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

Abstract

The utility model 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, the surface acoustic wave resonator comprises a piezoelectric substrate and an electroacoustic transducer arranged on the working surface of the piezoelectric substrate; the electroacoustic transducer is connected with the piezoelectric substrate. According to the utility model, a good transverse mode inhibition effect can be realized.

Description

Technical Field

[0001] This utility model application relates to the field of radio frequency filtering technology, and in particular to an electroacoustic transducer, a surface acoustic wave resonator, and a surface acoustic wave device. Background Technology

[0002] Surface acoustic wave (SAW) devices, as frequency source devices, are widely used in communication, remote control, and alarm systems. However, traditional SAW devices often suffer from performance degradation due to stray waves generated by transverse modes. For example... Figure 1 The diagram shows the structure of a conventional electroacoustic transducer 100. A first reflector 15 and a second reflector 16 are arranged on both sides of the sound wave propagation direction of the electroacoustic transducer 100. The electroacoustic transducer 100 includes multiple electrode fingers 11 and multiple electrode fingers 12 arranged in a staggered manner. The starting end of electrode finger 11 is connected to busbar 13, and the end of electrode finger 11 is inserted between two adjacent electrode fingers 12 on opposite sides without contacting each other. The starting end of electrode finger 12 is connected to busbar 14, and the end of electrode finger 12 is inserted between two adjacent electrode fingers 11 on opposite sides without contacting each other. A pseudo-electrode 19 is connected to busbar 13, with the starting end of pseudo-electrode 19 directly connected to busbar 13. Pseudo-electrode 19 is disposed at the end of electrode finger 12 and... Between busbar 13, pseudo-finger electrode 19 and electrode finger 11 are arranged alternately; pseudo-finger electrode 2 18 is connected to busbar 2 14, and the beginning of pseudo-finger electrode 2 18 is directly connected to busbar 2 14. Pseudo-finger electrode 2 18 is located between the end of electrode finger 11 and busbar 2 14. Pseudo-finger electrode 2 18 and electrode finger 2 12 are arranged alternately. Electrode finger 11 and electrode finger 2 12 are collectively referred to as interdigitated electrodes. When the surface acoustic wave device uses a traditional electroacoustic transducer 100, it cannot effectively suppress the transverse mode of the surface acoustic wave device, resulting in large fluctuations in the passband. Therefore, it cannot be applied to high-performance surface acoustic wave devices. Thus, it is necessary to make technical improvements to the structure of the traditional electroacoustic transducer 100.

[0003] like Figure 2 As shown, the improved electroacoustic transducer 200 structure includes alternating electrode fingers 21 and 22. The length of electrode finger 21 in the excitation region gradually decreases from the middle to the end of the region, and the length of electrode finger 22 in the excitation region also gradually decreases from the middle to the end of the region. Electrode fingers 21 and 22 are collectively referred to as interdigitated electrodes. The electroacoustic transducer 200 does not have pseudo-finger electrodes. Figure 3As shown, the measured insertion loss / VSWR-frequency curves of the electroacoustic transducer 200 after application in a surface acoustic wave (SAW) device are presented. The curves show that the electroacoustic transducer 200 exhibits better transverse mode suppression than the traditional electroacoustic transducer 100, with reduced in-band ripple. However, due to the lack of pseudo-finger electrodes, the transducer 200 suffers from a phenomenon where the pseudo-finger electrodes cannot be peeled off during the actual fabrication of SAW devices (filters or multiplexers, etc.), leading to an increase in minimum insertion loss and VSWR. This affects the yield of the SAW device and may even damage its performance. Utility Model Content

[0004] This utility model application provides an electroacoustic transducer, a surface acoustic wave (SAW) resonator, and a SAW device, aiming to partially or completely solve the technical problem in the prior art where the interdigitated electrodes cannot be peeled off, resulting in increased minimum insertion loss (or minimum insertion loss for short) and standing wave ratio (VSWR), which affects the yield of SAW devices (filters or multiplexers, etc.) and may even damage their performance. This utility model application achieves a SAW device (filter or multiplexer, etc.) with good transverse mode suppression and easy fabrication by controlling the distance between the dummy electrodes and the interdigitated electrodes. To achieve the above objective, this utility model application adopts the following technical solution:

[0005] In a first aspect, an electroacoustic transducer includes: a plurality of first electrode fingers and a plurality of second electrode fingers arranged alternately along a first direction; the starting ends of the first electrode fingers are connected to a first busbar, and at least a portion of the ends of the first electrode fingers are inserted between two adjacent second electrode fingers on opposite sides; the starting ends of the second electrode fingers are connected to a second busbar, and at least a portion of the ends of the second electrode fingers are inserted between two adjacent first electrode fingers on opposite sides; the starting ends of first dummy electrodes are connected to the first busbar, and the ends of the first dummy electrodes are disposed between the ends of the second electrode fingers and the first busbar; the first dummy electrodes and first electrode fingers are alternately arranged along the first direction; the starting ends of the second dummy electrodes are connected to the second busbar, and the ends of the second dummy electrodes are disposed between the ends of the first electrode fingers and the second busbar; the second dummy electrodes and second electrode fingers are alternately arranged along the first direction; the first electrode fingers and second electrode fingers are arranged in a staggered manner along the first direction. The overlapping portions form an intersecting region, which includes: a middle region located on the middle side in the second direction; a first low-sound-velocity region formed on the middle region near the first busbar, and having a sound speed lower than that in the middle region; and a second low-sound-velocity region formed on the middle region near the second busbar, and having a sound speed 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 additions on the first electrode finger and the second electrode finger, respectively. The electroacoustic transducer includes a first distance g1 and a second distance g2, satisfying: g1≥2λ, g2≥2λ, where the first distance g1 is the distance from the end of the first electrode finger to the end of the first pseudo-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 pseudo-finger along the second direction, and λ is the wavelength of the sound wave.

[0006] Optionally, along the first direction, the width of the electrode finger mass extension is greater than the width 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 is greater than the thickness of the first dummy finger electrode and the second dummy finger electrode, where 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 comprising: 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, wherein the electroacoustic transducer is any of the electroacoustic transducers described in the first aspect above.

[0010] Thirdly, a surface acoustic wave (SAW) device, which is a filter or multiplexer, includes a resonator, said resonator being the SAW resonator described in the second aspect above.

[0011] In summary, this utility model application has the following beneficial technical effects:

[0012] (1) In this utility model application, by setting 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 standing wave ratio are smaller, the phenomenon of interdigital electrodes being unable to be peeled off is reduced or avoided, and at the same time, a good transverse mode suppression effect can be achieved.

[0013] (2) In this utility model application, along the first direction, the width of the electrode finger mass addition part is greater than the width of the first pseudo-finger electrode and the second pseudo-finger electrode, and along the third direction, the thickness of the electrode finger mass addition part is greater than the thickness of the first pseudo-finger electrode and the second pseudo-finger electrode. The geometric width of the electrode finger mass addition part is increased, so that the low sound speed region and the standard sound speed region form a clear sound wave velocity boundary. The low sound speed region is lower than the standard sound speed region. The sound speed difference forms a transverse constraint of the sound wave, which can concentrate the energy of the sound wave in the middle region, making the low sound speed region a "damping region" of the sound wave. This reduces the generation of parasitic modes (such as transverse modes or volume wave modes) and stray wave signals, reduces the impact on the yield of the surface acoustic wave device, and makes the surface acoustic wave device (filter or multiplexer, etc.) easier to process and manufacture, thus improving the performance stability of the surface acoustic wave device. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a conventional electroacoustic transducer 100 in the prior art;

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

[0016] Figure 3 This is a measured insertion loss / VSWR-frequency curve after the existing electroacoustic transducer 200 is applied to a surface acoustic wave device.

[0017] Figure 4 This is a structural schematic diagram of an electroacoustic transducer 400 according to this utility model application;

[0018] Figure 5 This is a measured insertion loss / VSWR-frequency curve of the electroacoustic transducer 400 of this utility model application after being applied to a surface acoustic wave device;

[0019] Figure 6 This is a schematic diagram of the structure of another electroacoustic transducer according to this utility model application (300).

[0020] Figure 7This is a measured insertion loss / VSWR-frequency curve of the electroacoustic transducer 300 of this utility model application after being applied to a surface acoustic wave device. Detailed Implementation

[0021] In the following description, numerous specific details are set forth to provide a more thorough understanding of this utility model application. However, it will be apparent to those skilled in the art that this utility model application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this utility model application.

