A surface acoustic wave resonator and filter

Abstract

The application discloses a surface acoustic wave resonator and filter. The surface acoustic wave resonator comprises a transducer; the transducer comprises a first bus bar, a second bus bar, a first electrode finger, a first dummy electrode finger, a second electrode finger and a second dummy electrode finger; the first electrode finger and the first dummy electrode finger are arranged alternately and connected to the first bus bar; the second electrode finger and the second dummy electrode finger are arranged alternately and connected to the second bus bar; the first electrode finger and the second dummy electrode finger are oppositely arranged, and a first gap is formed between the first electrode finger and the second dummy electrode finger; the second electrode finger and the first dummy electrode finger are oppositely arranged, and a second gap is formed between the second electrode finger and the first dummy electrode finger; the material density of the first dummy electrode finger and the second dummy electrode finger is a first density, the material density of the first electrode finger and the second electrode finger is a second density, and the first density is greater than the second density. The technical scheme of the application realizes suppression of transverse mode corrugation and reduction of energy loss.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a surface acoustic wave resonator and filter. Background Technology

[0002] With the development of communication technology, product terminals have put forward strict requirements on the performance of various devices. Filters are key components of communication systems, and surface acoustic wave (SAW) filters play an increasingly important role in communication systems.

[0003] Surface acoustic wave (SAW) filters are widely used in radio frequency (RF) front-ends and have advantages such as low insertion loss, wide bandwidth, and small size. However, SAW resonators have various clutter modes that seriously affect the performance of filters, and transverse mode ripple is one of the main clutter modes.

[0004] Currently, aperture weighting is mainly used to suppress transverse mode ripples. However, aperture weighting requires increasing the size of the resonator, which leads to a larger resonator volume and greater energy loss. Summary of the Invention

[0005] This invention provides a surface acoustic wave resonator and filter to suppress transverse mode ripple and reduce energy loss without changing the resonator volume.

[0006] According to one aspect of the present invention, a surface acoustic wave resonator is provided, the surface acoustic wave resonator including a transducer;

[0007] The transducer includes a first busbar, a second busbar, a plurality of first electrode fingers, a plurality of first dummy electrode fingers, a plurality of second electrode fingers, and a plurality of second dummy electrode fingers;

[0008] The first electrode finger and the first dummy electrode finger are arranged alternately and connected to the first busbar;

[0009] The second electrode finger and the second dummy electrode finger are arranged alternately and connected to the second busbar;

[0010] The first electrode finger and the second dummy electrode finger are arranged opposite to each other, and there is a first gap between the first electrode finger and the second dummy electrode finger. The second electrode finger and the first dummy electrode finger are arranged opposite to each other, and there is a second gap between the second electrode finger and the first dummy electrode finger.

[0011] The material density of the first dummy electrode finger and the second dummy electrode finger is a first density, and the material density of the first electrode finger and the second electrode finger is a second density, wherein the first density is greater than the second density.

[0012] Optionally, the width of the first dummy electrode finger and the second dummy electrode finger is a first width, and the width of the first electrode finger and the second electrode finger is a second width; the first width is greater than or equal to the second width.

[0013] Optionally, the first electrode finger includes a first end, a first electrode body, and a second end; the second electrode finger includes a third end, a second electrode body, and a fourth end; the first end is the end of the first electrode finger opposite to the second dummy electrode finger; the third end is the end of the second electrode finger opposite to the first dummy electrode finger; the second end is the end of the first electrode finger adjacent to the first dummy electrode finger; and the fourth end is the end of the second electrode finger adjacent to the second dummy electrode finger.

[0014] The material density of the first end and the third end is the first density;

[0015] The material density of the first electrode body, the second end, the second electrode body, and the fourth end is the second density.

[0016] Optionally, the first electrode finger includes a first end, a first electrode body, and a second end; the second electrode finger includes a third end, a second electrode body, and a fourth end; the first end is the end of the first electrode finger opposite to the second dummy electrode finger; the third end is the end of the second electrode finger opposite to the first dummy electrode finger; the second end is the end of the first electrode finger adjacent to the first dummy electrode finger; and the fourth end is the end of the second electrode finger adjacent to the second dummy electrode finger.

[0017] The material density of the second end and the fourth end is the same as the first density;

[0018] The material density of the first electrode body, the first end, the second electrode body, and the third end is the second density.

[0019] Optionally, the first electrode finger includes a first end, a first electrode body, and a second end; the second electrode finger includes a third end, a second electrode body, and a fourth end; the first end is the end of the first electrode finger opposite to the second dummy electrode finger; the third end is the end of the second electrode finger opposite to the first dummy electrode finger; the second end is the end of the first electrode finger adjacent to the first dummy electrode finger; and the fourth end is the end of the second electrode finger adjacent to the second dummy electrode finger.

[0020] The material density of the first end, the second end, the third end, and the fourth end is the first density;

[0021] The material density of the first electrode body and the second electrode body is the second density.

[0022] Optionally, the first electrode finger includes a first end, a first electrode body, and a second end; the second electrode finger includes a third end, a second electrode body, and a fourth end; the first end is the end of the first electrode finger opposite to the second dummy electrode finger; the third end is the end of the second electrode finger opposite to the first dummy electrode finger; the second end is the end of the first electrode finger adjacent to the first dummy electrode finger; and the fourth end is the end of the second electrode finger adjacent to the second dummy electrode finger.

[0023] The material density of the portion of the first electrode body corresponding to the third end is the first density;

[0024] The material density of the portion of the second electrode body corresponding to the first end is the first density.

