-copper alloy material.

[0015] According to another aspect of the present application, a surface acoustic wave filter is provided, which comprises the transducer provided above, and the transducer is provided with a reflection grid at both ends.

[0016] Further, the reflection grid comprises a body; a third metal structure arranged on the body; a third mother strip and a fourth mother strip, the third mother strip and the fourth mother strip are both arranged on the body, the third mother strip and the fourth mother strip are respectively located on both sides of the third metal structure, the third mother strip and the fourth mother strip are bent, the third mother strip cooperates with the third metal structure to adjust the electric field intensity and the electric field distribution between the third mother strip and the third metal structure, and the fourth mother strip cooperates with the third metal structure to adjust the electric field intensity and the electric field distribution between the fourth mother strip and the third metal structure.

[0017] The technical scheme of the utility model is shown as follows: when an input electric signal is applied to the transducer through the first bus bar or the second bus bar, the electric signal causes an electric field to be generated in the area between the first electrode finger strip connected with the first bus bar and the second electrode finger strip connected with the second bus bar. Since the transducer is located on the piezoelectric material, the electric field can induce a piezoelectric effect, that is, mechanical vibration is generated on the surface of the material, thereby generating a surface acoustic wave. The bending characteristics of the first mother strip and the second mother strip cooperate with the first metal structure and the second metal structure to adjust the electric field intensity and the electric field distribution of the first virtual area and the second virtual area respectively, effectively reducing the coupling effect between the electrostatic field of the electrode finger strip end and the transverse wave mode strain field under the premise of not affecting the function of the transverse mode suppression structure, thereby achieving the purpose of effectively reducing the nonlinearity of the surface acoustic wave filter. Moreover, by using the above structure, only the first mother strip and the second mother strip need to be added on the transducer, without the need to increase the filter sections, so that the area of the filter can be additionally increased, thereby facilitating the assembly of the surface acoustic wave filter, and meanwhile, without the need to change the content ratio of Ti in the electrode finger strip and the finger width of the electrode finger strip, the performance of the filter can be avoided from being affected, and the normal use of the filter is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the present application, and together with the description of the exemplary embodiments of the present application, serve to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 A structure schematic view of the transducer provided by the embodiment one of the utility model is shown;

[0020] Figure 2 A structure schematic view of the surface acoustic wave filter provided by the embodiment three of the utility model is shown;

[0021] Figure 3 A sectional view of a single period of the surface acoustic wave filter based on the POI substrate provided by the embodiment three of the utility model is shown;

[0022] Figure 4 A duplexer topological structure provided by the embodiment three of the utility model is shown;

[0023] Figure 5 A comparison chart of the second harmonic varying with input power when the curvature value of the mother strip bending is different is shown;

[0024] Figure 6 A comparison chart of the third harmonic varying with input power when the curvature value of the mother strip bending is different is shown;

[0025] Figure 7The utility model discloses a structure schematic diagram of transducer provided by the second embodiment.

[0026] Among them, the above-mentioned drawing includes following sign:

[0027] 10, first bus bar;

[0028] 20, second bus bar;

[0029] 31, first electrode finger strip, 32, first virtual area, 33, first metal sheet, 34, second metal sheet;

[0030] 41, second electrode finger strip, 42, second virtual area, 43, third metal sheet, 44, fourth metal sheet;

[0031] 50, first female strip;

[0032] 60, second female strip;

[0033] 100, body;

[0034] 200, fifth metal sheet;

[0035] 300, sixth metal sheet;

[0036] 400, third female strip;

[0037] 500, fourth female strip;

[0038] 1, electrode, 2, piezoelectric layer, 3, SiO2 layer, 4, high resistance silicon layer. DETAILED DESCRIPTION

[0039] The technical scheme in the embodiments of the utility model will be described clearly and completely below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the utility model and its application or use. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the scope of protection of the utility model.

