Elastic wave device
By introducing high-velocity and low-velocity regions into the IDT electrodes and adjusting the duty cycle of the electrode fingers, the transverse energy leakage problem of the surface acoustic wave resonator was solved, and the Q value and filtering performance of the resonator were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2026-03-06
AI Technical Summary
In the prior art, the propagation of acoustic wave components in the Y direction of surface acoustic wave resonators leads to transverse energy leakage, resulting in a decrease in the resonator's quality factor Q and affecting the filtering performance of elastic wave devices.
By introducing high-velocity and low-velocity regions into the IDT electrodes and adjusting the duty cycle of the electrode fingers, especially the duty cycle of the transverse and longitudinal virtual electrode fingers, the sound velocity difference is increased, thus suppressing transverse energy leakage.
It effectively suppressed the transverse energy leakage of the resonator, improved the Q value of the resonator, and enhanced the filtering performance of the elastic wave device.
Smart Images
Figure CN223978627U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and in particular to an elastic wave device. Background Technology
[0002] A surface acoustic wave (SAW) resonator is an elastic wave device that utilizes the properties of piezoelectric materials to convert electrical signals into acoustic signals. Its core lies in its ability to convert electrical energy into mechanical energy and then back into electrical energy using the piezoelectric effect of the material. Its basic structure includes a piezoelectric substrate and an interdigital transducer (IDT) deposited on its surface. When an electrical signal is applied to the IDT, an elastic wave, i.e., a surface acoustic wave, is generated on the surface of the piezoelectric material and propagates in a specific direction. In this process, the IDT not only acts as a transducer but also as a reflector, concentrating the acoustic wave energy within a certain frequency range through multiple reflections, thereby achieving resonance.
[0003] However, in practical applications, surface acoustic waves (SAWs) do not propagate entirely along the IDT aperture direction (usually defined as the X-axis direction). In fact, there is also an acoustic wave component along the direction perpendicular to the IDT aperture (Y-axis direction). This acoustic wave component leaks along the busbars at both ends (lateral energy leakage), causing a decrease in the resonator's quality factor (Q value), increasing the insertion loss during operation, and thus affecting the filtering performance of the SAW device.
[0004] Current technologies such as pseudo-finger structures and piston structures mainly suppress transverse energy leakage of resonators by adding multiple discontinuous sound velocity regions, but the suppression effect is limited.
[0005] There is still no good solution to the problem that the quality factor Q of the resonator decreases due to the lateral energy leakage of the sound wave component propagating in the Y direction to both ends, which in turn affects the filtering performance of the elastic wave device. Utility Model Content
[0006] This application provides an elastic wave device to solve the problem that the quality factor Q of the resonator decreases due to the lateral energy leakage of the acoustic wave component propagating in the Y direction to both ends, thereby affecting the filtering performance of the elastic wave device.
[0007] In one aspect, this embodiment provides an elastic wave device, including a piezoelectric substrate;
[0008] An IDT electrode is located on the main surface of the piezoelectric substrate; wherein the IDT electrode includes a busbar, electrode fingers, and extended electrode fingers; the busbar includes a first busbar and a second busbar disposed opposite to each other; the electrode fingers include a first electrode finger located on the first busbar and a second electrode finger located on the second busbar, and the area where the first electrode fingers and the second electrode fingers are alternately distributed is an interlaced region; the length direction of the electrode fingers is a first direction, the length direction of the busbar is a second direction, and the first direction is perpendicular to the second direction;
[0009] The extended electrode fingers are located between the electrode fingers; each extended electrode finger includes a lateral virtual electrode finger and a longitudinal virtual electrode finger, the lateral virtual electrode fingers intersecting the longitudinal virtual electrode fingers; the longitudinal virtual electrode fingers are parallel to a first direction, and the lateral virtual electrode fingers are parallel to a second direction;
[0010] In the first direction, the region between the lateral virtual electrode finger and the busbar, and the region between the lateral virtual electrode finger and the tail end of the electrode finger opposite it are designated as high-sound speed regions. The duty cycle of the electrode finger in the high-sound speed region is different from that of the electrode finger in the interleaved region, so that the sound speed in the high-sound speed region is higher than that in the interleaved region.
[0011] In some of these embodiments, in the first direction, the longitudinal virtual electrode finger of the extended electrode finger is directly opposite one of the electrode fingers.
