Electroacoustic transducer, surface acoustic wave resonator and surface acoustic wave device

Abstract

The invention relates to an electroacoustic transducer, a surface acoustic wave resonator and a surface acoustic wave device, and belongs to the technical field of radio frequency filtering, and the surface acoustic wave resonator comprises a piezoelectric substrate and the electroacoustic transducer arranged on the working surface of the piezoelectric substrate; the electroacoustic transducer is connected with the piezoelectric substrate. According to the invention, a good transverse mode inhibition effect can be realized.

Description

Technical Field

[0001] The present invention application relates to the technical field of radio frequency filtering, and in particular to an electroacoustic transducer, a surface acoustic wave resonator and a surface acoustic wave device. Background Art

[0002] As a frequency source device, a surface acoustic wave device is widely used in communication, remote control, alarm and other systems. The performance of traditional surface acoustic wave devices is often reduced due to spurious waves caused by transverse modes. As Figure 1 shown, the structure of a traditional electroacoustic transducer 100. On both sides of the acoustic wave propagation direction of the electroacoustic transducer 100, a first reflector 15 and a second reflector 16 are arranged. The electroacoustic transducer 100 includes a plurality of electrode fingers one 11 and a plurality of electrode fingers two 12 that are arranged alternately and oppositely. The starting end of the electrode finger one 11 is connected to the bus bar one 13. The end of the electrode finger one 11 is inserted between two adjacent electrode fingers two 12 on the opposite side and does not contact each other. The starting end of the electrode finger two 12 is connected to the bus bar two 14. The end of the electrode finger two 12 is inserted between two adjacent electrode fingers one 11 on the opposite side and does not contact each other. The dummy finger electrode one 19 is connected to the bus bar one 13. The starting end of the dummy finger electrode one 19 is directly connected to the bus bar one 13. The dummy finger electrode one 19 is arranged between the end of the electrode finger two 12 and the bus bar one 13. The dummy finger electrode one 19 and the electrode finger one 11 are arranged alternately; the dummy finger electrode two 18 is connected to the bus bar two 14. The starting end of the dummy finger electrode two 18 is directly connected to the bus bar two 14. The dummy finger electrode two 18 is arranged between the end of the electrode finger one 11 and the bus bar two 14. The dummy finger electrode two 18 and the electrode finger two 12 are arranged alternately. The electrode finger one 11 and the electrode finger two 12 are also collectively referred to as interdigital electrodes. When the surface acoustic wave device adopts the traditional electroacoustic transducer 100, due to the inability to effectively suppress the transverse mode of the surface acoustic wave device, the fluctuation in the passband is large, and thus it cannot be applied to high-performance surface acoustic wave devices. Therefore, it is necessary to technically improve the structure of the traditional electroacoustic transducer 100.

[0003] As Figure 2 shown, the structure of the improved electroacoustic transducer 200. The electroacoustic transducer 200 includes alternately arranged electrode fingers one 21 and electrode fingers two 22. The length of the electrode fingers one 21 in the excitation region gradually decreases from the middle of the region to the end of the region. The length of the electrode fingers two 22 in the excitation region gradually decreases from the middle of the region to the end of the region. The electrode fingers one 21 and the electrode fingers two 22 are also collectively referred to as interdigital electrodes. The electroacoustic transducer 200 does not have dummy finger electrodes. As Figure 3As shown, the measured insertion loss / VSWR-frequency curve of the electroacoustic transducer 200 after being applied to the surface acoustic wave device shows that: the electroacoustic transducer 200 exhibits a better lateral mode suppression level than the traditional electroacoustic transducer 100, and the in-band fluctuations are reduced. However, due to the absence of dummy fingers in the electroacoustic transducer 200, during the actual fabrication process of the surface acoustic wave device (such as a filter or a multiplexer), the interdigital electrodes cannot be peeled off, resulting in an increase in the minimum insertion loss and VSWR, which affects the yield of the surface acoustic wave device and even damages the performance of the surface acoustic wave device. Summary of the Invention