[0025] Optionally, the first busbar includes a first portion close to the first dummy electrode finger and a second portion away from the first dummy electrode finger, wherein the material density of the second portion is less than that of the first portion;

[0026] And / or, the second busbar includes a third portion close to the second dummy electrode finger and a fourth portion away from the second dummy electrode finger, wherein the material density of the fourth portion is less than the material density of the third portion.

[0027] Optionally, the surface acoustic wave resonator further includes a first reflective grating and a second reflective grating;

[0028] Along the length of the first busbar, the first reflective grating and the second reflective grating are located on both sides of the transducer;

[0029] The first reflective grid includes a third busbar, a fourth busbar, and a plurality of first reflective sub-grids. A first end of the first reflective sub-grid is connected to the third busbar, and a second end of the first reflective sub-grid is connected to the fourth busbar. The material density of the first and second portions of the first reflective sub-grid is the first density. The first portion of the first reflective sub-grid is the portion corresponding to the first dummy electrode finger, and the second portion of the first reflective sub-grid is the portion corresponding to the second dummy electrode finger.

[0030] And / or, the second reflective grid includes a fifth bus bar, a sixth bus bar, and a plurality of second reflective sub-grids, wherein a first end of the second reflective sub-grid is connected to the fifth bus bar, and a second end of the second reflective sub-grid is connected to the sixth bus bar; the material density of the first and second portions of the second reflective sub-grid is the first density; wherein, the first portion of the second reflective sub-grid is the portion of the second reflective sub-grid corresponding to the first dummy electrode finger, and the second portion of the second reflective sub-grid is the portion of the second reflective sub-grid corresponding to the second dummy electrode finger.

[0031] Optionally, the materials of the first dummy electrode finger and the second dummy electrode finger include gold or copper, and the materials of the first electrode finger and the second electrode finger include aluminum.

[0032] According to another aspect of the present invention, a filter is provided, the filter comprising a surface acoustic wave resonator as described in any embodiment of the present invention.

[0033] In the technical solution of this invention embodiment, the material density of the first dummy electrode finger and the second dummy electrode finger is a first density, and the material density of the first electrode finger and the second electrode finger is a second density, and the first density is greater than the second density. Therefore, during sound wave propagation, the wave speed at the first dummy electrode finger and the second dummy electrode finger is slower, and the wave speed at the first electrode finger and the second electrode finger is faster. The material density of the first busbar and the second busbar is, for example, equal to the second density, so the wave speed at the first busbar and the second busbar is also faster. Along the transverse length of the resonator, from the middle to the left or from the middle to the right, the wave speed changes from slow to fast, and then from slow to fast again. When the wave speed changes from slow to fast, reflection is more likely to occur, resulting in more sound wave reflection. This confines the transverse mode sound wave to the second slow sound speed region and attenuates it through multiple reflections, thereby suppressing the transverse mode sound wave and reducing the generation of transverse mode ripples. At the same time, because of the sound speed change interface, the amount of sound wave reflected towards the middle is increased, which can confine the main mode sound wave in the transducer and reduce transverse leakage. The technical solution of this invention solves the problems of large transverse mode ripple and excessive transverse leakage, and achieves the suppression of transverse mode ripple and reduction of energy loss without changing the volume of the resonator.

[0034] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the transducer structure in the prior art;

[0037] Figure 2 yes Figure 1 Corresponding wave velocity distribution diagram;

[0038] Figure 3 This is a schematic diagram of the structure of a surface acoustic wave resonator provided in an embodiment of the present invention;

[0039] Figure 4 yes Figure 3 Corresponding wave velocity distribution diagram;

[0040] Figure 5 This is the test admittance curve of the surface acoustic wave resonator provided in the embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0042] Figure 7 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0043] Figure 8 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0044] Figure 9 yes Figure 8 Corresponding wave velocity distribution diagram;

[0045] Figure 10 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0046] Figure 11 yes Figure 10 Corresponding wave velocity distribution diagram;

[0047] Figure 12 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0048] Figure 13 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0049] Figure 14This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0050] Figure 15 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0051] Figure 16 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Detailed Implementation

[0052] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0053] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the term "comprising" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0054] Figure 1 This is a schematic diagram of the transducer structure in the prior art, for reference. Figure 1 The transducer includes a first busbar 11 and a second busbar 12; it also includes: a first electrode finger 13 and a first dummy electrode finger 14 alternately arranged and connected to the first busbar 11; a second electrode finger 15 and a second dummy electrode finger 16 alternately arranged and connected to the second busbar 12; and the first electrode finger 13 and the second dummy electrode finger 16 are arranged opposite to each other, with a first gap between them; the second electrode finger 15 and the first dummy electrode finger 14 are arranged opposite to each other, with a second gap between them; the transducer can convert electrical signals into sound waves, or convert sound waves into electrical signals, thereby achieving energy conversion; Figure 2 yes Figure 1 For the corresponding wave velocity distribution diagram, please refer to... Figure 2Along the transverse length of the resonator, from the second electrode finger 15 to the first bus bar 11, or from the first electrode finger 13 to the second bus bar 12, the wave speed changes from slow to fast and then from fast to slow. There is less sound wave reflection, making it difficult to completely confine the sound wave in the transducer, resulting in greater transverse leakage. The transverse mode sound wave cannot be attenuated and transverse mode ripples are generated.