[0040] As Figure 1 And Figure 2The utility model discloses an embodiment one provides a transducer, transducer includes first bus bar 10, second bus bar 20, a plurality of first electrode finger strip 31, a plurality of second electrode finger strip 41, first female strip 50 and second female strip 60. First bus bar 10 and second bus bar 20 are oppositely arranged. A plurality of first electrode finger strip 31 are spaced apart along the extension direction of first bus bar 10, one end of first electrode finger strip 31 is connected with first bus bar 10, and the other end of first electrode finger strip 31 has first virtual area 32 with second bus bar 20, and first electrode finger strip 31 is provided with first metal structure. A plurality of second electrode finger strip 41 are spaced apart along the extension direction of second bus bar 20, one end of second electrode finger strip 41 is connected with second bus bar 20, and the other end of second electrode finger strip 41 has second virtual area 42 with first bus bar 10, and first electrode finger strip 31 and second electrode finger strip 41 are alternately arranged along the extension direction of first bus bar 10 and second bus bar 20, and second electrode finger strip 41 is provided with second metal structure. First female strip 50 is arranged in first virtual area 32, and first female strip 50 is bently arranged, and first female strip 50 cooperates with first metal structure and second metal structure to adjust the electric field intensity and electric field distribution of first virtual area 32. Second female strip 60 is arranged in second virtual area 42, and second female strip 60 is bently arranged, and second female strip 60 cooperates with first metal structure and second metal structure to adjust the electric field intensity and electric field distribution of second virtual area 42. Wherein, in the application, the transducer is an interdigital transducer.

[0041] When the input electric signal is applied to the transducer through first bus bar 10 or second bus bar 20, the electric signal makes the area between first electrode finger strip 31 connected with first bus bar 10 and second electrode finger strip 41 connected with second bus bar 20 produce an electric field. Since the transducer is located on the piezoelectric material, the electric field will induce the piezoelectric effect, that is, mechanical vibration is generated on the surface of the material, thereby generating the surface acoustic wave. The bending characteristics of first female strip 50 and second female strip 60 cooperate with first metal structure and second metal structure to adjust the electric field intensity and electric field distribution of first virtual area 32 and second virtual area 42 respectively, effectively reducing the coupling effect between the electrostatic field of the electrode finger strip end and the transverse wave mode strain field without affecting the function of the transverse mode suppression structure, thereby achieving the purpose of effectively reducing the nonlinearity of the surface acoustic wave filter. Moreover, by using the above structure, only first female strip 50 and second female strip 60 need to be added to the transducer, without the need to increase the filter section, so that the area of the filter can be increased without additional, thereby facilitating the assembly of the surface acoustic wave filter, and at the same time, without changing the content ratio of Ti in the electrode finger strip and the finger width of the electrode finger strip, the performance of the filter can be avoided, and the normal use of the filter is ensured.

[0042] As Figure 2As shown, the first metal structure includes a first metal piece 33 and a second metal piece 34, the first metal piece 33 is arranged close to the first bus bar 10, and the second metal piece 34 is arranged at the end of the first electrode finger 31. The second metal structure includes a third metal piece 43 and a fourth metal piece 44, the third metal piece 43 is arranged close to the second bus bar 20, and the fourth metal piece 44 is arranged at the end of the second electrode finger 41. The first bus bar 50 cooperates with the second metal piece 34 and the third metal piece 43 to adjust the electric field intensity and distribution of the first virtual area 32, and the second bus bar 60 cooperates with the first metal piece 33 and the fourth metal piece 44 to adjust the electric field intensity and distribution of the second virtual area 42.

[0043] With the above structure, the cooperation of the first bus bar 50 with the second metal piece 34 and the third metal piece 43 and the cooperation of the second bus bar 60 with the first metal piece 33 and the fourth metal piece 44 can more accurately control the electric field intensity, reduce the coupling between the electrostatic field and the transverse mode strain field of the surface acoustic wave, thereby effectively reducing the nonlinear effect and improving the linearity of the filter. At the same time, it is convenient to process the first metal structure and the second metal structure, and the operation is more convenient.