[0004] The present invention provides an electroacoustic transducer, a surface acoustic wave resonator, and a surface acoustic wave device, aiming to partially or fully solve the technical problem that the non-peeling of the interdigital electrodes in the prior art increases the minimum insertion loss (abbreviated as minimum IL) and VSWR, affecting the yield of the surface acoustic wave device (such as a filter or a multiplexer) and even damaging the performance of the surface acoustic wave device (such as a filter or a multiplexer). The present invention controls the distance between the dummy fingers and the interdigital electrodes to achieve a surface acoustic wave device (such as a filter or a multiplexer) with a good transverse mode suppression effect and easy processing and fabrication. To achieve the above object, the present invention adopts the following technical solutions:

[0005] In a first aspect, an electroacoustic transducer includes: a plurality of first electrode fingers and a plurality of second electrode fingers arranged alternately and oppositely along a first direction. The starting ends of the first electrode fingers are connected to a first bus bar, and at least part of the ending ends of the first electrode fingers are inserted between two adjacent second electrode fingers on the opposite side. The starting ends of the second electrode fingers are connected to a second bus bar, and at least part of the ending ends of the second electrode fingers are inserted between two adjacent first electrode fingers on the opposite side. The starting end of a first dummy finger electrode is connected to the first bus bar, and the ending end of the first dummy finger electrode is disposed between the ending end of the second electrode finger and the first bus bar. Along the first direction, the first dummy finger electrode and the first electrode fingers are arranged alternately. The starting end of a second dummy finger electrode is connected to the second bus bar, and the ending end of the second dummy finger electrode is disposed between the ending end of the first electrode finger and the second bus bar. Along the first direction, the second dummy finger electrode and the second electrode fingers are arranged alternately. In a cross region formed by the overlapping portions of the first electrode fingers and the second electrode fingers along the first direction, the cross region includes: a middle region located on the middle side in a second direction; a first low sound velocity region formed on the side of the middle region close to the first bus bar and having a sound velocity lower than that in the middle region; a second low sound velocity region formed on the side of the middle region close to the second bus bar and having a sound velocity lower than that in the middle region. The first low sound velocity region and the second low sound velocity region are formed by providing electrode finger mass addition portions on the first electrode fingers and the second electrode fingers. It is characterized in that the electroacoustic transducer includes a first distance g1 and a second distance g2, satisfying: g1≥2λ, g2≥2λ. The first distance g1 is the distance from the ending end of the first electrode finger to the ending end of the first dummy finger electrode along the second direction, and the second distance g2 is the distance from the ending end of the second electrode finger to the ending end of the second dummy finger along the second direction, where λ is the wavelength of the sound wave.

[0006] Optionally, along the first direction, the width of the electrode finger mass addition portion is greater than the widths of the first dummy finger electrode and the second dummy finger electrode.

[0007] Optionally, along a third direction, the thickness of the electrode finger mass addition portion is greater than the thicknesses of the first dummy finger electrode and the second dummy finger electrode, and the third direction is the height direction of the electroacoustic transducer.

[0008] Optionally, a first reflector and a second reflector are provided on both sides of the sound wave propagation direction of the electroacoustic transducer.

[0009] In a second aspect, a surface acoustic wave resonator is characterized by including: a piezoelectric substrate, and an electroacoustic transducer provided on the working surface of the piezoelectric substrate; the electroacoustic transducer is connected to the piezoelectric substrate, and the electroacoustic transducer is any one of the electroacoustic transducers in the first aspect above.

[0010] In a third aspect, a surface acoustic wave device, the surface acoustic wave device is a filter or a multiplexer, the filter or the multiplexer includes a resonator, and the resonator is the surface acoustic wave resonator in the second aspect above.