[0055] To address the aforementioned technical problems, embodiments of the present invention provide a surface acoustic wave resonator. Figure 3 This is a schematic diagram of the structure of a surface acoustic wave resonator provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the surface acoustic wave resonator includes a transducer 100; the transducer 100 includes a first busbar 110, a second busbar 120, a plurality of first electrode fingers 130, a plurality of first dummy electrode fingers 140, a plurality of second electrode fingers 150, and a plurality of second dummy electrode fingers 160; the first electrode fingers 130 and the first dummy electrode fingers 140 are arranged alternately and connected to the first busbar 110; the second electrode fingers 150 and the second dummy electrode fingers 160 are arranged alternately and connected to the second busbar 120; the first electrode fingers 130 and the first dummy electrode fingers 14 ... The first electrode finger 130 and the second dummy electrode finger 160 are arranged opposite each other, with a first gap between the first electrode finger 130 and the second dummy electrode finger 160. The second electrode finger 150 and the first dummy electrode finger 140 are arranged opposite each other, with a second gap between the second electrode finger 150 and the first dummy electrode finger 140. The material density of the first dummy electrode finger 140 and the second dummy electrode finger 160 is a first density, and the material density of the first electrode finger 130 and the second electrode finger 150 is a second density. The first density is greater than the second density.

[0056] The transducer is a device that converts electrical energy into acoustic energy. It can convert the electrical signal input to the surface acoustic wave resonator into an acoustic signal, or convert the acoustic signal into an electrical signal for output. The first busbar 110 is connected to the positive electrode, and the second busbar 120 is connected to the negative electrode, for example; or the first busbar 110 is connected to the negative electrode, and the second busbar 120 is connected to the positive electrode. When the first electrode finger 130 is connected to the first busbar 110 and the second electrode finger 150 is connected to the second busbar 120, a pressure difference is formed. Combined with the piezoelectric layer, an inverse piezoelectric effect is formed, converting the electrical signal into an acoustic signal; or, a direct piezoelectric effect is formed, converting the acoustic signal into an electrical signal. Thus, the filter made using the surface acoustic wave resonator can output an electrical signal of a specific frequency.

[0057] Specifically, the material density of the first dummy electrode finger 140 and the second dummy electrode finger 160 is a first density, and the material density of the first electrode finger 130 and the second electrode finger 150 is a second density, and the first density is greater than the second density. Therefore, during sound wave propagation, the wave speed at the first dummy electrode finger 140 and the second dummy electrode finger 160 is slower, while the wave speed at the first electrode finger 130 and the second electrode finger 150 is faster. For example, if the material density of the first busbar 110 and the second busbar 120 is equal to the second density, then the wave speed at the first busbar 110 and the second busbar 120 is also faster. Figure 4 yes Figure 3 The corresponding wave velocity distribution diagram is as follows: Figure 4 As shown, along the transverse length of the resonator, from the second electrode finger 150 to the first bus bar 110, or from the first electrode finger 130 to the second bus bar 120, the wave velocity changes from slow to fast, and then from slow to fast again. When the wave velocity changes from slow to fast, reflection is more likely to occur, resulting in more sound wave reflection. This confines the transverse mode sound wave to the second slow sound velocity region, causing multiple reflections and attenuation, thereby suppressing the transverse mode sound wave and reducing the generation of transverse mode ripples. At the same time, because of the sound velocity change interface, the amount of sound wave reflected towards the middle is increased, which can confine the main mode sound wave within the transducer and reduce transverse leakage.

[0058] For example, Figure 5 The test admittance curve of the surface acoustic wave resonator provided in the embodiments of the present invention is shown below. Figure 5 As shown, curve ① is Figure 3 The admittance curve of the surface acoustic wave resonator, curve ② is Figure 1 The admittance curve of a surface acoustic wave resonator, from Figure 5 As can be seen from the data, curve ① has fewer transverse mode ripples, while curve ② has more transverse mode ripples. Therefore, the surface acoustic wave resonator provided in this embodiment can better suppress transverse mode ripples, reduce transverse leakage, and improve the accuracy of the surface acoustic wave resonator.

[0059] Furthermore, the lengths of the first dummy electrode finger 140 and the second dummy electrode finger 160 are, for example, 0.2 to 2 times the wavelength of the surface acoustic wave. The specific lengths of the first dummy electrode finger 140 and the second dummy electrode finger 160 can be determined according to the actual situation, and this embodiment does not limit them.

[0060] It should be noted that during the design and manufacturing process, the first dummy electrode finger 140 and the first bus bar 110 can overlap, and the second dummy electrode finger 160 and the second bus bar 120 can overlap. This can prevent the first dummy electrode finger 140 from separating from the first bus bar 110, and prevent the second dummy electrode finger 160 from separating from the second bus bar 120, thereby ensuring the stability of the surface acoustic wave resonator. Furthermore, the overlapping parts have virtually no impact on the main mode wave of the resonator, so the overlapping parts will not affect the performance of the surface acoustic wave resonator.

[0061] In this embodiment, the material density of the first dummy electrode finger and the second dummy electrode finger is a first density, and the material density of the first electrode finger and the second electrode finger is a second density, and the first density is greater than the second density. Therefore, during sound wave propagation, the wave speed at the first dummy electrode finger and the second dummy electrode finger is slower, and the wave speed at the first electrode finger and the second electrode finger is faster. The material density of the first busbar and the second busbar is, for example, equal to the second density, so the wave speed at the first busbar and the second busbar is also faster. Along the transverse length of the resonator, from the middle to the left or from the middle to the right, the wave speed changes from slow to fast, and then from slow to fast again. When the wave speed changes from slow to fast, reflection is more likely to occur, resulting in more sound wave reflection. This confines the transverse mode sound wave to the second slow sound speed region and attenuates it through multiple reflections, thereby suppressing the transverse mode sound wave and reducing the generation of transverse mode ripples. At the same time, because of the sound speed change interface, the amount of sound wave reflected towards the middle is increased, which can confine the main mode sound wave in the transducer and reduce transverse leakage. The technical solution of this embodiment solves the problems of large transverse mode ripple and excessive transverse leakage, and achieves the suppression of transverse mode ripple and reduction of energy loss without changing the volume of the resonator.