[0044] The protrusions of the first bus bar 50 are arranged close to the second bus bar 20, and the third metal piece 43 is located on the side of the first bus bar 50 close to the first bus bar 10. The protrusions of the second bus bar 60 are arranged close to the first bus bar 10, and the first metal piece 33 is located on the side of the second bus bar 60 close to the second bus bar 20. In this way, the bending forms of the first bus bar 50 and the second bus bar 60 can optimize the electric field intensity and distribution of the first virtual area 32 and the second virtual area 42, respectively. Moreover, the cooperation of the protrusions of the first bus bar 50 and the second bus bar 60 with the metal pieces can enhance the reflection efficiency of the surface acoustic wave inside the filter.

[0045] Moreover, the method can not only be widely used in the structure of the piezoelectric single crystal thin film structure on the insulator, but also be applicable to other TCSAW structures with thick film cover layers.

[0046] Research shows that there are three mechanisms that can cause the nonlinearity of the surface acoustic wave filter: self-mixing of the electrostatic field; mixing of the electrostatic field and the main mode strain field of the surface acoustic wave; and mixing of the electrostatic field and the transverse mode strain field of the surface acoustic wave. The self-mixing of the electrostatic field and the capacitance between the electrode fingers of the interdigital transducer are related; the mixing of the electrostatic field and the main mode strain field of the surface acoustic wave is related to the characteristics of the substrate material, such as the nonlinear dielectric constant and the electrostriction constant of the piezoelectric substrate; and the mixing of the electrostatic field and the transverse mode of the surface acoustic wave is related to the transverse mode suppression structure. In addition, the crystal asymmetry of the LT substrate surface and the gap between the interdigital transducer finger and the dummy electrode can also affect the nonlinearity of the surface acoustic wave.

[0047] Through simulation analysis, the transverse mode has a similar mode propagation mode as the main mode, and simultaneously propagates in the length direction of the finger and forms a standing wave. Multiple transverse modes are formed in the entire passband frequency band. The coupling between the electrostatic field of the electrode finger and the surface acoustic wave transverse mode strain field will affect the nonlinearity of the filter. The stronger the electrostatic field, the higher the coupling degree, and the stronger the nonlinearity.

[0048] In the present application, the end of the first electrode finger 31 is the end of the first electrode finger 31 away from the first bus bar 10, and the end of the second electrode finger 41 is the end of the second electrode finger 41 away from the second bus bar 20.

[0049] In the present application, the maximum distance X1 between the end of the electrode finger and the corresponding mother bar can be changed. The smaller X1 is, the stronger the electrostatic field between the end of the electrode finger and the corresponding mother bar, and the stronger the coupling between the transverse wave mode, the stronger the nonlinearity, and vice versa. Moreover, the distance X1 not only affects the nonlinearity of the filter, but also affects the suppression of the transverse wave mode of the filter. Therefore, by setting in this way, the bending characteristics of the first mother bar 50 and the second mother bar 60 can adjust the electric field intensity and electric field distribution of the first virtual area 32 and the second virtual area 42, respectively, effectively reducing the coupling effect between the electrostatic field of the electrode finger end and the transverse wave mode strain field without affecting the function of the transverse mode suppression structure.

[0050] In the present application, the curvature Re of the bending of the first mother bar 50 and the second mother bar 60 is set to be between 0 and 0.35. If the curvature of the bending of the first mother bar 50 and the second mother bar 60 is too large, it will also cause the generation of nonlinearity. Therefore, within the curvature range of 0 to 0.35, the electrostatic field intensity and distribution between the first electrode finger 31 and the first mother bar 50 and between the second electrode finger 41 and the second mother bar 60 can be optimized to reduce the coupling between the electric field and the transverse wave mode strain field of the surface acoustic wave, thereby effectively reducing the generation of second harmonic and third harmonic and improving the nonlinear performance of the surface acoustic wave filter.

[0051] In the processing process, the curvature Re can be tested and a suitable value can be selected, and then the first mother bar 50 and the second mother bar 60 can be processed.

[0052] In the present application, it is found through experiments that the size of Re of the filter is best between 0.1 and 0.2 in the filter design process in the frequency band of 500MHz-1GHz.

[0053] Alternatively, the curvature Re can be 0.1, 0.15, 0.2 or 0.35. In the present application, the curvature Re of the bending of the first mother bar 50 and the second mother bar 60 is 0.15.