[0011] In summary, the present invention application has the following beneficial technical effects:

[0012] (1) In the present invention application, through the settings of the first distance g1 (g1≥2λ) and the second distance g2 (g2≥2λ) of the electroacoustic transducer, the passband of the surface acoustic wave device of the electroacoustic transducer is flatter, the minimum insertion loss and voltage standing wave ratio are smaller, the phenomenon that the interdigital electrodes cannot be peeled off is reduced or avoided, and at the same time, a good transverse mode suppression effect can be achieved;

[0013] (2) In the present invention application, along the first direction, the width of the electrode finger mass addition part is greater than the widths of the first dummy finger electrode and the second dummy finger electrode, and along the third direction, the thickness of the electrode finger mass addition part is greater than the thicknesses of the first dummy finger electrode and the second dummy finger electrode. The geometric width dimension of the electrode finger mass addition part increases, so that a clear acoustic wave velocity boundary is formed between the low acoustic velocity region and the standard acoustic velocity region; the low acoustic velocity region is lower than the standard acoustic velocity region, and the acoustic velocity difference forms a transverse constraint on the acoustic wave, which can concentrate the energy of the acoustic wave in the middle region, making the low acoustic velocity region become the "damping zone" of the acoustic wave, reducing the generation of parasitic modes (such as transverse modes or bulk wave modes) and stray wave signals, reducing the influence on the yield of the surface acoustic wave device, and facilitating the processing and preparation of the surface acoustic wave device (such as filters or multiplexers, etc.), improving the performance stability of the surface acoustic wave device. Description of the Drawings

[0014] Figure 1 is a schematic structural diagram of a traditional electroacoustic transducer 100 in the prior art;

[0015] Figure 2 is a schematic structural diagram of an improved electroacoustic transducer 200 in the prior art;

[0016] Figure 3 is a measured insertion loss / voltage standing wave ratio - frequency curve graph after the electroacoustic transducer 200 in the prior art is applied to a surface acoustic wave device;

[0017] Figure 4 is a schematic structural diagram of an electroacoustic transducer 400 of the present invention application;

[0018] Figure 5 is a measured insertion loss / voltage standing wave ratio - frequency curve graph after the electroacoustic transducer 400 of the present invention application is applied to a surface acoustic wave device;

[0019] Figure 6 is a schematic structural diagram of another electroacoustic transducer 300 of the present invention application;

[0020] Figure 7It is the measured insertion loss / VSWR - frequency curve graph after the electroacoustic transducer 300 of the present invention application is applied to a surface acoustic wave device. Detailed implementation manners

[0021] In the following description, numerous specific details are given to provide a more thorough understanding of the present invention application. However, it is obvious to those skilled in the art that the present invention application can be implemented without one or more of these details. In other examples, some technical features well known to the art are not described to avoid confusion with the present invention application.