[0022] Firstly, such as Figure 4 As shown, this utility model application provides an electroacoustic transducer 400, including: a plurality of first electrode fingers 1 and a plurality of second electrode fingers 2 arranged alternately along a first direction; the starting ends of the first electrode fingers 1 are connected to a first busbar 3, and at least a portion of the ends of the first electrode fingers 1 are inserted between two adjacent second electrode fingers 2 on opposite sides; the starting ends of the second electrode fingers 2 are connected to a second busbar 4, and at least a portion of the ends of the second electrode fingers 2 are inserted between two adjacent first electrode fingers 1 on opposite sides; the starting end of a first pseudo-finger electrode 9 is connected to the first busbar 3, and the end of the first pseudo-finger electrode 9 is disposed between the end of the second electrode finger 2 and the first busbar 3; along the first direction, the first pseudo-finger electrode 9 and the first electrode fingers 1 are arranged alternately; the starting end of a second pseudo-finger electrode 8 is connected to the second busbar 4, and the end of the second pseudo-finger electrode 8 is disposed between the end of the first electrode finger 1 and the second busbar 4; along the first direction, the second pseudo-finger electrode 8 and the second electrode fingers 2 are arranged alternately; in the first electrode fingers 1 and the second electrode fingers 2, the starting ends of the first electrode fingers 1 and the second electrode fingers 2 are arranged alternately; in the first direction, the starting ends of the first electrode fingers 1 and the second electrode fingers 2 are connected to the first busbar 3, and the ends of the second pseudo-finger electrodes 1 and 2 are disposed between the end of the first electrode fingers 1 and the second busbar 4; along the first direction, the second pseudo-finger electrode 9 and the first electrode fingers 1 are arranged alternately; in the first direction, the starting ends of the first electrode fingers 1 and the second electrode fingers 2 are connected to the first busbar 3, and the ends of the second pseudo-finger electrodes 1 and 2 are disposed between the end of the first electrode fingers 1 and the second electrode fingers 2; along the In the cross region DA formed by the overlapping portions of electrode fingers 2 along the first direction, the cross region DA includes: a middle region DB, located on the middle side in the second direction y; a first low sound velocity region, formed on the side of the middle region DB near the first busbar 3, and having a sound velocity lower than that in the middle region; and a second low sound velocity region, formed on the side of the middle region DB near the second busbar 4, 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 constituted by providing electrode finger mass addition portions 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 end of the first electrode finger 1 to the end of the first pseudo-finger electrode 8 along the second direction, and the second distance g2 is the distance from the end of the second electrode finger 2 to the end of the second pseudo-finger 9 along the second direction. λ is the wavelength of the sound wave.

[0023] In some embodiments, the first electrode finger 1 and the second electrode finger 2 are also collectively referred to as interdigitated electrodes. The first direction can be the arrangement direction of the first electrode finger 1 or the second electrode finger 2, or the x-axis direction, which is also the direction of sound wave propagation. The second direction can be the extension direction of the first electrode finger 1 or the second electrode finger 2, or the y-axis direction. The third direction can be the height direction of the electroacoustic transducer, or the z-axis direction. The first direction, the second direction, and the third direction intersect each other. Preferably, the first direction, the second direction, and the third direction are perpendicular to each other, i.e., they all form a 90-degree angle.

[0024] In some embodiments, in the intersection region DA formed by the overlapping portions of the first electrode finger 1 and the second electrode finger 2 along the first direction, the intersection region DA includes an intermediate region DB located on the middle side in the second direction y, a first outer region DC1 formed on the side of the intermediate region DB near the first busbar 3, and a second outer region DC2 formed on the side of the intermediate region DB near the second busbar 4. In the first outer region DC1, electrode finger mass addition portions 7 are provided on the first electrode finger 1 and the second electrode finger 2. By providing electrode finger mass addition portions 7 on the plurality of first electrode fingers 1 and the plurality of second electrode fingers 2, the sound speed in the first outer region DC1 becomes lower than the sound speed in the intermediate region DB, thereby constituting a first low sound speed region with a sound speed lower than the sound speed in the intermediate region DB. Similarly, in the second outer region DC2, by providing electrode finger mass addition portions 7 on the plurality of first electrode fingers 1 and the plurality of second electrode fingers 2, a second low sound speed region with a sound speed lower than the sound speed in the intermediate region DB is also constituted.