[0054] As Figure 1As shown, the curvature of the bend Re is defined as: Re=X3 / λ, where X3 is the range of the bend of the mother strip, X4 is the distance from the end of the second electrode finger strip 41 to the first bus bar 10, and λ is the acoustic wavelength.

[0055] Further, the distance between the end of the first electrode finger strip 31 and the second bus bar 20 is set to be between 0.1 and 1 acoustic wavelength. The distance between the end of the second electrode finger strip 41 and the first bus bar 10 is set to be between 0.1 and 1 acoustic wavelength. By adjusting the distance between the end of the electrode finger strip and the corresponding bus bar within the specified range of acoustic wavelength, the electric field distribution near the end of the electrode finger strip can be optimized, the coupling strength between the electrostatic field and the strain field of the acoustic transverse mode can be reduced, and thus the nonlinear effect can be reduced. This helps to improve the linearity of the filter, especially in high-power signal and high-frequency applications, which can significantly improve the suppression of second and third harmonics.

[0056] Moreover, keeping the distance between the end of the electrode finger strip and the corresponding bus bar within a certain range helps to optimize the performance of the transverse wave mode suppression structure, ensuring the high selectivity and transverse wave suppression capability of the surface acoustic wave filter, thereby improving the filtering effect.

[0057] wherein the acoustic wavelength is different for different filters.

[0058] Optionally, to improve the nonlinearity of the surface acoustic wave filter, the thickness of the first metal sheet 33 and the second metal sheet 34 can be increased, or the width of the first metal sheet 33 and the second metal sheet 34 can be increased. In the present embodiment, the required thickness of the first metal sheet 33 and the second metal sheet 34 can be obtained by multiple tests.

[0059] Further, the transducer comprises a plurality of first mother strips 50 and a plurality of second mother strips 60, the plurality of first mother strips 50 are connected in sequence along the extension direction of the first bus bar 10, and the plurality of second mother strips 60 are connected in sequence along the extension direction of the second bus bar 20.

[0060] In this way, the plurality of sequentially connected bend mother strips can further optimize the electric field distribution. By finely adjusting the curvature and position of each mother strip, the electric field intensity and distribution can be controlled in a wider area, thereby more effectively reducing the coupling between the electrostatic field and the strain field of the acoustic transverse mode of the surface acoustic wave, reducing the generation of second and third harmonics, and improving the nonlinear performance of the surface acoustic wave filter.

[0061] Moreover, the arrangement of multiple mother strips can enhance the suppression of the acoustic transverse mode of the surface acoustic wave, and improve the selectivity of the filter. By adjusting the number and layout of the mother strips, the propagation of the transverse wave can be more effectively controlled, and the interference of the out-of-band signal with the passband signal can be reduced, thereby improving the frequency selectivity of the filter.

[0062] The first and second mother strips 50 and 60 are processed by a photolithography process. Photolithography technology can achieve micron or even nanometer level precision, ensuring that the bending curvature of the first and second mother strips 50 and 60 is accurately controlled between 0 and 0.35, thereby ensuring optimization of the electric field distribution and the performance of the surface acoustic wave filter. Moreover, the photolithography process has high standardization and automation, which can ensure that the first and second mother strips 50 and 60 of each transducer have the same design and performance in mass production, ensuring the performance consistency of the transducer and improving the processing quality of the transducer.

[0063] Further, the first and second mother strips 50 and 60 are made of titanium-aluminum-copper alloy material. Titanium-aluminum-copper alloy is a material with high mechanical strength and good corrosion resistance. Using this alloy material as the mother strip in the surface acoustic wave filter can significantly enhance the mechanical stability of the transducer, reduce damage caused by mechanical stress during processing, assembly and long-term use, and improve the durability and reliability of the surface acoustic wave filter. Moreover, titanium-aluminum-copper alloy has good electrical conductivity, which helps to reduce the resistance of the mother strip and reduce energy loss during signal transmission.