[0022] In a first aspect, as Figure 4 shown, the present invention application provides an electroacoustic transducer 400, including: a plurality of first electrode fingers 1 and a plurality of second electrode fingers 2 arranged alternately and oppositely along a first direction. The starting end of the first electrode finger 1 is connected to a first bus bar 3, and at least part of the ending end of the first electrode finger 1 is inserted between two adjacent second electrode fingers 2 on the opposite side; the starting end of the second electrode finger 2 is connected to a second bus bar 4, and at least part of the ending end of the second electrode finger 2 is inserted between two adjacent first electrode fingers 1 on the opposite side; the starting end of the first dummy finger electrode 9 is connected to the first bus bar 3, and the ending end of the first dummy finger electrode 9 is arranged between the ending end of the second electrode finger 2 and the first bus bar 3; along the first direction, the first dummy finger electrode 9 and the first electrode finger 1 are arranged alternately; the starting end of the second dummy finger electrode 8 is connected to the second bus bar 4, and the ending end of the second dummy finger electrode 8 is arranged between the ending end of the first electrode finger 1 and the second bus bar 4. Along the first direction, the second dummy finger electrode 8 and the second electrode finger 2 are arranged alternately; in the cross - region DA formed by the overlapping part of the first electrode finger 1 and the second electrode finger 2 along the first direction, the cross - region DA includes: an intermediate region DB, located on the intermediate side in the second direction y; a first low - sound - velocity region, formed on the side of the intermediate region DB close to the first bus bar 3 and having a sound velocity lower than that in the intermediate region; a second low - sound - velocity region, formed on the side of the intermediate region DB close to the second bus bar 4 and having a sound velocity lower than that in the intermediate region; the first low - sound - velocity region and the second low - sound - velocity region are formed by arranging electrode finger mass addition parts 7 on the first electrode finger 1 and the second electrode finger 2. The electroacoustic transducer 400 includes a first distance g1 and a second distance g2, satisfying: g1≥2λ, g2≥2λ. The first distance g1 is the distance from the ending end of the first electrode finger 1 to the ending end of the first dummy finger 8 along the second direction, and the second distance g2 is the distance from the ending end of the second electrode finger 2 to the ending end of the second dummy finger 9 along the second direction, where λ is the wavelength of the sound wave.

[0023] In some embodiments, the first electrode fingers 1 and the second electrode fingers 2 are also collectively referred to as interdigital electrodes. The first direction can be the arrangement direction of the first electrode fingers 1 or the second electrode fingers 2, the first direction can also be the x-axis direction, and the x-axis direction is also the acoustic wave propagation direction. The second direction can be the extension direction of the first electrode fingers 1 or the second electrode fingers 2, the second direction can also be the y-axis direction, and the third direction can be the height direction of the electroacoustic transducer, and the third direction can also be the z-axis direction. The first direction, the second direction, and the third direction intersect pairwise. Preferably, the first direction, the second direction, and the third direction are perpendicular to each other pairwise, that is, a 90-degree angle is formed between each pair.

[0024] In some embodiments, in the cross-region DA formed by the overlapping portions of the first electrode fingers 1 and the second electrode fingers 2 along the first direction, the cross-region DA includes an intermediate region DB on the intermediate side in the second direction y, a first outer region DC1 formed on the side of the intermediate region DB close to the first bus bar 3, and a second outer region DC2 formed on the side of the intermediate region DB close to the second bus bar 4. In the first outer region DC1, electrode finger mass addition portions 7 are provided on the first electrode fingers 1 and the second electrode fingers 2. By providing the electrode finger mass addition portions 7 on a plurality of the first electrode fingers 1 and a plurality of the second electrode fingers 2, in the first outer region DC1, the sound velocity becomes lower than the sound velocity in the intermediate region DB, and thus a first low sound velocity region with a sound velocity lower than that in the intermediate region DB is formed. Similarly, in the second outer region DC2, by providing the electrode finger mass addition portions 7 on a plurality of the first electrode fingers 1 and a plurality of the second electrode fingers 2, correspondingly, a second low sound velocity region with a sound velocity lower than that in the intermediate region DB is also formed.

[0025] In some embodiments, two spaced-apart electrode finger mass addition portions 7 are provided on the first electrode fingers 1, and two spaced-apart electrode finger mass addition portions 7 are provided on the second electrode fingers 2. The electrode finger mass addition portion 7 can be an electrode mass addition film, and the electrode mass addition film can be made of a metal material, and the metal material can include Pt, etc.

[0026] In some embodiments, the electroacoustic transducer 400 is formed with a first edge region DD1 on the outer side in the second direction y of the first outer region DC1. The first edge region DD1 is located between the first outer region DC1 and the first bus bar 3, and the first edge region DC1 is located between the intermediate region B and the first edge region DD1. Similarly, the electroacoustic transducer 400 is formed with a second edge region DD2 on the outer side in the second direction y of the second outer region DC2. The second edge region DD2 is located between the second outer region DC2 and the second bus bar 4, and the second edge region DC2 is located between the intermediate region DB and the second outer region DD2.