[0062] Based on the above technical solution, optionally, the materials of the first dummy electrode finger 140 and the second dummy electrode finger 160 include gold or copper, and the materials of the first electrode finger 130 and the second electrode finger 150 include aluminum.

[0063] Specifically, the materials of the first dummy electrode finger 140 and the second dummy electrode finger 160 include gold or copper. Gold and copper have higher densities, which can reduce the wave speed of sound at the first dummy electrode finger 140 and the second dummy electrode finger 160. The materials of the first electrode finger 130 and the second electrode finger 150 include aluminum. The materials of the first electrode finger 130 and the second electrode finger 150 can be aluminum or aluminum alloy. Aluminum has a lower density, which can increase the wave speed of sound at the first electrode finger 130 and the second electrode finger 150. The first dummy electrode finger 140, the second dummy electrode finger 160, the first electrode finger 130 and the second electrode finger 150 can also include other materials, which can be determined according to the actual situation, as long as the material density of the first dummy electrode finger 140 and the second dummy electrode finger 160 is greater than the material density of the first electrode finger 130 and the second electrode finger 150.

[0064] Figure 6 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 6 The width of the first dummy electrode finger 140 and the second dummy electrode finger 160 is the first width d1, and the width of the first electrode finger 130 and the second electrode finger 150 is the second width d2; the first width d1 is greater than or equal to the second width d2.

[0065] Specifically, when the first width d1 is greater than the second width d2, the widths of the first dummy electrode finger 140 and the second dummy electrode finger 160 are larger, which can further reduce the wave velocity of the sound wave at the lateral length positions corresponding to the first dummy electrode finger 140 and the second dummy electrode finger 160. This results in a larger wave velocity difference between the first dummy electrode finger 140 and the second electrode finger 150, and a larger wave velocity difference between the second dummy electrode finger 160 and the first electrode finger 130. This can further enhance the reflection of the sound wave, confining more lateral mode sound waves to the second slow wave region while confining the main mode sound wave to the surface acoustic wave resonator, reducing lateral leakage, and further reducing the generation of lateral mode ripples.

[0066] For example, the width of the first dummy electrode finger 140 and the second dummy electrode finger 160 can be, for example, 1.2 times that of the first electrode finger 130 and the second electrode finger 150. Wider first dummy electrode fingers 140 and second dummy electrode fingers 160 will further reduce the wave velocity of surface acoustic waves. However, the equipment accuracy will limit the minimum gap between the first dummy electrode fingers 140 and the second dummy electrode fingers 160. The width of the first dummy electrode fingers 140 and the second dummy electrode fingers 160 cannot be too large. Therefore, the width of the first dummy electrode fingers 140 and the second dummy electrode fingers 160 needs to be adjusted according to the actual process conditions.

[0067] Figure 7This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 7 The first electrode finger 130 includes a first end 131, a first electrode body 132, and a second end 133. The second electrode finger 150 includes a third end 151, a second electrode body 152, and a fourth end 153. The first end 131 is the end of the first electrode finger 130 opposite to the second dummy electrode finger 160, and the third end 151 is the end of the second electrode finger 150 opposite to the first dummy electrode finger 140. The second end 133 is the end of the first electrode finger 130 adjacent to the first dummy electrode finger 140, and the fourth end 153 is the end of the second electrode finger 150 adjacent to the second dummy electrode finger 160. The material density of the first end 131 and the third end 151 is a first density. The material density of the first electrode body 132, the second end 133, the second electrode body 152, and the fourth end 153 is a second density.

[0068] Specifically, the materials of the first end 131 of the first electrode finger 130 and the third end 151 of the second electrode finger 150 are, for example, the same as the materials of the first dummy electrode finger 140 and the second dummy electrode finger 160. The materials of the first dummy electrode finger 140, the second dummy electrode finger 160, the first end 131 of the first electrode finger 130, and the third end 151 of the second electrode finger 150 are, for example, gold or copper. The materials of the first electrode body 132, the second end 133, the second electrode body 152, and the fourth end 153 are, for example, aluminum. The materials of the first end 131 and the third end 152 are... The material density of part 151 is relatively high, the wave velocity at the first end 131 and the third end 151 is relatively low, while the wave velocity in the gap between the first end 131 and the second dummy electrode finger 160 is relatively high, forming a wave velocity change of "fast-slow-fast-slow-fast"; and the wave velocity difference in the gap between the first end 131 and the second dummy electrode finger 160 is relatively large, which can further enhance the reflection of sound waves, confine more transverse mode sound waves to the second and third slow wave regions, and further reduce the generation of transverse mode ripples; at the same time, the main mode sound waves are confined in the surface acoustic wave resonator, reducing transverse leakage.

[0069] Furthermore, the lengths of the first end 131 and the third end 151 are, for example, 0.2-1 times the wavelength of the surface acoustic wave. The specific lengths of the first end 131 and the third end 151 can be determined according to the actual situation, and this embodiment does not limit them. When fabricating the surface acoustic wave resonator, a photolithography process can be performed first to fabricate the first busbar 110, the second busbar 120, the first electrode body 132 and the second end 133 of the first electrode finger 130, and the second electrode body 152 and the fourth end 153 of the second electrode finger 150; then a photolithography process can be performed to form the first end 131 of the first electrode finger 130, the third end 151 of the second electrode finger 150, the first dummy electrode finger 140, and the second dummy electrode finger 160. The lengths of the second end 133 and the fourth end 153 are, for example, equal to the lengths of the first dummy electrode finger 140 and the second dummy electrode finger 160, such that in the transverse length direction of the resonator, the position corresponding to the second end 133 is the same as the transverse length position corresponding to the first dummy electrode finger 140, and the position corresponding to the fourth end 153 is the same as the transverse length position corresponding to the second dummy electrode finger 160, thereby further reducing the wave velocity at the transverse length positions corresponding to the first dummy electrode finger 140 and the second dummy electrode finger 160.

