Acoustic wave device and method for manufacturing same
By employing a series transducer structure and a shared electrode floating design in the surface acoustic wave device, combined with a pseudo-electrode, the energy leakage problem was solved, the quality factor of acoustic wave transmission was improved, and the performance of the acoustic wave device was enhanced.
Patent Information
- Application Number
- CN202411399160.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-09-02
- Filing Date
- 2024-10-09
- Publication Date
- 2026-03-10
AI Technical Summary
Existing surface acoustic wave devices suffer from energy leakage, which leads to a decrease in the quality factor.
The first and second transducers are connected in series and formed by floating them together with a common electrode. The pseudo-electrode is used to reduce acoustic signal leakage and improve the quality factor of the acoustic device.
It effectively reduces noise interference, improves the quality of sound wave transmission, and enhances the performance of the sound wave device.
Smart Images
Figure CN121643683A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to acoustic devices, and more particularly to a surface acoustic wave device for reducing noise. Background Technology
[0002] Surface acoustic wave (SAW) devices can be used for the conversion and transmission of electrical and acoustic signals. SAW devices have numerous applications. For example, SAW filters are used to filter out noise and retain wireless signals in specific frequency bands. They are characterized by low transmission loss, good electromagnetic interference resistance, and small size, and are therefore widely used in various communication products. However, existing SAW filters suffer from energy leakage, resulting in a decrease in the quality factor. In addition, SAW devices can also be used as resonators. Summary of the Invention
[0003] This invention provides an acoustic wave device comprising a piezoelectric substrate and a series transducer assembly. The piezoelectric substrate has a surface, and the series transducer assembly includes a first transducer and a second transducer connected in series and disposed on the surface of the piezoelectric substrate. The first transducer includes a first electrode and a common electrode, and the second transducer includes a second electrode and a common electrode. The common electrode is floating, and the first and second transducers are connected in series via the common electrode.
[0004] This invention also provides a method for manufacturing an acoustic wave device. The method includes providing a piezoelectric substrate having a surface; forming a conductive layer on the surface; and patterning the conductive layer to form a patterned conductive layer. The patterned conductive layer includes a first electrode, a second electrode, and a common electrode with floating potential. The first electrode and the common electrode form a first transducer, and the second electrode and the common electrode form a second transducer. The first transducer and the second transducer are connected in series with respect to the common electrode. Attached Figure Description
[0005] Figure 1 This is a top view of one of the acoustic wave devices in an embodiment of the present invention.
[0006] Figure 2 This is a top view of an acoustic device according to another embodiment of the present invention.
[0007] Figure 3 This is a top view of an acoustic device according to another embodiment of the present invention.
[0008] Figure 4 This is a top view of an acoustic device according to another embodiment of the present invention.
[0009] Figure 5 This is a top view of an acoustic device according to another embodiment of the present invention.
[0010] Figure 6 This is a flowchart illustrating a method for manufacturing an acoustic device according to an embodiment of the present invention.
[0011] Symbol explanation:
[0012] 1,2,3,4: Acoustic wave device
[0013] 10,20:Substrate
[0014] 131, 132, 131a, 132a: Electrodes
[0015] 141, 141a, 142, 142a, 143, 143a: Common electrode
[0016] 151, 152, 151a, 152a: Pseudo-electrodes
[0017] 121, 122: Busbars
[0018] e11, e21, e12, e22: Side
[0019] A1, A2, B1, B2: Overlapping areas
[0020] C1, C2, C3, C4: Overlapping regions
[0021] A: Center point
[0022] IDT1, IDT2, IDT3, IDT4, IDT5, IDT6, IDT7, IDT8: Transducers
[0023] e411, e412, e421, e422: Edges (first end, second end)
[0024] G,Ga,GD1,GD2: Gap
[0025] D1, D2: Direction
[0026] 600: Method
[0027] S602, S604, S606: Steps Detailed Implementation
[0028] Figure 1This is a top view of an acoustic wave device 1 according to one embodiment of the present invention. In some embodiments, the acoustic wave device 1 may be a surface acoustic wave (SAW) filter. For example, the acoustic wave device 1 can convert a radio frequency signal from an antenna into a sound wave, process the sound wave to generate a filtered signal, and output the filtered signal. The radio frequency signal and the filtered signal are electrical signals. The use of the acoustic wave device 1 is only illustrated herein, but the present invention is not limited thereto, and in other embodiments, the acoustic wave device 1 may also be used for other purposes.