[0027] In some embodiments, in the first edge region DD1, a first electrode finger 1 and a first dummy finger electrode 9 are provided. The end of the first dummy finger electrode 9 is disposed between the end of the second electrode finger 2 and the first bus bar 3. In the second edge region D2, a second electrode finger 2 and a first dummy finger electrode 8 are provided. The end of the second dummy finger electrode 8 is disposed between the end of the first electrode finger 1 and the second bus bar 4. The sound velocity in the first edge region DD1 and the second edge region DD2 becomes higher than the sound velocity in the middle region B.

[0028] In some embodiments, the sound velocity of the sound wave in the middle region DB is set as VB, the sound velocity of the sound wave in the first outer region DC1 and the second outer region DC2 is set as VC, and the sound velocity of the sound wave in the first edge region DD1 and the second edge region DD2 is set as VD, satisfying: VC < VB < VD. Correspondingly, a first low sound velocity region is provided in the first edge region DC1, a second low sound velocity region is provided in the second edge region DC2, a standard sound velocity region is formed in the middle region DB, a first high sound velocity region is provided in the first outer region D1, and a second high sound velocity region is provided in the second outer region D2.

[0029] It should be noted that, as Figure 4 shown, first, the first distance g1 is the distance along the second direction from the end of the first electrode finger 1 (i.e., the end of the electrode finger mass addition part 7 on the first electrode finger 1, at this time the head end of the electrode finger mass addition part 7 on the first electrode finger 1 is connected to the second electrode finger 2) to the end of the first dummy finger electrode 8, and the second distance g2 is the distance along the second direction from the end of the second electrode finger 2 (i.e., the end of the electrode finger mass addition part 7 on the second electrode finger 2, at this time the head end of the electrode finger mass addition part 7 on the second electrode finger 2 is connected to the second electrode finger 2) to the end of the second dummy finger 9. In addition, for the convenience of describing the characteristics of the standard sound velocity region, the first low sound velocity region, the second low sound velocity region, the first high sound velocity region, and the second high sound velocity region, straight line connections are simply used in the formation of the cross region DA, the middle region DB, the first outer region DC1, the second outer region DC2, the first edge region DD1, and the second edge region DD2 to approximately illustrate the standard sound velocity region, the first low sound velocity region, the second low sound velocity region, the first high sound velocity region, and the second high sound velocity region. The specific region composition or size, etc. of the standard sound velocity region, the first low sound velocity region, the second low sound velocity region, the first high sound velocity region, and the second high sound velocity region may also exactly correspond to the standard sound velocity region, the first high sound velocity region, and the second high sound velocity region derived from rigorous theoretical derivation. The present invention application does not make special restrictions on this.

[0030] In some embodiments, in the second direction y, the electroacoustic transducer 400 is sequentially formed with a first high sound velocity region, a first low sound velocity region, a standard sound velocity region, a second low sound velocity region, and a second high sound velocity region. Accordingly, sound waves can propagate at different speeds in different regions, presenting a regular propagation mode similar to piston motion, which can be called the piston mode. Thus, after the electroacoustic transducer 400 is used to form a surface acoustic wave device, the above piston mode can be utilized to effectively suppress the spurious signals caused by the transverse mode.

[0031] As Figure 3 , Figure 7 and Figure 5 shown, in the present invention application, through the settings of the first distance g1 (g1≥2λ) and the second distance g2 (g2≥2λ) of the electroacoustic transducer 400, the passband of the surface acoustic wave device of the electroacoustic transducer 400 is flatter, and the minimum insertion loss is smaller, reducing or avoiding the phenomenon that the interdigital electrodes cannot be peeled off, and reducing the influence on the yield and performance of the surface acoustic wave device.