[0025] In some embodiments, two spaced electrode mass addition portions 7 are provided on the first electrode finger 1, and two spaced electrode mass addition portions 7 are provided on the second electrode finger 2. The electrode mass addition portions 7 may be electrode mass addition films, which may be made of metal materials, such as Pt.

[0026] In some embodiments, the electroacoustic transducer 400 has a first edge region DD1 on the outer side of the first outer region DC1 in the second direction y, the first edge region DD1 being located between the first outer region DC1 and the first busbar 3, and the first edge region DC1 being located between the middle region B and the first edge region DD1; similarly, the electroacoustic transducer 400 has a second edge region DD2 on the outer side of the second outer region DC2 in the second direction y, the second edge region DD2 being located between the second outer region DC2 and the second busbar 4, and the second edge region DC2 being located between the middle region DB and the second outer region DD2.

[0027] In some embodiments, a first electrode finger 1 and a first dummy electrode 9 are provided in the first edge region DD1, with the end of the first dummy electrode 9 disposed between the end of the second electrode finger 2 and the first busbar 3. In the second edge region D2, a second electrode finger 2 and a first dummy electrode 8 are provided, with the end of the second dummy electrode 8 disposed between the end of the first electrode finger 1 and the second busbar 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 intermediate region DB is set to VB, the sound velocity of the sound wave in the first outer region DC1 and the second outer region DC2 is set to VC, and the sound velocity of the sound wave in the first edge region DD1 and the second edge region DD2 is set to VD, satisfying: VC < VB < VD. Accordingly, 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 intermediate 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 As shown, firstly, 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 upper electrode finger mass attachment 7 of the first electrode finger 1, where the head end of the upper electrode finger mass attachment 7 of the first electrode finger 1 is connected to the second electrode finger 2) to the end of the first dummy finger electrode 8. Secondly, 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 upper electrode finger mass attachment 7 of the second electrode finger 2, where the head end of the upper electrode finger mass attachment 7 of the second electrode finger 2 is connected to the second electrode finger 2) to the end of the second dummy finger 9. Furthermore, for ease of description of the standard sound speed region, the first low-sound speed region, the second low-sound speed region, the first high-sound speed region, and the second… The characteristics of the high-speed sound region are simply illustrated by using straight lines to connect the intersection 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. The standard sound speed region, the first low-speed sound region, the second low-speed sound region, the first high-speed sound region, and the second high-speed sound region are also completely corresponding to the standard sound speed region, the first high-speed sound region, and the second high-speed sound region derived theoretically. This utility model application does not impose any special limitations on this.

[0030] In some embodiments, in the second direction y, the electroacoustic transducer 400 sequentially forms a first high-velocity region, a first low-velocity region, a standard-velocity region, a second low-velocity region, and a second high-velocity region. Correspondingly, sound waves can propagate at different speeds in different regions, exhibiting a regular, piston-like propagation pattern, which can be called a piston mode. Therefore, when the electroacoustic transducer 400 is used to form a surface acoustic wave device, the aforementioned piston mode can be utilized to effectively suppress stray noise caused by transverse modes.

[0031] like Figure 3 , Figure 7 and Figure 5 As shown in this utility model application, 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 and the minimum insertion loss is smaller, reducing or avoiding the phenomenon that the interdigitated electrodes cannot be peeled off, and reducing the impact on the yield and performance of the surface acoustic wave device.

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

[0033] In this utility model application, firstly, along the first direction, the width of the electrode finger mass addition portion 7 is greater than the width of the first pseudo-finger electrode 9 and the second pseudo-finger electrode 8. Along the third direction, the thickness of the electrode finger mass addition portion 7 is greater than the thickness of the first pseudo-finger electrode 9 and the second pseudo-finger electrode 8. The increased geometric width of the electrode finger mass addition portion 7 creates a clear sound wave velocity boundary between the low sound speed region and the standard sound speed region. The low sound speed region is lower than the standard sound speed region, and the sound speed 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 speed region a "damping zone" of the sound wave. This reduces the generation of parasitic modes (such as lateral modes or volume wave modes) and stray wave signals, reduces the impact on the yield of the surface acoustic wave device, and makes the surface acoustic wave device (filter or multiplexer, etc.) easier to process and manufacture. It also improves the performance stability of the surface acoustic wave device.