[0029] In some embodiments, the acoustic device 1 may include a piezoelectric substrate 10 and a series transducer group disposed on the surface of the piezoelectric substrate 10. The transducer group may include a plurality of interdigital transducers (IDTs). In this embodiment, the transducer group may include transducers IDT1 and IDT2, but the invention is not limited thereto. In some embodiments, the transducer group may include a positive even array of transducers. The piezoelectric substrate 10 may include a substrate and a piezoelectric material layer disposed on the substrate. For example, the substrate of the piezoelectric substrate 10 may include a silicon substrate. The piezoelectric material layer may include piezoelectric single crystals, piezoelectric polycrystalline materials (piezoelectric ceramics), piezoelectric polymers, and piezoelectric composite materials. For example, the piezoelectric material layer may include zinc oxide (ZnO), aluminum nitride (AlN), and lithium tantalate (LiTaO3). The transducer assembly may contain metallic materials, which may include any combination of molybdenum (Mo), copper (Cu), aluminum (Al), gold (Au), platinum (Pt), and tungsten (W).
[0030] In some embodiments, a series transducer assembly may be disposed on a first surface of the piezoelectric substrate 10 and may include a bus bar 121, electrodes 131 and 132, a common electrode 141, and the bus bar 122. Figure 1As shown, busbar 121 and busbar 122 can extend along direction D1. In some embodiments, busbar 121 has a side e11 parallel to direction D1, and busbar 122 has a side e21 parallel to direction D1. Electrode 131 can contact the side e11 of busbar 121, and electrode 131 extends along direction D2 from the side e11 of busbar 121. Electrode 132 can contact the side e21 of busbar 122, and electrode 132 extends along direction D2 from the side e21 of busbar 122. Electrodes 131 and 132 can be aligned along direction D2 to form a straight line. Electrodes 131 and 132 do not contact each other and form a notch G along direction D2. Common electrode 141 is floating. The common electrode 141 has a first end e411 and a second end e412. The distance between the first end e411 of the common electrode 141 and the side e11 of the bus 121 and the distance between the second end e412 of the common electrode 141 and the side e21 of the bus 122 can be the same.
[0031] Transducer IDT1 may include electrode 131 and a common electrode 141, and transducer IDT2 may include electrode 132 and a common electrode 141, thereby connecting transducers IDT1 and IDT2 in series via the common electrode 141. Electrode 131 and the common electrode 141 may have an overlapping region A1 along the projection of direction D1, and electrode 132 and the common electrode 141 may have an overlapping region A2 along the projection of direction D1. Sound waves can be transmitted in the overlapping regions A1 and A2. In one embodiment, the overlapping regions A1 and A2 have the same length along direction D2; for example, the lengths of overlapping regions A1 and A2 are the lengths along direction D2. The common electrode 141 is spaced apart from electrodes 131 and 132 in direction D1. Electrodes 131, 132, and the common electrode 141 may be parallel to direction D2, and generatrix 121 may be parallel to generatrix 122. In the above embodiments, direction D2 may be perpendicular to direction D1, and both direction D1 and direction D2 are parallel to the first surface of the piezoelectric substrate 10. In one embodiment, a non-90-degree angle may be formed between direction D2 and direction D1.
[0032] The cascaded transducer assembly may further include dummy electrodes 151 and 152. Dummy electrode 151 extends from side e11 along direction D2, and dummy electrode 152 extends from side e21 along direction D2. Dummy electrodes 151 and 152 are aligned with the common electrode 141 along direction D2 to form a straight line. Dummy electrodes 151 and 152 are spaced apart from the common electrode 141. By providing dummy electrodes 151 and 152, the leakage of acoustic signals along direction D2 can be further reduced, thereby improving the quality factor of the acoustic device 1. Busbar 121, electrodes 131 and 132, common electrode 141, busbar 122, and dummy electrodes 151 and 152 may be made of the same or different metallic materials.