[0032] Optionally, along the first direction, the width of the electrode finger mass addition part 7 is greater than the widths of the first dummy finger electrode 9 and the second dummy finger electrode 8; and / or, along the third direction, the thickness of the electrode finger mass addition part 7 is greater than the thicknesses of the first dummy finger electrode 9 and the second dummy finger electrode 8, and the third direction is the height direction of the electroacoustic transducer.

[0033] In the present invention application, first, along the first direction, the width of the electrode finger mass addition part 7 is greater than the widths of the first dummy finger electrode 9 and the second dummy finger electrode 8, and along the third direction, the thicknesses of the electrode finger mass addition part 7 are greater than the thicknesses of the first dummy finger electrode 9 and the second dummy finger electrode 8. The geometric width dimension of the electrode finger mass addition part 7 increases, making the low sound velocity region and the standard sound velocity region form a clear sound wave velocity boundary; the low sound velocity region is lower than the standard sound velocity region, and the sound velocity difference forms a lateral constraint on the sound wave, which can concentrate the energy of the sound wave in the middle region, making the low sound velocity region become the "damping zone" of the sound wave, reducing the generation of parasitic modes (such as transverse mode or bulk wave mode) and spurious wave signals, reducing the influence on the yield of the surface acoustic wave device, facilitating the processing and preparation of the surface acoustic wave device (such as filters or multiplexers, etc.), and also improving the performance stability of the surface acoustic wave device.

[0034] In some embodiments, on both sides of the acoustic wave propagation direction of the electroacoustic transducer 400, a first reflector 5 and a second reflector 6 are provided. Both the first reflector 5 and the second reflector 6 include multiple reflector electrode fingers, and a third bus bar and a fourth bus bar that are opposed to each other in the extending direction of the multiple reflector electrode fingers. Each reflector electrode finger has its own first end and second end. The first end of the reflector electrode finger is directly connected to the third bus bar, and the second end of the reflector electrode finger is directly connected to the fourth bus bar. These belong to the prior art in existing surface acoustic wave devices, and the present invention application will not elaborate on this again.

[0035] In a second aspect, a surface acoustic wave resonator includes: a piezoelectric substrate, and an electroacoustic transducer disposed on the working surface of the piezoelectric substrate; the electroacoustic transducer is connected to the piezoelectric substrate, and the electroacoustic transducer is any one of the electroacoustic transducers in the first aspect above.

[0036] In some embodiments, the piezoelectric substrate is a basic part of the surface acoustic wave device. The piezoelectric substrate is usually made of a material with piezoelectric effect. Exemplarily, lithium niobate (LiNbO 3 ), lithium tantalate (LiTaO 3 ), quartz, zinc oxide (ZnO), aluminum nitride (AlN), etc. The function of the piezoelectric substrate is to provide a medium for acoustic wave propagation, and generate mechanical vibration under the action of an electric field. Conversely, it can also convert mechanical vibration into an electrical signal. In the second direction y, an electroacoustic transducer is disposed on the working surface of the piezoelectric substrate; the electroacoustic transducer is connected to the piezoelectric substrate. The piezoelectric substrate belongs to the technology in existing surface acoustic wave devices, and the present invention application will not elaborate on this here again.

[0037] In a third aspect, a surface acoustic wave device, the surface acoustic wave device is a filter or a multiplexer. The filter or multiplexer includes resonators, and the resonators are any one of the surface acoustic wave resonators in the second aspect above.

[0038] In some embodiments, the filter or multiplexer can be used as the surface acoustic wave device of the present invention application. The filter or multiplexer can include resonators, and the resonators can be any one of the surface acoustic wave resonators in the second aspect above.

[0039] (1) Test result terms

[0040] Voltage Standing Wave Ratio (VSWR): The voltage standing wave ratio is an important indicator to measure the flatness of the filter passband. When the voltage standing wave ratio is closer to 1, it indicates that the filter passband is flatter; 3dB bandwidth: The bandwidth is an important indicator to measure the performance of a radio frequency device. Usually, it is the difference between the upper cut-off frequency and the lower cut-off frequency when the insertion loss of the radio frequency device is -3dB.