[0064] Specifically, the first, second, third and fourth metal sheets 33, 34, 43 and 44 are made of aluminum-copper alloy material. Aluminum-copper alloy combines the high electrical conductivity of aluminum and the high strength characteristics of copper, and compared to a single material, it can provide higher electrical conductivity, which means that the resistance loss caused by the metal sheet during signal transmission will be smaller, thereby improving the efficiency and signal transmission quality of the surface acoustic wave filter.

[0065] As shown in Figure 7 Embodiment two of the present application provides a transducer, which is different from embodiment one in that the width of the first and second metal sheets 33 and 34 is greater than the width of the first electrode finger strip 31, and the single-sided difference between the width of the first and second metal sheets 33 and 34 and the width of the first electrode finger strip 31 is set to be between 0.1 μm and 0.25 μm. The width of the third and fourth metal sheets 43 and 44 is greater than the width of the second electrode finger strip 41, and the single-sided difference between the width of the third and fourth metal sheets 43 and 44 and the width of the second electrode finger strip 41 is set to be between 0.1 μm and 0.25 μm.

[0066] In the present application, the first and fourth metal sheets 33 and 44 are correspondingly arranged with the second mother strip 60, and the second and third metal sheets 34 and 43 are correspondingly arranged with the first mother strip 50.

[0067] When the unilateral difference is less than 0.1 μm or greater than 0.25 μm, the cooperation of the metal sheet and the corresponding mother strip will have a negative effect on the electric field intensity and the electric field distribution, and cannot reduce the nonlinearity of the surface acoustic wave filter. However, when the unilateral difference is set to be between 0.1 μm and 0.25 μm, the widening of the metal sheet can have a positive effect on the electric field distribution, especially in the cooperation of the metal sheet and the corresponding mother strip, which can reduce the coupling effect between the electrostatic field and the acoustic transverse wave mode strain field, thereby reducing the nonlinearity of the surface acoustic wave filter and improving the signal transmission quality.

[0068] As shown in Figure 2 Embodiment three of the present application provides a surface acoustic wave filter, which comprises the transducer provided above, and the transducer is provided with a reflection grid at both ends. In this way, by using the transducer above, the coupling effect between the electrostatic field and the transverse wave mode strain field at the end of the electrode finger strip can be effectively reduced without increasing the area of the filter and changing the performance of the filter, thereby effectively reducing the nonlinearity of the surface acoustic wave filter. The setting of the reflection grid can effectively reflect the surface acoustic wave and reduce the leakage of the signal at both ends of the filter, thereby optimizing the standing wave ratio of the signal and improving the signal transmission efficiency.

[0069] Specifically, the reflection grid comprises a body 100, a third metal structure, a third mother strip 400 and a fourth mother strip 500. The third metal structure is arranged on the body 100. The third mother strip 400 and the fourth mother strip 500 are arranged on the body 100, and the third mother strip 400 and the fourth mother strip 500 are respectively located on both sides of the third metal structure. The third mother strip 400 and the fourth mother strip 500 are curvedly arranged, and the third mother strip 400 cooperates with the third metal structure to adjust the electric field intensity and the electric field distribution between the third mother strip 400 and the third metal structure. The fourth mother strip 500 cooperates with the third metal structure to adjust the electric field intensity and the electric field distribution between the fourth mother strip 500 and the third metal structure. In this way, the curved arrangement of the third mother strip and the fourth mother strip and the cooperation with the third metal structure can optimize the electric field distribution in the reflection grid area.

[0070] Specifically, the third metal structure comprises a plurality of fifth metal sheets 200 and a plurality of sixth metal sheets 300. The plurality of fifth metal sheets 200 are located on one side of the body 100, and the plurality of sixth metal sheets 300 are located on the other side of the body 100. The third mother strip 400 is located on the side of the fifth metal sheet 200 away from the sixth metal sheet 300, and the fourth mother strip 500 is located on the side of the sixth metal sheet 300 away from the fifth metal sheet 200. The groove of the third mother strip 400 and the groove of the fourth mother strip 500 are arranged close to each other.