[0033] In summary, the input electrical signal enters from bus 121, reaches electrode 131, and is converted into an acoustic signal in the overlapping region A1, then transmitted to the common electrode 141. Next, the common electrode 141 converts the electrical signal back into an acoustic signal in the overlapping region A2, and transmits it to electrode 132. Electrode 132 then converts the acoustic signal back into an electrical signal and finally transmits it to bus 122, completing signal filtering and transmission. During acoustic wave propagation, some undesirable phenomena may occur. When the acoustic wave propagates from electrode 131 to the common electrode 141 at transducer IDT1, various directional noise may be generated. Similarly, when the acoustic wave propagates from the common electrode 141 to electrode 132 at transducer IDT2, corresponding directional noise will also be generated. However, due to the symmetrical structure of the series-connected transducer group, the interference from transducers and their noise can be effectively eliminated, resulting in better performance compared to using only a single transducer. The acoustic device 1 effectively improves the quality of acoustic wave transmission and reduces the influence of noise by utilizing the series structure and symmetry of transducers IDT1 and IDT2, thereby enhancing its performance.
[0034] Figure 2 This is a top view of an acoustic device 2 according to another embodiment of the present invention. In some embodiments, the acoustic device 2 may be a surface acoustic wave (SAW) filter. For example, the acoustic device 2 can convert a radio frequency signal from an antenna into a sound wave, process the sound wave to generate a filtered signal, and output the filtered signal. The radio frequency signal and the filtered signal are electrical signals. The use of the acoustic device 2 is only illustrated herein, but the present invention is not limited thereto, and the acoustic device 2 may be used for other purposes in other embodiments.
[0035] In some embodiments, the acoustic device 2 may include a piezoelectric substrate 20 and a transducer array disposed on the surface of the piezoelectric substrate 20. The transducer array may include a plurality of interdigital transducers (IDTs). In this embodiment, the transducer array may include transducers IDT1, IDT2, IDT3, and IDT4, but the invention is not limited thereto. In some embodiments, the transducer array may include any two arrays of transducers. The piezoelectric substrate 20 may include a substrate and a piezoelectric material layer disposed on the substrate. For example, the substrate of the piezoelectric substrate 20 may include a silicon substrate. The piezoelectric material layer may include piezoelectric single crystals, piezoelectric polycrystalline materials (piezoelectric ceramics), piezoelectric polymers, and piezoelectric composite materials. For example, the piezoelectric material layer may include zinc oxide (ZnO), aluminum nitride (AlN), and lithium tantalate (LiTaO3). The transducer may contain metallic materials, which may include any combination of molybdenum (Mo), copper (Cu), aluminum (Al), gold (Au), platinum (Pt) and tungsten (W).
[0036] In some embodiments, the transducer assembly may be disposed on a first surface of the piezoelectric substrate 20 and may include a bus bar 121, electrodes 131, 132, 131a and 132a, common electrodes 141 and 141a, and bus bar 122. Figure 2 As shown, busbar 121 and busbar 122 can extend along direction D1. In some embodiments, busbar 121 has a side e11 parallel to direction D1, and busbar 122 has a side e21 parallel to direction D1. Electrode 131 can contact the side e11 of busbar 121, and electrode 131 extends along direction D2 from the side e11 of busbar 121. Electrode 132 can contact the side e21 of busbar 122, and electrode 132 extends along direction D2 from the side e21 of busbar 122. Electrodes 131 and 132 can be aligned along direction D2. Electrodes 131 and 132 do not contact each other and form a notch G along direction D2. Electrode 131a can contact the side e11 of busbar 121, and electrode 131a extends along direction D2 from the side e11 of busbar 121. Electrode 132a can contact the side e21 of busbar 122, and electrode 132a extends from the side e21 of busbar 122 along direction D2. Electrodes 131a and 132a can be aligned along direction D2. Electrodes 131a and 132a do not contact each other and form a notch Ga along direction D2.