[0041] (2) Test condition comparison

[0042] Test example: Such asFigure 6 As shown in the figure, an electroacoustic transducer 300 includes: a plurality of first electrode fingers 1 and a plurality of second electrode fingers 2 that are arranged relatively and alternately along a first direction. The starting ends of the first electrode fingers 1 are connected to a first bus bar 3, and at least a part of the ending ends of the first electrode fingers 1 are inserted between two adjacent second electrode fingers 2 on the opposite side. The starting ends of the second electrode fingers 2 are connected to a second bus bar 4, and at least a part of the ending ends of the second electrode fingers 2 are inserted between two adjacent first electrode fingers 1 on the opposite side. The starting end of the first dummy finger electrode 9 is connected to the first bus bar 3, and the ending end of the first dummy finger electrode 9 is arranged between the ending end of the second electrode finger 2 and the first bus bar 3. Along the first direction, the first dummy finger electrode 9 and the first electrode fingers 1 are arranged alternately. The starting end of the second dummy finger electrode 8 is connected to the second bus bar 4, and the ending end of the second dummy finger electrode 8 is arranged between the ending end of the first electrode finger 1 and the second bus bar 4. Along the first direction, the second dummy finger electrode 18 and the second electrode fingers 12 are arranged alternately. The electroacoustic transducer 300 includes a first distance g1 and a second distance g2, satisfying: g1 < 2λ, g2 < 2λ. The first distance g1 is the distance from the ending end of the first electrode finger 1 to the ending end of the first dummy finger electrode 8 along a second direction, and the second distance g2 is the distance from the ending end of the second electrode finger 2 to the ending end of the second dummy finger 9 along the second direction, where λ is the wavelength of the sound wave. Thus, in the test example, the only difference between the electroacoustic transducer 300 (as Figure 5 described) and the electroacoustic transducer 400 in the embodiment of the present invention application (as Figure 4 shown) is that: the first distance g1 and the second distance g2 are less than twice the wavelength of the sound wave, and other test parameters and conditions are the same.

[0043] (3) Comparison of test results

[0044] As Figure 3 shown, the measured insertion loss / standing wave ratio - frequency curve of the surface acoustic wave device of the electroacoustic transducer 200. The surface acoustic wave device has a center frequency of 1225 MHz, a 3 dB bandwidth of 180 MHz,

[0045] a minimum insertion loss of -1.10 dB, an out-of-band rejection greater than 35 dB, and a standing wave ratio less than 1.7. It can be seen from the curve that the standing wave ratio of the surface acoustic wave device exceeds 2, and there is a large jitter in the passband.

[0046] As Figure 7 shown, the measured insertion loss / standing wave ratio - frequency curve of the surface acoustic wave device of the electroacoustic transducer 300. The surface acoustic wave device has a center frequency of 1224 MHz, a 3 dB bandwidth of 174 MHz,

[0047] The minimum insertion loss is -1.35 dB, the out-of-band suppression is greater than 35 dB, and the standing wave ratio is less than 2.5. From the curve, it can be seen that the standing wave ratio of the surface acoustic wave device with the electroacoustic transducer 300 exceeds 2, and the jitter in the passband is large, which is caused by the first distance g1 and the second distance g2 being too small.

[0048] like Figure 5 As shown in FIG. 1 , a measured insertion loss / standing wave ratio-frequency curve of a surface acoustic wave device with an electroacoustic transducer 400 is shown. The surface acoustic wave device has a center frequency of 1225 MHz, a 3 dB bandwidth of 182 MHz, a minimum insertion loss of -1.06 dB, an out-of-band suppression of greater than 35 dB, and a standing wave ratio of less than 1.6. It can be seen from the curve that, compared with the surface acoustic wave device with the electroacoustic transducer 300, the surface acoustic wave device with the electroacoustic transducer 400 has a flatter passband and a smaller insertion loss.