[0012] In some embodiments, the region between the lateral virtual electrode finger and the tail end of the opposing electrode finger includes:
[0013] In the first direction, the region between the lateral virtual electrode finger and the tail end of the longitudinal virtual electrode finger that intersects with it; and the region between the longitudinal virtual electrode finger and the tail end of the electrode finger directly opposite it.
[0014] In some of these embodiments, the duty cycle of the electrode fingers varies in different hypersonic regions.
[0015] In some embodiments, the interlaced region includes a central region and an edge region, wherein the duty cycle of the electrode fingers in the edge region is greater than the duty cycle of the electrode fingers in the central region.
[0016] In some of these embodiments, the extended electrode fingers have at least two of the lateral virtual electrode fingers.
[0017] In some embodiments, the hypersonic region also includes the region between two adjacent lateral virtual electrode fingers.
[0018] In some of these embodiments, the length and width of the lateral virtual electrode fingers on the extended electrode fingers are different.
[0019] In some of these embodiments, the lateral virtual electrode finger is connected to only one adjacent electrode finger.
[0020] In some of these embodiments, in the second direction, the lateral virtual electrode finger has a protrusion on both the electrode finger to which it is connected and the longitudinal virtual electrode finger.
[0021] Compared with related technologies, this embodiment provides an elastic wave device, including a piezoelectric substrate; an IDT electrode located on the main surface of the piezoelectric substrate; wherein the IDT electrode includes a bus bar and electrode fingers; the bus bar includes a first bus bar and a second bus bar arranged opposite to each other; the electrode fingers include a first electrode finger located on the first bus bar and a second electrode finger located on the second bus bar, and the area where the first electrode fingers and the second electrode fingers are alternately distributed is an alternating region; the length direction of the electrode fingers is a first direction, the length direction of the bus bar is a second direction, and the first direction is perpendicular to the second direction; extended electrode fingers located between the electrode fingers; each extended electrode finger includes a transverse virtual electrode finger and a longitudinal virtual electrode finger, the transverse virtual electrode finger intersecting the longitudinal virtual electrode finger; the longitudinal virtual electrode finger is parallel to the first direction, and the transverse virtual electrode finger is parallel to the second direction; wherein, in the first direction, the area between the transverse virtual electrode finger and the bus bar, and the area between the transverse virtual electrode finger and the tail end of its opposite electrode finger are high-speed regions, and the duty cycle of the electrode fingers in the high-speed regions is less than the duty cycle of the electrode fingers in the alternating regions. The aforementioned elastic wave device effectively suppresses lateral energy leakage of the resonator, thereby increasing the Q value of the resonator and improving the filtering performance of the elastic wave device.
[0022] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description
[0023] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.
[0024] Figure 1 This is a schematic diagram of the structure of the elastic wave device according to the first embodiment of this application;
[0025] Figure 2 The graph shows the duty cycle and sound velocity of the electrode fingers and longitudinal virtual electrode fingers of the elastic wave device in the first embodiment.
[0026] Figure 3This is a schematic diagram of the sound velocity distribution in the first direction of the elastic wave device according to the first embodiment;
[0027] Figure 4 This is a partially enlarged view of region H2 in the elastic wave device of the first embodiment;
[0028] Figure 5 The graph shows the characteristic curves of the duty cycle of the electrode fingers and longitudinal virtual electrode fingers 232 in region H2 of the elastic wave device in the first embodiment versus the sound velocity in region H2.
[0029] Figure 6 This is a schematic diagram of the structure of the elastic wave device according to the second embodiment of this application;
[0030] Figure 7 This is a schematic diagram of the structure of the elastic wave device according to the third embodiment of this application;
[0031] Figure 8 This is a schematic diagram of the sound velocity distribution in the first direction for the elastic wave device of the third embodiment;
[0032] Figure 9 This is a schematic diagram of the structure of the elastic wave device according to the fourth embodiment of this application;
[0033] Figure 10 This is a schematic diagram of the structure of the elastic wave device according to the fifth embodiment of this application;
[0034] Figure 11 This is a schematic diagram of the structure of the elastic wave device according to the sixth embodiment of this application;
[0035] Figure 12 This is a schematic diagram of the structure of the elastic traveling wave device according to a preferred embodiment of this application;
[0036] Figure 13 A schematic diagram of the structure of the elastic wave device for comparison;
[0037] Figure 14 Sound velocity distribution diagrams of the elastic wave devices in the preferred embodiments and comparative examples;
[0038] Figure 15 Admittance-frequency response diagrams of the elastic wave devices of the preferred embodiments and comparative examples;
[0039] Figure 16 The Q-frequency response diagrams of the elastic wave devices in the preferred embodiments and comparative examples are shown.