[0037] Two common electrodes 141 and 141a are floating at potentials. Common electrode 141 and electrode 131 form an overlapping region A1, and common electrode 141 and electrode 132 form an overlapping region A2. Sound waves can propagate within overlapping regions A1 and A2. As described above, transducers IDT1 and IDT2 can be connected in series via common electrode 141. Common electrode 141a and electrode 131a form an overlapping region B1, and common electrode 141a and electrode 132a form an overlapping region B2. Sound waves can propagate within overlapping regions B1 and B2. Electrode 131a and common electrode 141a form transducer IDT3, and electrode 132a and common electrode 141a form transducer IDT4, thus transducers IDT3 and IDT4 are connected in series via common electrode 141a. In one embodiment, the common electrode 141 does not contact the common electrode 141a, but the common electrode 141 and the common electrode 141a have the same geometry as the surrounding electrodes, therefore the potential of the common electrode 141 is the same as the potential of the common electrode 141a. In one embodiment, the overlapping region A1 formed by the electrode 131 and the overlapping region A2 formed by the electrode 132 along direction D1 may have the same length. For example, the lengths of the overlapping regions A1 and A2 are along direction D2, and the overlapping region B1 formed by the electrode 131a and the overlapping region B2 formed by the electrode 132a have the same length. Electrode 141 is spaced apart from electrodes 131 and 132 in direction D1, and electrode 141a is spaced apart from electrodes 131a and 132a in direction D1. Electrodes 131, 132, and 141 may be parallel to direction D2, and generatrix 121 may be parallel to generatrix 122. Electrodes 131a, 132a, and 141a may be parallel to direction D2. In the above embodiments, direction D2 may be perpendicular to direction D1, and both direction D1 and direction D2 are parallel to the first surface of the piezoelectric substrate 10. In another embodiment, a non-90-degree angle may be formed between direction D2 and direction D1.
[0038] In one embodiment, a transducer may include multiple electrodes and multiple common electrodes. In some embodiments, common electrodes and electrodes may be added arbitrarily parallel to electrodes 131, 131a, 132, and 132a to form a series transducer group. Figure 2 The two sets of series-connected transducers shown are merely an example; the invention is not limited to this, and N sets of transducers can be connected in parallel. N is a positive integer. For example, in Figure 2In this transducer, IDT1 and IDT3, which are adjacent along direction D1, can each include two electrodes 131 and 131a and two shared electrodes 141 and 141a to form transducer IDT11. Since, under the same electrical structure, acoustic waves are still transmitted between electrodes 131 and the shared electrodes 141a and converted into electrical signals, the electrodes 131 and 131a and the two shared electrodes 141 and 141a of transducer IDT11 can have an overlapping region C1 along the projection of direction D1. In other words, electrodes 132 and 132a and the two shared electrodes 141 and 141a form transducer IDT12, and the electrodes 132 and 132a and the two shared electrodes 141 and 141a of transducer IDT12 can have an overlapping region C2 along the projection of direction D1. Furthermore, transducers IDT11 and IDT12 are connected in series.
[0039] In some embodiments, the cascaded transducer group may include dummy electrodes 151a and 152a, with dummy electrode 151a extending from side e11 along direction D2 and dummy electrode 152a extending from side e21 along direction D2. Dummy electrodes 151a and 152a are aligned with the common electrode 141a along direction D2 to form a straight line. Dummy electrodes 151a, 152a, and the common electrode 141a are spaced apart. By providing dummy electrodes 151a and 152a, leakage of the acoustic signal along direction D2 can be further reduced, thereby improving the quality factor of the acoustic device 2. Busbar 121, electrodes 131, 132, 131a and 132a, common electrodes 141 and 141a, busbar 122, and dummy electrodes 151, 151a, 152, and 152a may be made of the same or different metallic materials.
[0040] In summary, the input electrical signal enters from bus 121, passes through electrodes 131 and 131a, and is converted into an acoustic signal in overlapping regions A1 and B1, then transmitted to common electrodes 141 and 141a. Next, common electrodes 141 and 141a convert the electrical signal back into an acoustic signal in overlapping regions A2 and B2, and transmit it to electrodes 132 and 132a. Finally, electrodes 132 and 132a transmit the electrical signal back to bus 122, completing signal filtering and transmission.
[0041] Figure 3 This is a top view of an acoustic device 3 according to another embodiment of the present invention. The difference between acoustic device 3 and acoustic device 2 is that the number of acoustic transducers can be a positive even number. Figure 3 In this configuration, transducers IDT1, IDT2, IDT5, and IDT6 form a series transducer group, and transducers IDT3, IDT4, IDT7, and IDT8 also form a series transducer group. The number of transducers in the series transducer group can be a positive even number, or 6, 8, etc., and is not limited to this configuration. Figure 3The system consists of four groups. Pseudo-electrodes 151 and 152 are aligned with multiple shared electrodes 141 and 143 along direction D2 to form a straight line. Electrodes 131 and 132 are aligned with one or more shared electrodes 142 along direction D2 to form a straight line. Pseudo-electrodes 151a and 152a are aligned with multiple shared electrodes 141a and 143a along direction D2 to form a straight line. Electrodes 131a and 132a are aligned with one or more shared electrodes 142a along direction D2 to form a straight line. The transducers IDT1, IDT2, IDT3, IDT4, IDT5, IDT6, IDT7, and IDT8 formed by this architecture, as shown by the dashed lines in the figure, can effectively filter and reduce surge effects in the frequency response.
