A surface acoustic wave filter and signal processing circuit

Abstract

This application relates to the field of device fabrication technology, and provides a surface acoustic wave (SAW) filter and signal processing circuit, including a series branch resonator group and a parallel branch resonator group. The acoustic wave mode excited by the resonators in the series branch resonator group is a first-order antisymmetric Lamb wave mode, and the acoustic wave mode excited by the resonators in the parallel branch resonator group is a horizontal shear SAW mode. This application combines the first-order antisymmetric Lamb wave mode resonator and the horizontal shear SAW mode resonator, using a hybrid filter to build two different acoustic wave mode resonators. At low frequencies, the horizontal shear SAW mode resonator exhibits its stable characteristics, while at high frequencies, the first-order antisymmetric Lamb wave mode resonator generates a high-frequency mode. This approach can balance the low-frequency, low-cost design of the horizontal shear SAW mode resonator with the high-frequency, large-bandwidth advantages of the first-order antisymmetric Lamb wave mode resonator.

Description

Technical Field

[0001] This invention relates to the field of device fabrication technology, and in particular to a surface acoustic wave filter and signal processing circuit. Background Technology

[0002] Existing surface acoustic wave (SAW) filters mainly consist of resonators connected in series and parallel to excite a single SAW mode: horizontal shear SAW. Typically, the frequency of the series resonator in a SAW filter is higher than that of the parallel resonator. Because the speed of sound in the horizontal shear SAW mode is slow, exciting higher frequencies requires shortening the wavelength and electrode linewidth. However, due to limitations in electrode photolithography, the linewidth of the resonator for exciting the horizontal shear SAW mode cannot be reduced to below 1 μm, thus failing to meet the filter's requirements in terms of frequency and bandwidth. For example, assuming the speed of sound in the horizontal shear SAW mode is 4 km / s, shortening the wavelength to 1 μm would only allow a frequency up to 4 GHz, failing to cover frequencies above 4 GHz and thus not meeting the requirements of the 5G N77 band (3.3 GHz to 4.2 GHz). Summary of the Invention

[0003] To address the problem that existing series resonators based on excited horizontal shear surface acoustic wave modes cannot meet the high-frequency and high-bandwidth requirements of filters, embodiments of this application provide a surface acoustic wave filter and signal processing circuit.

[0004] According to a first aspect of this application, a surface acoustic wave filter is provided, comprising: a series branch resonator group and a parallel branch resonator group;

[0005] The acoustic wave mode excited by the resonators in the series branch resonator group is a first-order antisymmetric Lamb wave mode.

[0006] The acoustic wave mode excited by the resonators in the parallel branch resonator group is the horizontal shear surface acoustic wave mode.

[0007] Furthermore, the resonator in the series branch resonator group includes: a first supporting substrate, a first piezoelectric thin film, and a first metal electrode;

[0008] The first metal electrode includes a first bus bar, a second bus bar, a plurality of first interdigital electrodes and a plurality of second interdigital electrodes, wherein the first interdigital electrodes are connected to the first bus bar and the second interdigital electrodes are connected to the second bus bar;

[0009] A first piezoelectric thin film is disposed on a first supporting substrate;

[0010] The first metal electrode is disposed on the first piezoelectric film;

[0011] The first supporting substrate has a hollow groove;

[0012] The corresponding positions of the first interdigital electrode and the second interdigital electrode on the first supporting substrate coincide with the positions of the hollow groove.

[0013] Furthermore, the thickness of the first piezoelectric film is within the range of [300 nm, 600 nm];

[0014] The first center-to-center spacing corresponding to the first metal electrode is within the range [2μm, 20μm]; the first center-to-center spacing is the horizontal distance between the first interdigital electrode and the second interdigital electrode adjacent to the first interdigital electrode;

[0015] The metallization rate of the first metal electrode is within the range [0.05, 0.44].

[0016] The thickness of the first metal electrode is within the range of [75nm, 525nm].