[0040] In the figure: 100, piezoelectric substrate; 200, IDT electrode; 210a, first busbar; 210b, second busbar; 220a, first electrode finger; 220b, second electrode finger; 230, extended electrode finger; 231, lateral virtual electrode finger; 232, vertical virtual electrode finger. Detailed Implementation
[0041] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.
[0042] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning as understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these,” used in this application, do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to such processes, methods, products, or devices. The terms “connected,” “linked,” and “coupled,” used in this application, are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. The term “multiple” used in this application refers to two or more. The "and / or" operator describes the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: A alone, A and B simultaneously, and B alone. Typically, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," and "third," etc., used in this application are merely for distinguishing similar objects and do not represent a specific ordering of the objects.
[0043] The following is based on Figures 1 to 16 The elastic wave device of this application will be described.
[0044] The embodiments are described below with reference to the accompanying drawings. In each drawing, the same or corresponding parts are labeled with the same reference numerals. For parts that are described repeatedly, they will be appropriately simplified or omitted.
[0045] The duty cycle of the IDT electrode is defined as the ratio of the length (i.e., linewidth) of the IDT electrode finger in the X direction to 0.5 times the wavelength of the sound wave. The wavelength of the sound wave is the wavelength of the elastic wave excited by the IDT electrode, denoted as λ. By adjusting the duty cycle of the electrode finger to adjust the sound wave velocity, the transverse energy leakage of the elastic wave device can be effectively suppressed, thereby better controlling the frequency response of the elastic wave device.
[0046] Figure 1 This is a schematic diagram of the structure of the elastic wave device according to the first embodiment of this application, as shown below. Figure 1As shown, the elastic wave device of this embodiment includes a piezoelectric substrate 100, the constituent material of which includes piezoelectric materials such as lithium tantalate or lithium niobate; an IDT electrode 200 located on the main surface of the piezoelectric substrate 100, wherein the IDT electrode 200 includes a bus bar, electrode fingers, and extended electrode fingers 230; the bus bar includes a first bus bar 210a and a second bus bar 210b disposed opposite to each other; the electrode fingers include a first electrode finger 220a located on the first bus bar 210a and a second electrode finger 220b located on the second bus bar 210b, and the area where the first electrode finger 220a and the second electrode finger 220b are alternately distributed is an alternating region S. The length direction of the electrode fingers is a first direction, i.e. Figure 1 In the Y direction, the length direction of the busbar is the second direction, i.e. Figure 1 In the X-direction, the first direction is perpendicular to the second direction. Extended electrode fingers 230 are located between the electrode fingers; each extended electrode finger 230 includes a transverse virtual electrode finger 231 and a longitudinal virtual electrode finger 232, with the transverse virtual electrode finger 231 intersecting the longitudinal virtual electrode finger 232; the longitudinal virtual electrode finger 232 is parallel to the first direction, and the transverse virtual electrode finger 231 is parallel to the second direction. Additionally... Figure 1 L1 is the distribution area of the busbar in the first direction; H1 is the area between the transverse virtual electrode finger 231 and the busbar in the first direction; L2 is the distribution area of the transverse virtual electrode finger 231 in the first direction; H2 is the area between the transverse virtual electrode finger 231 in the first direction and the tail end of its opposite electrode finger. The duty cycle of the electrode finger portion in H1 and H2 is in the range of 0.2 to 0.45, which is smaller than the duty cycle of the electrode finger in the above-mentioned interlaced region S.
[0047] Figure 2 The graph shows the duty cycle versus sound velocity for the electrode fingers and longitudinal virtual electrode fingers of the aforementioned elastic wave device, as shown below. Figure 2 As shown, the speed of sound is lowest at a duty cycle of 0.75, approximately 3870 m / s; when the duty cycle is less than 0.7, the speed of sound is inversely proportional to the duty cycle; when the duty cycle is greater than 0.75, the speed of sound is directly proportional to the duty cycle. According to... Figure 2 Regarding the characteristic curves of the duty cycle of the electrode fingers and the longitudinal virtual electrode fingers, in this embodiment, the duty cycle range of the electrode fingers in the interlaced region S of the elastic wave device is set to 0.4–0.55, the duty cycle range of the electrode fingers in regions H1 and H2 is 0.2–0.4, and the duty cycle range of the electrode fingers in region L2 is 0.6–0.75. It should be noted that in some other embodiments, the duty cycle of the electrode fingers and the longitudinal virtual electrode fingers 232 in at least one of the regions H1 and H2 is greater than 0.75, preferably in the range of 0.8–0.9.