[0042] Figure 3 The transducer shown may include multiple electrodes and multiple common electrodes. In one embodiment, transducers IDT1 and IDT3 adjacent along direction D1 can form transducer IDT11. Since acoustic waves are still transmitted and converted into electrical signals between electrode 131 and common electrode 141a under the same electrical structure, transducers IDT2 and IDT4 adjacent along direction D1 can form transducer IDT12, transducers IDT5 and IDT7 adjacent along direction D1 can form transducer IDT13, and transducers IDT6 and IDT8 adjacent along direction D1 can form transducer IDT14. In other words, the electrodes 131, 131a and the two shared electrodes 141, 141a of transducer IDT11 can have an overlapping region C1 along the projection of direction D1; the two shared electrodes 141, 141a, 142, 142a of transducer IDT12 can have an overlapping region C2 along the projection of direction D1; the two shared electrodes 143, 143a, 142, 142a of transducer IDT13 can have an overlapping region C3 along the projection of direction D1; and the electrodes 132, 132a and the two shared electrodes 143, 143a of transducer IDT14 can have an overlapping region C4 along the projection of direction D1. Furthermore, transducers IDT11, IDT12, IDT13 and IDT14 are connected in series sequentially.
[0043] Figure 4This is a top view of an acoustic device 4 according to another embodiment of the present invention. Busbar 121 has sides e11 and e12, both extending along direction D1. Busbar 122 has sides e21 and e22, both extending along direction D1. Common electrode 141a has a first end e421 and a second end e422. The distance between the first end e421 of common electrode 141a and side e12 of busbar 121 and the distance between the second end e422 of common electrode 141a and side e22 of busbar 122 may be the same. However, in some embodiments, the extension lines of side e11 and side e12 may not be collinear, and the extension lines of side e21 and side e22 may also not be collinear. The distance between the first end e411 of the common electrode 141 and the side e12 of the busbar 121 is greater than the distance between the first end e421 of the common electrode 141a and the side e11 of the busbar 121. The extension line of the busbar 121 is not parallel to direction D2. The distance between the second end e412 of the common electrode 141 and the side e22 of the busbar 122 is less than the distance between the second end e422 of the common electrode 141a and the side e21 of the busbar 122. The extension line of the busbar 122 is not parallel to direction D2. The series transducer group may further include dummy electrodes 151a and dummy electrodes 152a. The dummy electrode 151a contacts the side e12 of the busbar 121 and extends from the side e12 of the busbar 121 along direction D2. The dummy electrode 152a contacts the side e22 of the busbar 122, and extends along direction D2 from the side e22 of the busbar 122. The dummy electrode 151a, the common electrode 141a, and the dummy electrode 152a are aligned along direction D2. The lengths of the dummy electrodes 151, 152, 151a, and 152a may be the same along direction D2. In some embodiments, the distance between the center point A of the common electrode 141 and the side e12 of the busbar 121 is not equal to the distance between the center point of the common electrode 141 and the side e11 of the busbar 121. Transducers IDT5 and IDT6 can be described with reference to the above description, and will not be repeated here.
[0044] Figure 4The transducers shown can include multiple electrodes and multiple shared electrodes. In one embodiment, transducers IDT1, IDT3, and IDT5 adjacent along direction D1 can form transducer IDT11. Since they have the same electrical structure, transducers IDT2, IDT14, and IDT6 adjacent along direction D1 can form transducer IDT12, and transducers IDT11 and IDT12 are connected in series. The number of transducers can be a positive even number, for example, but not limited to 6, 8, etc., transducers connected in series sequentially. The transducers IDT1, IDT2, IDT3, IDT4, IDT5, and IDT6 formed by this architecture, as shown by the dashed lines in the figure, can effectively filter and reduce surge effects in the frequency response.