[0071] In this way, the grooves of the third bus bar 400 and the fourth bus bar 500 are arranged close to each other, the third bus bar 400 is matched with the plurality of fifth metal sheets 200, and the fourth bus bar 500 is matched with the plurality of sixth metal sheets 300, which can optimize the electric field distribution, reduce the coupling effect of the electrostatic field and the surface acoustic wave transverse wave mode strain field, thereby effectively reducing the generation of the second harmonic and the third harmonic, and improving the linearity of the surface acoustic wave filter. This is particularly important for high-power signal transmission and carrier aggregation technology in 5G communication.

[0072] As shown in Figure 3 , the electrode 1 includes a first bus bar 10, a second bus bar 20, a first electrode finger 31, a second electrode finger 41, a first bus bar 50, and a second bus bar 60. One end of the electrode 1 is provided with a piezoelectric layer 2, the piezoelectric layer 2 away from one end of the electrode 1 is provided with a SiO2 layer 3, and the SiO2 layer 3 away from one end of the piezoelectric layer 2 is provided with a high-resistance silicon layer 4.

[0073] As shown in Figure 4 , in order to better understand the technical solutions of the present application, the band28F duplexer design in the topological structure is taken as an example, Figure 5 and Figure 6 are the changes of the second harmonic and the third harmonic with the input power measured under the condition that the port standing wave ratio VSWR is 6:1, wherein #1 is the harmonic change when Re=0, #2 is the harmonic change when Re=0.15, #1L, #1M, and #1H are the harmonics measured at the low, medium, and high three frequency points 703MHz, 725.5MHz, and 748MHz of the filter passband. As can be seen from the figure, the power of #2 is similar to that of #1, and the harmonic at the high frequency point of the passband is the worst. When the input power is 30dBm, the harmonic at the high frequency point of the passband of #2 is 4dBm better than that of #1.

[0074] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should be understood that, when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components, and / or combinations thereof.

[0075] The foregoing description, for purposes of explanation, sets forth specific values and arrangements of components and steps that are subject to many variations in the light of specific circumstances and / or material or workpiece shapes. Such examples, while indicating preferred embodiments, are not intended to limit or restrict the various concepts taught herein. It will be appreciated that the dimensions of the parts shown in the drawings are not necessarily to scale, and have been shown as such for illustrative purposes only. Techniques, methods, and apparatus known to those of ordinary skill in the art can not be discussed in detail, but are contemplated as being part of the specification, where appropriate. In all examples shown and discussed herein, any specific values are to be interpreted as merely illustrative of the examples, and not as a limitation thereon. Thus, other examples of the exemplary embodiments can have different values. It is noted that like numbers and letters on the figures identify like parts throughout the disclosure, and thus, once an item is defined in one figure, it is not necessary to discuss it further in connection with other figures where it is shown and / or discussed.

[0076] In the description of the present application, it is necessary to understand that the orientation words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship is usually based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, without making the opposite statement, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, therefore, it cannot be understood as a limitation on the scope of protection of the present application; The orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0077] For the convenience of description, spatial relative terms such as "above", "upper", "on", "top", "bottom", etc. can be used herein to describe the spatial relationship of one device or feature to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "on" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0078] In addition, it should be noted that the use of the words "first", "second" and the like to describe various components is merely intended to facilitate the differentiation of the corresponding components, and the above words have no special meaning unless otherwise stated, therefore, it cannot be understood as a limitation on the scope of protection of the present application.

[0079] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. 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 transducer, characterized in that, The transducer includes: A first busbar (10) and a second busbar (20) are arranged opposite to each other; Multiple first electrode fingers (31) are spaced apart along the extension direction of the first busbar (10). One end of each first electrode finger (31) is connected to the first busbar (10), and the other end of each first electrode finger (31) has a first virtual area (32) between it and the second busbar (20). A first metal structure is provided on each first electrode finger (31). Multiple second electrode fingers (41) are spaced apart along the extension direction of the second busbar (20). One end of each second electrode finger (41) is connected to the second busbar (20), and the other end of each second electrode finger (41) has a second virtual area (42) between it and the first busbar (10). The first electrode fingers (31) and the second electrode fingers (41) are alternately arranged along the extension directions of the first busbar (10) and the second busbar (20). A second metal structure is provided on each second electrode finger (41). The first mother strip (50) is disposed in the first virtual area (32). The first mother strip (50) is bent and cooperates with the first metal structure and the second metal structure to adjust the electric field strength and electric field distribution of the first virtual area (32). The second mother strip (60) is disposed within the second virtual area (42). The second mother strip (60) is bent and cooperates with the first metal structure and the second metal structure to adjust the electric field strength and electric field distribution of the second virtual area (42).