[0070] Figure 8 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 8 The first electrode finger 130 includes a first end 131, a first electrode body 132, and a second end 133. The second electrode finger 150 includes a third end 151, a second electrode body 152, and a fourth end 153. The first end 131 is the end of the first electrode finger 130 opposite to the second dummy electrode finger 160, and the third end 151 is the end of the second electrode finger 150 opposite to the first dummy electrode finger 140. The second end 133 is the end of the first electrode finger 130 adjacent to the first dummy electrode finger 140, and the fourth end 153 is the end of the second electrode finger 150 adjacent to the second dummy electrode finger 160. The material density of the second end 133 and the fourth end 153 is a first density. The material density of the first electrode body 132, the first end 131, the second electrode body 152, and the third end 151 is a second density.

[0071] Specifically, the materials of the second end 133 of the first electrode finger 130 and the fourth end 153 of the second electrode finger 150 are, for example, the same as the materials of the first dummy electrode finger 140 and the second dummy electrode finger 160. The materials of the first dummy electrode finger 140, the second dummy electrode finger 160, the second end 133 of the first electrode finger 130 and the fourth end 153 of the second electrode finger 150 are, for example, gold or copper. The materials of the first electrode body 132, the first end 131, the second electrode body 152 and the third end 151 are, for example, aluminum. The materials of the first end 131 and the third end 151 have a higher material density, which makes the wave velocity corresponding to the first dummy electrode finger 140 and the second dummy electrode finger 160 lower in the transverse length direction of the resonator, resulting in a larger wave velocity difference. This can further enhance the reflection of the sound wave, confine more transverse mode sound waves to the second slow wave region while confining the main mode sound wave in the surface acoustic wave resonator, reducing transverse leakage and further reducing the generation of transverse mode ripples.

[0072] Figure 9 yes Figure 8 The corresponding wave velocity distribution diagram is as follows: Figure 9 As shown, along the transverse length of the resonator, from the second electrode finger 150 to the first bus bar 110, or from the first electrode finger 130 to the second bus bar 120, the wave velocity changes from slow to fast, and then from slow to fast again, with a large wave velocity difference. This results in more sound wave reflections, increasing the amount of sound wave reflection towards the center. This confines more transverse mode sound waves to the second slow wave region while confining the main mode sound waves within the surface acoustic wave resonator, reducing transverse leakage and further reducing the generation of transverse mode ripples.

[0073] Figure 10 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 10 The first electrode finger 130 includes a first end 131, a first electrode body 132, and a second end 133. The second electrode finger 150 includes a third end 151, a second electrode body 152, and a fourth end 153. The first end 131 is the end of the first electrode finger 130 opposite to the second dummy electrode finger 160, and the third end 151 is the end of the second electrode finger 150 opposite to the first dummy electrode finger 140. The second end 133 is the end of the first electrode finger 130 adjacent to the first dummy electrode finger 140, and the fourth end 153 is the end of the second electrode finger 150 adjacent to the second dummy electrode finger 160. The material density of the first end 131, the second end 133, the third end 151, and the fourth end 153 is a first density. The material density of the first electrode body 132 and the second electrode body 152 is a second density.

[0074] Specifically, the materials of the first end 131 and second end 133 of the first electrode finger 130, and the third end 151 and fourth end 153 of the second electrode finger 150 are, for example, the same as the materials of the first dummy electrode finger 140 and the second dummy electrode finger 160. The materials of the first dummy electrode finger 140, the second dummy electrode finger 160, the first end 131 and second end 133 of the first electrode finger 130, and the third end 151 and fourth end 153 of the second electrode finger 150 are, for example, gold or copper. The materials of the first electrode body 132 and the second electrode body 152 are, for example, aluminum. Therefore, the materials of the first end 131, the second end 133, the third end 151, and the fourth end 153 are... The material density is relatively high, resulting in lower wave velocities at the first end 131 and the third end 151, while the gap wave velocity between the first end 131 and the second dummy electrode finger 160 is relatively high, forming a "fast-slow-fast-slow-fast" wave velocity variation. Furthermore, the higher material density at the first end 131 and the third end 151 results in even lower wave velocities corresponding to the first dummy electrode finger 140 and the second dummy electrode finger 160 in the transverse length direction of the resonator, leading to a larger wave velocity difference. This further enhances the reflection of sound waves, confining more transverse mode sound waves to the second and third slow wave regions, and further reducing the generation of transverse mode ripples. Simultaneously, it confines the main mode sound waves within the surface acoustic wave resonator, reducing transverse leakage.

[0075] Figure 11 yes Figure 10 The corresponding wave velocity distribution diagram is as follows: Figure 11 As shown, along the transverse length of the resonator, from the third end 151 to the first busbar 110, or from the first end 131 to the second busbar 120, the wave velocity changes from slow to fast, and then from slow to fast again, with a large wave velocity difference. This results in more acoustic wave reflections, confining more transverse mode acoustic waves to the second and third slow wave regions, further reducing the generation of transverse mode ripples. At the same time, it confines the main mode acoustic waves within the surface acoustic wave resonator, reducing transverse leakage.