[0045] Figure 5 This is a top view of an acoustic device 5 according to another embodiment of the present invention. A gap GD1 is formed between the dummy electrode 151 and the common electrode 141, and a gap GD2 is formed between the dummy electrode 152 and the common electrode 141. An electrode gap G is formed between electrodes 131 and 132. In some embodiments, the distance between electrode gap G and gap GD1 is greater than the distance between electrode gap G and gap GD2. Extending this structure, busbars 121 and 122 are parallel to each other, but not parallel to direction D1. The resulting transducer groups IDT1, IDT2, IDT3, and IDT4 can be shown by the dashed lines in the figure, and the number of transducers in this structure can be a positive even number. The effective transducer region formed by this architecture is shown by the dashed lines in the figure, which can effectively filter and reduce surge effects in the frequency response. In one embodiment, the edge of the notch G is not necessarily a right angle, but can also be an acute angle. For example, the edge of electrode 131 near electrode 132 and the edge of electrode 132 near electrode 132 do not contact each other, and the two edges form the notch G along a direction that is not parallel to direction D2. Therefore, the notch G forms an acute angle.
[0046] Figure 5 The transducer shown may include multiple electrodes and multiple common electrodes. In one embodiment, multiple transducers such as IDT1, IDT3, etc., adjacent along direction D1 can form transducer IDT11. Since they have the same electrical structure, multiple transducers such as IDT2, IDT14, etc., adjacent along direction D1 can form transducer IDT12, and transducers IDT11 and IDT12 are connected in series. The number of transducers IDT11 and IDT12 can be a positive integer, for example, but not limited to, 3, 4, 5... transducers connected in parallel.
[0047] Figure 6This is a flowchart of a method 600 for manufacturing an acoustic device according to an embodiment of the present invention. The method includes the following steps: Step S602: providing a piezoelectric substrate having a first surface; Step S604: forming a conductive layer on the first surface; and Step S606: patterning the conductive layer to form a patterned conductive layer.
[0048] In step S602, a piezoelectric substrate is provided, the piezoelectric substrate having a surface. In step S604, a conductive layer is formed on the surface. In step S606, the conductive layer is patterned to form a patterned conductive layer. The patterned conductive layer includes an electrode 131, an electrode 132, a common electrode 141 with floating potential, a dummy electrode 151, and a dummy electrode 152. Electrode 131 and the common electrode 141 form transducer IDT1, and electrode 132 and the common electrode 141 form transducer IDT2. Transducers IDT1 and IDT2 are connected in series via the common electrode 141. Dummy electrode 151 contacts the side e11 of bus 121 and extends along direction D2 from the side e11 of bus 121. Dummy electrode 152 contacts the side e21 of bus 122 and extends along direction D2 from the side e21 of bus 122. The dummy electrode 151, common electrode 141, and dummy electrode 152 are aligned along direction D2. The distance between the first end e411 of the common electrode 141 and the side e11 of the busbar 121 is the same as the distance between the second end e412 of the common electrode 141 and the side e21 of the busbar 122. In one embodiment, in step S606, the conductive layer is patterned to form a patterned conductive layer corresponding to Figures 1-5.
[0049] The present invention provides an acoustic device for use as a filter, wherein two transducers connected in series can reduce clutter effects, and a further even number of parallel transducers extending the structure can further reduce clutter effects.
[0050] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention shall be within the scope of the present invention.
Claims
1. A surface acoustic wave device, comprising: a piezoelectric substrate having a first surface; and a series transducer group comprising a first transducer and a second transducer in series, disposed on the first surface of the piezoelectric substrate, wherein: the first transducer comprises a first electrode and a common electrode; and the second transducer comprises a second electrode and the common electrode; wherein the common electrode is floating, and the first transducer and the second transducer are in series with the common electrode. 2.The surface acoustic wave device of claim 1, wherein: a projection of the first electrode and the common electrode along a first direction has a first overlap region; and a projection of the second electrode and the common electrode along the first direction has a second overlap region.
3. The acoustic wave device according to claim 2, wherein a length of the first overlap region and a length of the second overlap region along a second direction are the same.
4. The acoustic wave device according to claim 1, wherein the series transducer group further comprises: a first bus line extending along a first direction, having a first side parallel to the first direction; and a second bus line extending along the first direction, having a second side parallel to the first direction.
5. The acoustic wave device according to claim 4, wherein the common electrode has a first end and a second end, a distance between the first end of the common electrode and the first side of the first bus line and a distance between the second end of the common electrode and the second side of the second bus line are the same.