[0034] In some embodiments, a first reflector 5 and a second reflector 6 are provided on both sides of the sound wave propagation direction of the electroacoustic transducer 400. The first reflector 5 and the second reflector 6 each include multiple reflector electrode fingers and a third bus bar and a fourth bus bar that are opposite to each other in the extension 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 are existing technologies in surface acoustic wave devices, and this utility model application will not elaborate on them further.

[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 of the electroacoustic transducers described in the first aspect above.

[0036] In some embodiments, the piezoelectric substrate is the fundamental component of the surface acoustic wave (SAW) device. The piezoelectric substrate is typically made of a material exhibiting piezoelectric effect, such as lithium niobate (LiNbO3), lithium tantalate (LiTaO3), quartz, zinc oxide (ZnO), or aluminum nitride (AlN). The piezoelectric substrate serves as a medium for sound wave propagation and generates mechanical vibrations under the influence of an electric field; conversely, it can also convert these mechanical vibrations into electrical signals. 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 is a technology found in existing SAW devices, and will not be described further in this application.

[0037] Thirdly, a surface acoustic wave (SAW) device, wherein the SAW device is a filter or multiplexer, the filter or multiplexer including a resonator, said resonator being any of the SAW resonators described in the second aspect above.

[0038] In some embodiments, a filter or multiplexer can be used as the surface acoustic wave device of this utility model application. The filter or multiplexer may include a resonator, which may be a surface acoustic wave resonator as described in any of the second aspects above.

[0039] (1) Test Result Terminology

[0040] VSWR: VSWR is an important indicator of the passband flatness of a filter. The closer the VSWR is to 1, the flatter the passband of the filter is. 3dB bandwidth: Bandwidth is an important indicator of the performance of an RF device. It is usually the difference between the upper cutoff frequency and the lower cutoff frequency when the insertion loss of the RF device is -3dB.

[0041] (2) Comparison of test conditions

[0042] Test example: Figure 6As shown, an electroacoustic transducer 300 includes: a plurality of first electrode fingers 1 and a plurality of second electrode fingers 2 arranged alternately along a first direction; the starting ends of the first electrode fingers 1 are connected to a first busbar 3, and at least a portion of the ends of the first electrode fingers 1 are inserted between two adjacent second electrode fingers 2 on opposite sides; the starting ends of the second electrode fingers 2 are connected to a second busbar 4, and at least a portion of the ends of the second electrode fingers 2 are inserted between two adjacent first electrode fingers 1 on opposite sides; the starting end of a first dummy electrode 9 is connected to the first busbar 3, and the end of the first dummy electrode 9 is disposed between the end of the second electrode fingers 2 and the first busbar 3; along the first direction, the first dummy electrode 9... The first electrode finger 1 is arranged alternately; the beginning of the second pseudo-electrode 8 is connected to the second busbar 4, and the end of the second pseudo-electrode 8 is located between the end of the first electrode finger 1 and the second busbar 4. Along the first direction, pseudo-electrode 18 and electrode finger 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 end of the first electrode finger 1 to the end of the first pseudo-electrode 8 along the second direction, and the second distance g2 is the distance from the end of the second electrode finger 2 to the end of the second pseudo-electrode 9 along the second direction, where λ is the wavelength of the sound wave. Thus, in the test example, the electroacoustic transducer 300 (such as...) Figure 5 The electroacoustic transducer 400 described in the embodiments of this utility model application (as described above) and the electroacoustic transducer 400 in the present utility model application (e.g.) Figure 4 The only difference is that the first distance g1 and the second distance g2 are less than twice the wavelength of the sound wave; all other test parameters and conditions are the same.

[0043] (3) Comparison of test results

[0044] like Figure 3 The figure shows the measured insertion loss / VSWR-frequency curve of the surface acoustic wave (SAW) device of the electroacoustic transducer 200. The SAW device has a center frequency of 1225 MHz and a 3 dB bandwidth of 180 MHz.

[0045] The surface acoustic wave (SAW) device exhibits a minimum insertion loss of -1.10 dB, out-of-band rejection of greater than 35 dB, and a standing wave ratio (VSWR) of less than 1.7. The curves show that the VSWR exceeds 2, resulting in significant jitter within the passband.