[0076] It should be noted that during design and manufacturing, the first dummy electrode finger 140 and the first busbar 110 can overlap, and the second dummy electrode finger 160 and the second busbar 120 can overlap. This can prevent the first dummy electrode finger 140 from separating from the first busbar 110, and the second dummy electrode finger 160 from separating from the second busbar 120, thereby ensuring the stability of the surface acoustic wave resonator. Alternatively, the first end 131 and the first electrode body 132 can overlap, and the third end 151 and the second electrode body 152 can overlap. This can prevent the first end 131 and the first electrode body 132 from separating, and the third end 151 and the second electrode body 152 from separating, thereby ensuring the stability of the surface acoustic wave resonator. Furthermore, the overlapping parts have virtually no impact on the main mode wave of the resonator, so the overlapping parts will not affect the performance of the surface acoustic wave resonator. It should be noted that the overlapping portion will reduce the effective length of the first electrode finger 130, the first dummy electrode finger 140, the second electrode finger 150, and the second dummy electrode finger 160. Therefore, the length of the overlapping portion needs to be considered during the design.

[0077] Figure 12 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 12 The first electrode finger 130 includes a first end 131, a first electrode body 132, and a second end 133. The second electrode finger 150 includes a third end 151, a second electrode body 152, and a fourth end 153. The first end 131 is the end of the first electrode finger 130 opposite to the second dummy electrode finger 160, and the third end 151 is the end of the second electrode finger 150 opposite to the first dummy electrode finger 140. The second end 133 is the end of the first electrode finger 130 adjacent to the first dummy electrode finger 140, and the fourth end 153 is the end of the second electrode finger 150 adjacent to the second dummy electrode finger 160. The material density of the portion of the first electrode body 132 corresponding to the third end 151 is a first density. The material density of the portion of the second electrode body 152 corresponding to the first end 131 is a first density.

[0078] Specifically, the material of the part of the second electrode body 152 corresponding to the first end 131 is, for example, gold or copper, and the material of the part of the first electrode body 132 corresponding to the third end 151 is, for example, gold or copper. In the transverse length direction of the resonator, the wave velocity at the first end 131 and the third end 151 is smaller, while the gap wave velocity between the first end 131 and the second dummy electrode finger 160 is larger, resulting in a larger wave velocity difference, forming a "fast-slow-fast-slow-fast" pattern. This can further enhance the reflection of sound waves, confine more transverse mode sound waves to the second and third slow wave regions, and confine the main mode sound waves to the surface acoustic wave resonator, reducing transverse leakage and further reducing the generation of transverse mode ripples.

[0079] Figure 13 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 13 The first busbar 110 includes a first portion 111 near the first dummy electrode finger 140 and a second portion 112 away from the first dummy electrode finger 140, wherein the material density of the second portion 112 is less than the material density of the first portion 111; and / or, the second busbar 120 includes a third portion 121 near the second dummy electrode finger 160 and a fourth portion 122 away from the second dummy electrode finger 160, wherein the material density of the fourth portion 122 is less than the material density of the third portion 121.

[0080] Specifically, if the material of the first portion 111 near the first dummy electrode finger 140 is the same as that of the first dummy electrode finger 140, such as copper or gold, then the material density of the first portion 111 is relatively high, and the wave speed of the sound wave propagation in the first portion 111 is relatively low. On the other hand, the material density of the second portion 112 is relatively low, such as aluminum or aluminum alloy, and the wave speed of the sound wave propagation in the second portion 112 is relatively high. Along the first portion 111 to the second portion 112, the wave speed can form a change from slow to fast, which can further enhance the reflection of the sound wave, confine more sound waves in the surface acoustic wave resonator, reduce transverse leakage, and further reduce the generation of transverse mode ripples. Similarly, if the material of the third part 121 near the second dummy electrode finger 160 is the same as that of the second dummy electrode finger 160, such as copper or gold, then the material density of the third part 121 is higher, and the wave speed of the sound wave propagation in the third part 121 is lower; while the material density of the fourth part 122 is lower, such as aluminum or aluminum alloy, and the wave speed of the sound wave propagation in the fourth part 122 is higher. Along the third part 121 to the fourth part 122, the wave speed can change from slow to fast, which can further enhance the reflection of the sound wave, confine more transverse mode sound waves to the second slow wave region while confining the main mode sound waves in the surface acoustic wave resonator, reducing transverse leakage, and further reducing the generation of transverse mode ripples.

[0081] Figure 14 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 14 The surface acoustic wave resonator also includes a first reflective grating 170 and a second reflective grating 180; along the length direction of the first busbar 110, the first reflective grating 170 and the second reflective grating 180 are located on both sides of the transducer; the first reflective grating 170 includes a third busbar 171, a fourth busbar 172 and a plurality of first reflective sub-gratings 83, the first end of the first reflective sub-grating 173 is connected to the third busbar 171, and the second end of the first reflective sub-grating 173 is connected to the fourth busbar 172; the material density of the first portion 1731 and the second portion 1732 of the first reflective sub-grating 173 is a first density; wherein, the first portion 1731 of the first reflective sub-grating 173 is the portion of the first reflective sub-grating 173 corresponding to the first dummy electrode finger 140, and the second portion 173 of the first reflective sub-grating 173... Part 1732 is the part corresponding to the first reflective sub-gate 173 and the second dummy electrode finger 160; and / or, the second reflective gate 180 includes a fifth bus bar 181, a sixth bus bar 182 and a plurality of second reflective sub-gates 183, the first end of the second reflective sub-gate 183 is connected to the fifth bus bar 181, and the second end of the second reflective sub-gate 183 is connected to the sixth bus bar 182; the material density of the first part 1831 and the second part 1832 of the second reflective sub-gate 183 is a first density; wherein, the first part 1831 of the second reflective sub-gate 183 is the part corresponding to the first dummy electrode finger 140, and the second part 1832 of the second reflective gate 183 is the part corresponding to the second reflective gate 183 and the second dummy electrode finger 160.