[0049] Therefore, it can be seen that: by setting the first distance g1 (g1≥2λ) and the second distance g2 (g2≥2λ) of the electroacoustic transducer 400, the passband of the surface acoustic wave device of the electroacoustic transducer 400 is flatter, the minimum insertion loss and the standing wave ratio are smaller, and the phenomenon that the interdigital electrodes cannot be peeled off is reduced or avoided, and a good transverse mode suppression effect can be achieved;

[0050] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

[0051] As mentioned above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be interpreted as limiting the present invention itself. Various changes can be made to it in form and detail without departing from the spirit and scope of the present invention defined in the appended claims.

Claims

1. An electroacoustic transducer, comprising: A plurality of first electrode fingers and a plurality of second electrode fingers are arranged relatively staggered along a first direction, the starting end of the first electrode finger is connected to the first bus bar, and at least a part of the first electrode finger end is inserted between two adjacent second electrode fingers on the opposite side; the starting end of the second electrode finger is connected to the second bus bar, and at least a part of the second electrode finger end is inserted between two adjacent first electrode fingers on the opposite side; the starting end of the first pseudo-finger electrode is connected to the first bus bar, and the end of the first pseudo-finger electrode is arranged between the end of the second electrode finger and the first bus bar; along the first direction, the first pseudo-finger electrodes and the first electrode fingers are arranged alternately; the starting end of the second pseudo-finger electrode is connected to the second bus bar, and the end of the second pseudo-finger electrode is arranged between the end of the first electrode finger and the second bus bar; along the first direction, the second pseudo-finger electrodes and the second electrode fingers are arranged alternately; In the intersection area formed by the overlapping parts of the first electrode finger and the second electrode finger along the first direction, the intersection area includes: an intermediate area, located on the intermediate side in the second direction; a first low sound velocity area, formed on the side of the intermediate area close to the first bus bar, and the sound velocity is lower than the sound velocity in the intermediate area; a second low sound velocity area, formed on the side of the intermediate area close to the second bus bar, and the sound velocity is lower than the sound velocity in the intermediate area; the first low sound velocity area and the second low sound velocity area are formed by arranging an electrode finger mass addition portion on the first electrode finger and the second electrode finger; it is characterized in that the electroacoustic transducer includes a first distance g1 and a second distance g2, satisfying: g1≥2λ, g2≥2λ, the first distance g1 is the distance from the end of the first electrode finger to the end of the first dummy finger electrode along the second direction, the second distance g2 is the distance from the end of the second electrode finger to the end of the second dummy finger along the second direction, and λ is the wavelength of the sound wave.

2. The electroacoustic transducer according to claim 1, characterized in that: Along the first direction, the width of the electrode finger mass addition portion is greater than the width of the first dummy finger electrode and the second dummy finger electrode.

3. The electroacoustic transducer according to claim 2, characterized in that: Along the third direction, the thickness of the electrode finger mass addition portion is greater than the thickness of the first dummy finger electrode and the second dummy finger electrode, and the third direction is the height direction of the electroacoustic transducer.

4. The electroacoustic transducer according to claim 2, characterized in that: g1=g2, a first reflector and a second reflector are arranged on both sides of the sound wave propagation direction of the electroacoustic transducer.

5. A surface acoustic wave resonator, characterized in that: include: A piezoelectric substrate, and an electroacoustic transducer arranged on a working surface of the piezoelectric substrate; the electroacoustic transducer is connected to the piezoelectric substrate, and the electroacoustic transducer is the electroacoustic transducer according to any one of claims 1 to 4.

6. A surface acoustic wave device, the surface acoustic wave device being a filter or a multiplexer, the filter or the multiplexer comprising a resonator, characterized in that: The resonator is the surface acoustic wave resonator as claimed in claim 5 above.

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