[0048] Figure 3This is a schematic diagram of the sound velocity distribution in the first direction of the elastic wave device according to the first embodiment. Regions with sound velocities higher than those in the interlacing region S are designated as high-velocity regions, and regions with sound velocities lower than those in the interlacing region S are designated as low-velocity regions. Figure 3 As shown, the sound speeds in regions H1 and H2 of the IDT electrode 200 are higher than those in the interleaved region S, while the sound speeds in regions L1 and L2 are lower than those in the interleaved region S. Therefore, regions H1 and H2 are high-sound-speed regions, and regions L1 and L2 are low-sound-speed regions.
[0049] In summary, by setting the duty cycles of the electrode fingers in the high-velocity region of the elastic wave device to be different from those in the staggered region S, the velocity difference between the staggered region S and the high-velocity region, as well as the velocity difference between the low-velocity region and the high-velocity region, is increased, thereby suppressing the transverse energy leakage propagating in the Y direction and improving the Q value of the elastic wave device.
[0050] In some of these embodiments, such as Figure 2 As shown, the duty cycle of the longitudinal virtual electrode finger 232 also affects the sound speed in its region. The duty cycle of the longitudinal virtual electrode finger 232 is set to be different from that of the electrode finger in the interlaced region S. Preferably, the duty cycle of the longitudinal virtual electrode finger 232 is smaller than that of the electrode finger in the interlaced region S, so as to further increase the sound speed difference between the interlaced region S and the high sound speed region.
[0051] In some embodiments, the region between the lateral virtual electrode finger 231 and the tail end of its opposite electrode finger includes: in a first direction, the region between the lateral virtual electrode finger 231 and the tail end of its intersecting longitudinal virtual electrode finger 232; and the region between the tail end of the longitudinal virtual electrode finger 232 and the tail end of its directly opposite electrode finger.
[0052] Specifically, Figure 4 for Figure 1 A magnified view of part of region H2, as shown below. Figure 4 As shown, region H2 includes regions H2-1 and H2-2. Region H2-1 is the area between the tail ends of the transverse virtual electrode finger 231 and the longitudinal virtual electrode finger 232 that intersects it; region H2-2 is the gap area between the tail end of the longitudinal virtual electrode finger 232 and the tail end of the electrode finger 220a directly opposite it. Figure 2 It can be seen that the speed of sound in region H2-2 is higher than that in region H2-1. Figure 5 The graph shows the characteristic curves of the duty cycle of the electrode finger and the longitudinal virtual electrode finger 232 in region H2 versus the sound velocity in region H2, as shown below. Figure 5As shown, the duty cycle of the electrode finger and the longitudinal virtual electrode finger 232 in region H2 is inversely proportional to the speed of sound. Therefore, by adjusting the duty cycle of the electrode finger and the longitudinal virtual electrode finger 232 in region H2, the speed difference between region H2 and the staggered region S can be increased, thereby improving the Q value of the resonator. It should be noted that in some other embodiments, region H2 may not have H2-1, that is, the gap region H2-2 extends from the lateral virtual electrode finger 231 to the tail end of its directly opposite electrode finger 220a.
[0053] In some of these embodiments, the duty cycle of the electrode fingers varies in different hypersonic regions.
[0054] Specifically, Figure 6 This is a schematic diagram of the structure of the elastic wave device according to the second embodiment of this application, as shown below. Figure 6 As shown, the duty cycle of the electrode fingers in region H1 is 0.4, and the duty cycle of the electrode fingers in region H2 is 0.8. By adjusting the duty cycles of the electrode fingers in regions H1 and H2 respectively, the frequency response and parasitic response of the acoustic wave in these regions can be accurately controlled, thereby improving the transmission efficiency of the acoustic wave in the target mode of the elastic wave device and ensuring the integrity of the acoustic wave signal.
[0055] In some embodiments, the interleaved region S includes a central region and an edge region, wherein the duty cycle of the electrode fingers in the edge region is greater than that of the electrode fingers in the central region.
[0056] Specifically, Figure 7 This is a schematic diagram of the structure of the elastic wave device according to the third embodiment of this application, as shown below. Figure 7 As shown, the interlaced region S includes a central region S-1 and an edge region S-2. The duty cycle of the electrode fingers in region S-1 is 0.8–0.9, and the duty cycle of the electrode fingers in region S-2 is also 0.8–0.9. The corresponding sound velocity distribution diagram is shown below. Figure 8 As shown, by setting the duty cycle of the electrode fingers in the edge region to be greater than that in the center region, the transverse energy leakage of sound waves can be further suppressed.