[0082] Specifically, the first reflective grating 170 and the second reflective grating 180 can reflect sound waves, confining them inside the surface acoustic wave resonator and reducing lateral leakage. Furthermore, if the materials of the first portion 1731 and the second portion 1732 of the first reflective sub-grid 173 and the first portion 1831 and the second portion 1832 of the second reflective sub-grid 183 are, for example, the same as the material of the first dummy electrode finger 140, such as gold or copper, then the density of the first portion 1731 and the second portion 1732 of the first reflective sub-grid 173 and the first portion 1831 and the second portion 1832 of the second reflective sub-grid 183 is relatively large, and the wave speed of sound wave propagation at the first portion 1731 and the second portion 1732 of the first reflective sub-grid 173 and the first portion 1831 and the second portion 1832 of the second reflective sub-grid 183 is relatively small. Therefore, in the transverse length direction of the resonator, the wave speed at the first dummy electrode finger 140 and the second dummy electrode finger 160 is relatively small, which can further enhance the reflection of sound waves, confine more transverse mode sound waves to the second slow wave region, and confine the main mode sound waves in the surface acoustic wave resonator, reduce transverse leakage, and further reduce the generation of transverse mode ripples.

[0083] Figure 15 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 15 The materials of the second end 133 of the first electrode finger 130 and the fourth end 153 of the second electrode finger 150 are, for example, the same as the materials of the first dummy electrode finger 140 and the second dummy electrode finger 160. The materials of the first dummy electrode finger 140, the second dummy electrode finger 160, the second end 133 of the first electrode finger 130, and the fourth end 153 of the second electrode finger 150 are, for example, gold or copper. The materials of the first electrode body 132, the first end 131, the second electrode body 152, and the third end 151 are, for example, aluminum, thus the first end 131 and the third end 151 have a higher material density. Furthermore, the materials of the first portion 1731 and the second portion 1732 of the first reflector grid 173, and the first portion 1831 and the second portion 1832 of the second reflector grid 183 are, for example, the same as the materials of the first dummy electrode finger 140 and the second dummy electrode finger 160. If the materials of 40 are the same, such as gold or copper, then the density of the first part 1731 and the second part 1732 of the first reflector grating 173 and the first part 1831 and the second part 1832 of the second reflector grating 183 is relatively large, and the wave speed of the sound wave propagation of the first part 1731 and the second part 1732 of the first reflector grating 173 and the first part 1831 and the second part 1832 of the second reflector grating 183 is relatively small. This results in a lower wave speed corresponding to the first dummy electrode finger 140 and the second dummy electrode finger 160 in the transverse length direction of the resonator, resulting in a larger wave speed difference. This can further enhance the reflection of the sound wave, confine more transverse mode sound waves to the second slow wave region, and confine the main mode sound wave to the surface acoustic wave resonator, reducing transverse leakage and further reducing the generation of transverse mode ripples.

[0084] Figure 16 This is a schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention. Optionally, refer to... Figure 16The materials of the first end 131 and second end 133 of the first electrode finger 130, and the third end 151 and fourth end 153 of the second electrode finger 150 are, for example, the same as the materials of the first dummy electrode finger 140 and the second dummy electrode finger 160. The materials of the first dummy electrode finger 140, the second dummy electrode finger 160, the first end 131 and second end 133 of the first electrode finger 130, and the third end 151 and fourth end 153 of the second electrode finger 150 are, for example, gold or copper. The materials of the first electrode body 132 and the second electrode body 152 are, for example, aluminum. Therefore, the material density of the first end 131, the second end 133, the third end 151, and the fourth end 153 is relatively high, resulting in a lower wave velocity at the first end 131 and the third end 151, while the gap wave velocity between the first end 131 and the second dummy electrode finger 160 is relatively high. Furthermore, the higher material density of the first end 131 and the third end 151 results in a higher wave velocity corresponding to the first dummy electrode finger 140 and the second dummy electrode finger 160 in the transverse length direction of the resonator. The density of the first portion 1731 and the second portion 1732 of the first reflective sub-grid 173 and the first portion 1831 and the second portion 1832 of the second reflective sub-grid 183 is relatively high. Furthermore, the materials of the first portion 1731 and the second portion 1732 of the first reflective sub-grid 173 and the first portion 1831 and the second portion 1832 of the second reflective sub-grid 183 are similar to those of the first dummy electrode finger 140, such as gold or copper. This results in a lower wave velocity for the sound waves propagating from the first portion 1731 and the second portion 1732 of the first reflective sub-grid 173 and the first portion 1831 and the second portion 1832 of the second reflective sub-grid 183. Consequently, the wave velocities corresponding to the first dummy electrode finger 140 and the second dummy electrode finger 160 are even lower in the transverse length direction of the resonator, leading to a larger wave velocity difference. This further enhances the reflection of sound waves, confining more transverse mode sound waves to the second and third slow-wave regions while confining the main mode sound waves within the surface acoustic wave resonator, reducing transverse leakage, and further reducing the generation of transverse mode ripples.

[0085] The technical solution of this invention also provides a filter, which includes the surface acoustic wave resonator described in any of the above embodiments. The implementation principle and technical effect of the filter provided in this embodiment are similar to those of the above embodiments, and will not be repeated here.