[0017] Furthermore, the resonator in the parallel branch resonator group includes: a second supporting substrate, a second piezoelectric thin film, a second metal electrode, and a reflective gate electrode;

[0018] The second metal electrode includes a third bus bar, a fourth bus bar, multiple third interdigital electrodes, and multiple fourth interdigital electrodes. The third interdigital electrodes are connected to the third bus bar, and the fourth interdigital electrodes are connected to the fourth bus bar.

[0019] The reflective gate electrode includes a first reflective gate electrode and a second reflective gate electrode;

[0020] The second piezoelectric thin film is disposed on the second support substrate;

[0021] The second metal electrode is disposed on the second piezoelectric film;

[0022] The first and second reflective gate electrodes are symmetrically disposed on the second piezoelectric film relative to the second metal electrode.

[0023] Furthermore, the thickness of the second piezoelectric film is within the range of [300 nm, 1000 nm];

[0024] The second center spacing corresponding to the second metal electrode is within the range [0.5μm, 3μm]; the second center spacing is the horizontal distance between the third interdigital electrode and the fourth interdigital electrode adjacent to the third interdigital electrode.

[0025] The metallization rate of the second metal electrode is in the range [0.3, 0.6].

[0026] The thickness of the second metal electrode is within the range of [70nm, 155nm].

[0027] Furthermore, the ratio of the sound velocity frequency of the resonators in the parallel branch resonator group is equal to the second center spacing;

[0028] The sound velocity-to-frequency ratio of the resonators in the parallel branch resonator group is the ratio of the sound velocity of the horizontal shear surface acoustic wave mode to twice the frequency of the horizontal shear surface acoustic wave mode.

[0029] Furthermore, the resonators in the parallel branch resonator group also include: a dielectric layer;

[0030] The dielectric layer is disposed on the second support substrate.

[0031] Furthermore, the filter also includes an inductor-capacitor array;

[0032] Series branch resonator groups, parallel branch resonator groups, and inductor-capacitor groups are integrated and interconnected on the same substrate.

[0033] Furthermore, the series branch resonator groups and the parallel branch resonator groups are integrated and interconnected in the vertical direction.

[0034] According to a second aspect of this application, a signal processing circuit is provided, which includes the aforementioned surface acoustic wave filter.

[0035] The embodiments of this application have the following beneficial effects:

[0036] This application provides a surface acoustic wave (SAW) filter and signal processing circuit. The SAW filter includes a series branch resonator group and a parallel branch resonator group. The acoustic wave mode excited by the resonators in the series branch resonator group is a first-order antisymmetric Lamb wave mode, and the acoustic wave mode excited by the resonators in the parallel branch resonator group is a horizontal shear SAW mode. Based on this application, by combining the first-order antisymmetric Lamb wave mode resonator and the horizontal shear SAW mode resonator, the filter is constructed using a mixture of two different acoustic wave modes. At low frequencies, the horizontal shear SAW mode resonator utilizes its temperature characteristics, while at high frequencies, the first-order antisymmetric Lamb wave mode resonator generates a high-frequency mode. This approach balances the low-frequency, low-cost design of the horizontal shear SAW mode resonator with the high-frequency, large-bandwidth advantage of the first-order antisymmetric Lamb wave mode resonator. Furthermore, the first-order antisymmetric Lamb wave mode resonator only acts as a series resonator, requiring only one excitation frequency and one thin film thickness. Attached Figure Description

[0037] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the topology of an acoustic filter provided in an embodiment of this application;

[0039] Figure 2 This is a schematic cross-sectional view of a resonator in a series branch resonator group provided in an embodiment of this application;

[0040] Figure 3 This is a top view schematic diagram of a resonator in a series branch resonator group provided in an embodiment of this application;

[0041] Figure 4 This is a schematic cross-sectional view of a resonator in a parallel branch resonator group provided in an embodiment of this application;