[0057] In some of these embodiments, the extended electrode finger 230 has at least two lateral virtual electrode fingers 231.
[0058] Specifically, Figure 9 This is a schematic diagram of the structure of the elastic wave device according to the fourth embodiment of this application, as shown below. Figure 9 As shown, the extended electrode finger 230 has at least two transverse virtual electrode fingers 231. Figure 9 The right side shows the sound velocity distribution of the elastic wave device in the first direction. In this embodiment, by increasing the alternating structure of high and low sound velocity regions, the transverse energy leakage in the Y direction can be more effectively suppressed, thereby further improving the Q value of the elastic wave device.
[0059] In some of these embodiments, the hypersonic region also includes the region between two adjacent transverse virtual electrode fingers 231.
[0060] Specifically, in the elastic wave device of the fourth embodiment described above, by adjusting the duty cycle of the electrode fingers between two adjacent transverse virtual electrode fingers 231, the sound speed in this region is higher than the sound speed in the interlaced region S.
[0061] In some of these embodiments, the length and width of the lateral virtual electrode fingers 231 on the extended electrode fingers 230 are different.
[0062] Specifically, Figure 10 This is a schematic diagram of the structure of the elastic wave device according to the fifth embodiment of this application, as shown below. Figure 10 As shown, the length and width of the transverse virtual electrode finger 231 on the extended electrode finger 230 are different. According to the first embodiment above, the region of the transverse virtual electrode finger 231 is a low sound speed region. By adjusting the length and width of the transverse virtual electrode finger 231 respectively, the frequency response and parasitic response of the sound wave in this region can be accurately controlled, thereby improving the transmission efficiency of the sound wave of the target mode of the elastic wave device.
[0063] In some of these embodiments, the lateral virtual electrode finger 231 is connected to only one adjacent electrode finger.
[0064] Specifically, Figure 11 This is a schematic diagram of the structure of the elastic wave device according to the sixth embodiment of this application, as shown below. Figure 11 As shown, the lateral virtual electrode finger 231 is connected to only one adjacent electrode finger. This structure can further reduce the sound speed in the low-sound speed region L2, thereby increasing the sound speed difference between the staggered region S and the low-sound speed region L2, and better lateral energy leakage in the Y direction.
[0065] like Figure 11 As shown, the transverse virtual electrode finger 231 has protrusions on both the connected electrode finger and the longitudinal virtual electrode finger 232 to further reduce the sound speed in the low-sound speed region L2, thereby increasing the sound speed difference between the interlaced region S and the low-sound speed region L2.
[0066] The elastic wave device of this application will now be described through preferred embodiments and comparative examples.
[0067] Preferred embodiment
[0068] Figure 12 This is a schematic diagram of the structure of the elastic traveling wave device according to this preferred embodiment. Figure 13 The structural schematic diagram of the elastic wave device for comparison is shown in Table 1. The structural parameters are as follows:
[0069] Table 1:
[0070] Structural parameters Preferred embodiment Comparative example S area duty cycle 0.5 0.5 H2 area duty cycle 0.4 0.5 L2 area duty cycle 0.65 0.5 H1 area duty cycle 0.4 0.5
[0071] Apart from the structural parameters mentioned above, the thickness of the IDT electrode of the elastic wave device in the preferred embodiment and the comparative example is 0.09λ, the length of the staggered region S in the first direction is 15λ, the length of the H2 region in the first direction is 0.2λ, the cutting angle of the piezoelectric substrate 100 is 42° in the Y direction and the X direction is cut, and the wavelength λ of the excited acoustic wave is 2μm.
[0072] Figure 14 This is a sound velocity distribution diagram of the elastic wave device in the preferred embodiment and the comparative example, where the red solid line represents the sound velocity distribution of the elastic wave device in the preferred embodiment; the blue solid line represents the sound velocity distribution of the elastic wave device in the comparative example; in the interlaced regions S and L1, the sound velocities of the elastic wave devices in the preferred embodiment and the comparative example are the same. Figure 14 As shown, the sound speed difference between the high-speed regions H1 and H2 and the interlaced region S in the preferred embodiment is greater than the sound speed difference between the H1 and H2 regions and the interlaced region S in the comparative example; the sound speed difference in the low-speed region L2 in the preferred embodiment is greater than the sound speed difference in the L2 region in the comparative example.