[0046] like Figure 7 The figure shows the measured insertion loss / VSWR-frequency curve of the surface acoustic wave (SAW) device of the electroacoustic transducer 300. The SAW device has a center frequency of 1224 MHz and a 3 dB bandwidth of 174 MHz.

[0047] The device exhibits a minimum insertion loss of -1.35 dB, out-of-band rejection of greater than 35 dB, and a standing wave ratio (SWR) of less than 2.5. As can be seen from the curves, the SWR of the surface acoustic wave device equipped with the electroacoustic transducer 300 exceeds 2, resulting in significant jitter within the passband. This is attributed to the excessively small first distance g1 and second distance g2.

[0048] like Figure 5 The figure shows the measured insertion loss / VSWR-frequency curves of a surface acoustic wave (SAW) device equipped with an electroacoustic transducer 400. The SAW device has a center frequency of 1225 MHz, a 3 dB bandwidth of 182 MHz, a minimum insertion loss of -1.06 dB, out-of-band rejection greater than 35 dB, and a VSWR less than 1.6. As can be seen from the curves, compared to the SAW device equipped with an electroacoustic transducer 300, the SAW device equipped with an electroacoustic transducer 400 has a flatter passband and lower 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 standing wave ratio are smaller, the phenomenon of interdigital electrodes being unable to be peeled off is reduced or avoided, and a good transverse mode suppression effect can be achieved.

[0050] The above descriptions are merely preferred embodiments of this utility model application, and this utility model application is not limited to the above embodiments. It is understood that other improvements and variations that are directly derived or conceived by those skilled in the art without departing from the spirit and concept of this utility model application should be considered to be included within the protection scope of this utility model application.

[0051] As stated above, although this utility model application has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the utility model application itself. Various changes in form and detail may be made to this utility model application without departing from the spirit and scope of the appended claims as defined.

Claims

1. An electro-acoustic transducer comprising: Multiple first electrode fingers and multiple second electrode fingers are arranged in a staggered manner along a first direction. The starting ends of the first electrode fingers are connected to a first busbar, and at least a portion of the ends of the first electrode fingers are inserted between two adjacent second electrode fingers on opposite sides. The starting ends of the second electrode fingers are connected to a second busbar, and at least a portion of the ends of the second electrode fingers are inserted between two adjacent first electrode fingers on opposite sides. The starting ends of the first dummy electrode are connected to the first busbar, and the ends of the first dummy electrode are located between the ends of the second electrode fingers and the first busbar. Along the first direction, the first dummy electrode and the first electrode fingers are arranged alternately. The starting ends of the second dummy electrode are connected to the second busbar, and the ends of the second dummy electrode are located between the ends of the first electrode fingers and the second busbar. Along the first direction, the second dummy electrode and the second electrode fingers are arranged alternately. In the intersection region formed by the overlapping portions of the first electrode finger and the second electrode finger along the first direction, the intersection region includes: an intermediate region located on the middle side in the second direction; a first low-sound-velocity region formed in the intermediate region near the first busbar side, and having a sound velocity lower than that in the intermediate region; and a second low-sound-velocity region formed in the intermediate region near the second busbar side, 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 providing electrode finger mass addition portions on the first electrode finger and the second electrode finger, respectively; 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 being the distance from the end of the first electrode finger to the end of the first pseudo-finger electrode along the second direction, the second distance g2 being the distance from the end of the second electrode finger to the end of the second pseudo-finger along the second direction, and λ being the wavelength of the sound wave.

2. The electro-acoustic transducer of claim 1, wherein, Along the first direction, the width of the electrode finger mass addition is greater than the width of the first pseudo-finger electrode and the second pseudo-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 is greater than the thickness of the first pseudo-finger electrode and the second pseudo-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, and a first reflector and a second reflector are set 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 disposed on the working surface of the piezoelectric substrate; the electroacoustic transducer is connected to the piezoelectric substrate, wherein the electroacoustic transducer is the electroacoustic transducer as described in any one of claims 1-4.

6. A surface acoustic wave (SAW) device, wherein the SAW device is a filter or multiplexer, the filter or multiplexer including a resonator, characterized in that, The resonator is the surface acoustic wave resonator as described in claim 5.

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