2. The transducer according to claim 1, characterized in that, The first metal structure includes a first metal sheet (33) and a second metal sheet (34), the first metal sheet (33) being disposed close to the first busbar (10), and the second metal sheet (34) being disposed at the end of the first electrode finger (31); The second metal structure includes a third metal sheet (43) and a fourth metal sheet (44), wherein the third metal sheet (43) is disposed near the second busbar (20) and the fourth metal sheet (44) is disposed at the end of the second electrode finger (41); The first mother strip (50) cooperates with the second metal sheet (34) and the third metal sheet (43) to adjust the electric field strength and electric field distribution of the first virtual region (32), and the second mother strip (60) cooperates with the first metal sheet (33) and the fourth metal sheet (44) to adjust the electric field strength and electric field distribution of the second virtual region (42).

3. The transducer according to claim 2, characterized in that, The protrusion of the first mother bar (50) is located close to the second bus bar (20), and the third metal sheet (43) is located on the side of the first mother bar (50) close to the first bus bar (10); The protrusion of the second mother bar (60) is located close to the first busbar (10), and the first metal sheet (33) is located on the side of the second mother bar (60) close to the second busbar (20).

4. The transducer according to claim 1, characterized in that, The curvature of the first mother bar (50) and the second mother bar (60) is set between 0 and 0.

35.

5. The transducer according to claim 1, characterized in that, The distance between the end of the first electrode bar (31) and the second bus bar (20) is set between 0.1 and 1 acoustic wavelength. The distance between the end of the second electrode bar (41) and the first bus bar (10) is set between 0.1 and 1 acoustic wavelength.

6. The transducer according to claim 2, characterized in that, The widths of the first metal sheet (33) and the second metal sheet (34) are greater than the width of the first electrode finger (31), and the difference between the widths of the first metal sheet (33) and the second metal sheet (34) and the width of the first electrode finger (31) is set between 0.1 μm and 0.25 μm. The widths of the third metal sheet (43) and the fourth metal sheet (44) are greater than the width of the second electrode finger (41), and the difference between the widths of the third metal sheet (43) and the fourth metal sheet (44) and the width of the second electrode finger (41) is set between 0.1 μm and 0.25 μm.

7. The transducer according to claim 1, characterized in that, The transducer includes a plurality of first mother bars (50) and a plurality of second mother bars (60), the plurality of first mother bars (50) being connected sequentially along the extension direction of the first busbar (10), and the plurality of second mother bars (60) being connected sequentially along the extension direction of the second busbar (20).

8. The transducer according to claim 2, characterized in that, The first mother strip (50) and the second mother strip (60) are made of titanium-aluminum-copper alloy; the first metal sheet (33), the second metal sheet (34), the third metal sheet (43) and the fourth metal sheet (44) are made of aluminum-copper alloy.

9. A surface acoustic wave filter, characterized in that, The surface acoustic wave filter includes the transducer according to any one of claims 1 to 8, and the transducer is provided with reflective gratings at both ends.

10. The surface acoustic wave filter according to claim 9, characterized in that, The reflective grating includes: Ontology(100); A third metal structure is disposed on the body (100); The third mother strip (400) and the fourth mother strip (500) are both disposed on the body (100). The third mother strip (400) and the fourth mother strip (500) are respectively located on both sides of the third metal structure. The third mother strip (400) and the fourth mother strip (500) are bent. The third mother strip (400) cooperates with the third metal structure to adjust the electric field strength and electric field distribution between the third mother strip (400) and the third metal structure. The fourth mother strip (500) cooperates with the third metal structure to adjust the electric field strength and electric field distribution between the fourth mother strip (500) and the third metal structure.

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