[0073] Figure 15 The diagrams show the admittance-frequency characteristics of the elastic wave devices in the preferred embodiment and the comparative example. The red solid line represents the admittance characteristic curve of the preferred embodiment, and the blue solid line represents the admittance characteristic curve of the comparative example. Figure 15 As shown, the preferred embodiment of the elastic wave device has a passband of 1960MHz to 2025MHz. Figure 16 The above are Q-frequency response diagrams of the elastic wave devices in the preferred embodiment and comparative example, where the red solid line represents the Q-frequency response curve of the preferred embodiment and the blue solid line represents the Q-frequency response curve of the comparative example. Figure 15 and Figure 16 It can be seen that the Q value of the passband of the elastic wave device in this preferred embodiment is higher than the Q value of the passband of the elastic wave device in the comparative example.
[0074] In summary, the elastic wave device of this preferred embodiment increases the speed difference between the interleaved region S and the high-speed and low-speed regions by adjusting the duty cycle of the electrode fingers in the high-speed regions H1 and H2 and the duty cycle of the low-speed region L2, thereby suppressing transverse energy leakage in the Y direction, improving the Q value of the elastic wave device, and thus improving the filtering performance of the elastic wave device.
[0075] The expressions and terms used in this utility model are for illustrative purposes only and should not be considered limiting. The use of "comprising," "possessing," "having," "including," and variations thereof as used herein means to include the following items, their equivalents, and additional items.
[0076] The term "embodiment" in this application refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily imply the same embodiment, nor does it imply that it is mutually exclusive with or independent of other embodiments. It will be clearly or implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.
[0077] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications, alterations, and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.
Claims
1. An elastic wave device characterized by, The piezoelectric substrate comprises: IDT electrodes on the main surface of the piezoelectric substrate; wherein the IDT electrodes comprise bus bars, electrode fingers and extended electrode fingers; the bus bars comprise oppositely arranged first bus bars and second bus bars; the electrode fingers comprise first electrode fingers on the first bus bars and second electrode fingers on the second bus bars, and the first electrode fingers and the second electrode fingers are staggered in the staggered region; the length direction of the electrode fingers is the first direction, and the length direction of the bus bars is the second direction, and the first direction is perpendicular to the second direction; The extended electrode fingers are located between the electrode fingers; each of the extended electrode fingers comprises a transverse virtual electrode finger and a longitudinal virtual electrode finger, and the transverse virtual electrode finger intersects the longitudinal virtual electrode finger; the longitudinal virtual electrode finger is parallel to the first direction, and the transverse virtual electrode finger is parallel to the second direction; Wherein, in the first direction, the region between the transverse virtual electrode finger and the bus bar, and the region between the transverse virtual electrode finger and the tail end of the electrode finger opposite to it are high sound speed regions, and the duty cycle of the electrode finger in the high sound speed region is different from the duty cycle of the electrode finger in the staggered region, so that the sound speed in the high sound speed region is higher than the sound speed in the staggered region.
2. The elastic wave device according to claim 1, wherein The duty cycle of the longitudinal virtual electrode finger is different from the duty cycle of the electrode finger in the staggered region. The region between the transverse virtual electrode finger and the tail end of the electrode finger opposite to it comprises:
3. The elastic wave device according to claim 1, characterized by, In the first direction, the region between the transverse virtual electrode finger and the tail end of the longitudinal virtual electrode finger intersecting with it, and the region between the longitudinal virtual electrode finger and the tail end of the electrode finger opposite to it. The duty cycles of the electrode fingers in the high sound speed regions are also different.
4. The elastic wave device according to claim 1, characterized by, The staggered region comprises a central region and an edge region, and the duty cycle of the electrode finger in the edge region is greater than the duty cycle of the electrode finger in the central region.
5. The elastic wave device according to claim 1, characterized in that, 6. The elastic wave device according to claim 1, wherein The extended electrode finger has at least two transverse virtual electrode fingers. The high sound speed region further comprises the region between two adjacent transverse virtual electrode fingers.
7. The elastic wave device according to claim 6, characterized in that, The length and width of the transverse virtual electrode finger on the extended electrode finger are different.
8. The elastic wave device according to claim 6, characterized in that, The transverse virtual electrode finger is connected to only one adjacent electrode finger.
9. The elastic wave device according to claim 1, characterized in that, In the second direction, the transverse virtual electrode finger has a protrusion on both the electrode finger connected thereto and the longitudinal virtual electrode finger.
10. The elastic wave device of claim 9, wherein,