[0086] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A surface acoustic wave resonator, characterized in that, Including transducers; The transducer includes a first busbar, a second busbar, a plurality of first electrode fingers, a plurality of first dummy electrode fingers, a plurality of second electrode fingers, and a plurality of second dummy electrode fingers; The first electrode finger and the first dummy electrode finger are arranged alternately and connected to the first busbar; The second electrode finger and the second dummy electrode finger are arranged alternately and connected to the second busbar; The first electrode finger and the second dummy electrode finger are arranged opposite to each other, and there is a first gap between the first electrode finger and the second dummy electrode finger. The second electrode finger and the first dummy electrode finger are arranged opposite to each other, and there is a second gap between the second electrode finger and the first dummy electrode finger. The material density of the first dummy electrode finger and the second dummy electrode finger is a first density, and the material density of the first electrode finger and the second electrode finger is a second density, wherein the first density is greater than the second density; The first busbar includes a first portion close to the first dummy electrode finger and a second portion away from the first dummy electrode finger, wherein the material density of the second portion is less than the material density of the first portion; and / or, the second busbar includes a third portion close to the second dummy electrode finger and a fourth portion away from the second dummy electrode finger, wherein the material density of the fourth portion is less than the material density of the third portion; The first dummy electrode is made of the same material as the first part, and the second dummy electrode is made of the same material as the third part.

2. The surface acoustic wave resonator according to claim 1, characterized in that, The width of the first dummy electrode finger and the second dummy electrode finger is a first width, and the width of the first electrode finger and the second electrode finger is a second width; the first width is greater than or equal to the second width.

3. The surface acoustic wave resonator according to claim 1, characterized in that, The first electrode finger includes a first end, a first electrode body, and a second end; the second electrode finger includes a third end, a second electrode body, and a fourth end. The first end is the end of the first electrode finger opposite to the second dummy electrode finger; the third end is the end of the second electrode finger opposite to the first dummy electrode finger; the second end is the end of the first electrode finger adjacent to the first dummy electrode finger; and the fourth end is the end of the second electrode finger adjacent to the second dummy electrode finger. The material density of the first end and the third end is the first density; The material density of the first electrode body, the second end, the second electrode body, and the fourth end is the second density.

4. The surface acoustic wave resonator according to claim 1, characterized in that, The first electrode finger includes a first end, a first electrode body, and a second end; the second electrode finger includes a third end, a second electrode body, and a fourth end. The first end is the end of the first electrode finger opposite to the second dummy electrode finger; the third end is the end of the second electrode finger opposite to the first dummy electrode finger; the second end is the end of the first electrode finger adjacent to the first dummy electrode finger; and the fourth end is the end of the second electrode finger adjacent to the second dummy electrode finger. The material density of the second end and the fourth end is the same as the first density; The material density of the first electrode body, the first end, the second electrode body, and the third end is the second density.

5. The surface acoustic wave resonator according to claim 1, characterized in that, The first electrode finger includes a first end, a first electrode body, and a second end; the second electrode finger includes a third end, a second electrode body, and a fourth end. The first end is the end of the first electrode finger opposite to the second dummy electrode finger; the third end is the end of the second electrode finger opposite to the first dummy electrode finger; the second end is the end of the first electrode finger adjacent to the first dummy electrode finger; and the fourth end is the end of the second electrode finger adjacent to the second dummy electrode finger. The material density of the first end, the second end, the third end, and the fourth end is the first density; The material density of the first electrode body and the second electrode body is the second density.

6. The surface acoustic wave resonator according to claim 1, characterized in that, The first electrode finger includes a first end, a first electrode body, and a second end; the second electrode finger includes a third end, a second electrode body, and a fourth end. The first end is the end of the first electrode finger opposite to the second dummy electrode finger; the third end is the end of the second electrode finger opposite to the first dummy electrode finger; the second end is the end of the first electrode finger adjacent to the first dummy electrode finger; and the fourth end is the end of the second electrode finger adjacent to the second dummy electrode finger. The material density of the portion of the first electrode body corresponding to the third end is the first density; The material density of the portion of the second electrode body corresponding to the first end is the first density.

7. The surface acoustic wave resonator according to any one of claims 1-6, characterized in that, The surface acoustic wave resonator further includes a first reflective grating and a second reflective grating; Along the length of the first busbar, the first reflective grating and the second reflective grating are located on both sides of the transducer; The first reflective grid includes a third busbar, a fourth busbar, and a plurality of first reflective sub-grids. A first end of the first reflective sub-grid is connected to the third busbar, and a second end of the first reflective sub-grid is connected to the fourth busbar. The material density of the first and second portions of the first reflective sub-grid is the first density. The first portion of the first reflective sub-grid is the portion corresponding to the first dummy electrode finger, and the second portion of the first reflective sub-grid is the portion corresponding to the second dummy electrode finger. And / or, the second reflective grid includes a fifth bus bar, a sixth bus bar, and a plurality of second reflective sub-grids, wherein a first end of the second reflective sub-grid is connected to the fifth bus bar, and a second end of the second reflective sub-grid is connected to the sixth bus bar; the material density of the first and second portions of the second reflective sub-grid is the first density; wherein, the first portion of the second reflective sub-grid is the portion of the second reflective sub-grid corresponding to the first dummy electrode finger, and the second portion of the second reflective sub-grid is the portion of the second reflective sub-grid corresponding to the second dummy electrode finger.

8. The surface acoustic wave resonator according to claim 1, characterized in that, The materials of the first dummy electrode finger and the second dummy electrode finger include gold or copper, and the materials of the first electrode finger and the second electrode finger include aluminum.

9. A filter, characterized in that, The surface acoustic wave resonator includes any one of claims 1-8.

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