6. The acoustic wave device according to claim 4, wherein the series transducer group further comprises: a first dummy electrode contacting the first side of the first bus line and extending along a second direction from the first side of the first bus line; and a second dummy electrode contacting the second side of the second bus line and extending along the second direction from the second side of the second bus line; wherein the first dummy electrode, the common electrode and the second dummy electrode are aligned along the second direction.
7. The acoustic wave device according to claim 4, wherein the first electrode and the second electrode are aligned along a second direction.
8. The acoustic wave device according to claim 4, wherein a gap is disposed between the first electrode and the second electrode along the second direction. 9.The surface acoustic wave device of claim 4, wherein: the first electrode contacts the first side of the first bus line and extends along a second direction from the first side of the first bus line; and the second electrode contacts the second side of the second bus line and extends along the second direction from the second side of the second bus line.
10. The acoustic wave device according to claim 4, wherein the series transducer group further comprises another first electrode, another second electrode and another common electrode, and the another common electrode is floating; wherein the another first electrode and the another common electrode form a third transducer, and the another second electrode and the another common electrode form a fourth transducer, the third transducer and the fourth transducer are in series with the another common electrode. 11.The surface acoustic wave device of claim 10, wherein: the first bus line has a third side parallel to the first direction; the second bus line has a fourth side parallel to the first direction; the another common electrode has a first end and a second end; and the another first electrode and the another common electrode form a third transducer, and the another second electrode and the another common electrode form a fourth transducer, the third transducer and the fourth transducer are in series with the another common electrode. A distance between the first end of the other common electrode to the third side of the first bus line is the same as a distance between the second end of the other common electrode to the fourth side of the second bus line.
12. The acoustic wave device of claim 11, wherein, A distance between the first end of the common electrode to the third side of the first bus line is greater than a distance between the first end of the other common electrode to the first side of the first bus line.
13. The acoustic wave device of claim 11, wherein: An extension line of the first side is not collinear with an extension line of the third side.
14. The acoustic wave device of claim 11, wherein, The series-connected transducer group further comprises: a third dummy electrode contacting the third side of the first bus line and extending in a second direction from the first side of the first bus line; and a fourth dummy electrode contacting the fourth side of the second bus line and extending in the second direction from the second side of the second bus line; wherein the third dummy electrode, the other common electrode, and the fourth dummy electrode are aligned in the second direction; wherein lengths of the first dummy electrode, the second dummy electrode, the third dummy electrode, and the fourth dummy electrode are the same in the second direction.
15. The acoustic wave device of claim 11, wherein: A distance between a center point of the common electrode to the third side of the first bus line is not equal to the distance between the center point of the common electrode to the first side of the first bus line.
16. The acoustic wave device of claim 15, wherein: there is an electrode gap between the first electrode and the second electrode; there is a first gap between the first dummy electrode and the common electrode; and there is a second gap between the second dummy electrode and the common electrode; wherein a distance of the electrode gap and the first gap is greater than a distance of the electrode gap and the second gap.
17. The acoustic wave device of claim 10, wherein, A number of the series-connected transducer group is a positive even number.
18. The acoustic wave device of claim 10, wherein, The common electrode is not coupled to the other common electrode.
19. A method of manufacturing an acoustic wave device, comprising: providing a piezoelectric substrate having a first surface; forming a conductive layer on the first surface; and patterning the conductive layer to form a patterned conductive layer comprising: a first transducer comprising a first electrode and a common electrode; and a second transducer comprising a second electrode and the common electrode; wherein the common electrode is electrically floating, and the first transducer and the second transducer are connected in series with the common electrode.
20. The method of manufacturing an acoustic wave device according to claim 19, wherein The patterned conductive layer further comprises: a first bus line extending in a first direction having a first side parallel to the first direction; and a second bus line extending in the first direction having a second side parallel to the first direction; wherein the common electrode has a first end and a second end; and A distance between the first end of the common electrode and the first side of the first bus bar and a distance between the second end of the common electrode and the second side of the second bus bar are the same.
21. The method for manufacturing an acoustic wave device according to claim 20, wherein The patterned conductive layer further comprises: a first dummy electrode contacting the first side of the first bus bar and extending from the first side of the first bus bar in a second direction; and a second dummy electrode contacting the second side of the second bus bar and extending from the second side of the second bus bar in the second direction; wherein the first dummy electrode, the common electrode, and the second dummy electrode are aligned in the second direction.