[0042] Figure 5 This is a top view schematic diagram of a resonator in a parallel branch resonator group provided in an embodiment of this application;

[0043] Figure 6 This is a cross-sectional schematic diagram of a filter provided in an embodiment of this application;

[0044] Figure 7 This is a cross-sectional schematic diagram of a filter provided in an embodiment of this application;

[0045] Figure 8 This is a schematic diagram of a filter provided in an embodiment of this application;

[0046] Figure 9 This is a schematic diagram of a filter provided in an embodiment of this application;

[0047] Figure 10 This is a schematic diagram of the admittance response curve of a resonator in a series branch resonator group provided in an embodiment of this application;

[0048] Figure 11 This is a schematic diagram of the admittance response curve of a resonator in a parallel branch resonator group provided in an embodiment of this application;

[0049] Figure 12 This is a schematic diagram of the response curve of a filter provided in an embodiment of this application. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely one embodiment of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0051] The term "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. In the description of the embodiments of this application, it should be understood that the terms "first," "second," "third," and "fourth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," "third," and "fourth," etc., may explicitly or implicitly include one or more of that feature. Furthermore, the terms "first," "second," "third," and "fourth," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. In addition, the terms "comprising," "having," and "being," and any variations thereof, are intended to cover non-exclusive inclusion.

[0052] Surface acoustic wave (SAW) filters can be composed of multiple resonators cascaded in series and parallel arms. The resonant frequency of the series resonator is slightly higher than that of the parallel resonator, and the wavelength corresponding to the series resonator is slightly smaller than that of the parallel resonator. Generally, the resonant frequency *fr* of the series resonator needs to be roughly aligned with the resonant frequency *fa* of the parallel resonator to achieve the bandpass filter response. Therefore, the relative bandwidth of the filter is related to the electromechanical coupling coefficient *k* of the resonators. t 2 Positive correlation, k t 2 The larger the value, the greater the relative bandwidth of the filter that can be implemented.

[0053] The following describes a specific embodiment of an acoustic wave filter according to this application. Figure 1 This is a schematic diagram of the topology of an acoustic filter provided in an embodiment of this application. This specification provides the composition structure shown in the embodiments or accompanying drawings, but based on conventional or non-inventive labor, more or fewer resonators may be included. The composition structure listed in the embodiments is merely one of many possible compositions and does not represent the only possible composition structure. In actual implementation, the composition structure shown in the embodiments or accompanying drawings can be followed.

[0054] like Figure 1As shown, the surface acoustic wave (SAW) filter includes a series branch resonator group and a parallel branch resonator group. The resonators in the series branch resonator group and the resonators in the parallel branch resonator group all excite the same acoustic wave mode. The acoustic wave mode excited by the resonators in the series branch resonator group can be a first-order antisymmetric Lamb wave mode, while the acoustic wave mode excited by the resonators in the parallel branch resonator group can be a horizontal shear SAW mode. The series branch resonator group and the parallel branch resonator group can be electrically connected via electrical connection wires.

[0055] Figure 2 This is a schematic cross-sectional view of a resonator in a series branch resonator group provided in an embodiment of this application. Figure 3 This is a top view schematic diagram of a resonator in a series branch resonator group according to an embodiment of this application. The resonator in the series branch resonator group may include a first supporting substrate, a first piezoelectric thin film, and a first metal electrode. The first metal electrode may include a first busbar, a second busbar, a plurality of first interdigital electrodes, and a plurality of second interdigital electrodes. Each of the plurality of first interdigital electrodes can be connected to the first busbar, and each of the plurality of second interdigital electrodes can be connected to a second busbar. The first piezoelectric thin film may be disposed on the first supporting substrate, and the first metal electrode may be disposed on the first piezoelectric thin film. The first supporting substrate may have a hollow groove, and the corresponding positions of the first interdigital electrodes and the second interdigital electrodes on the first supporting substrate coincide with the positions of the hollow groove.

[0056] In some possible implementations, the thickness h of the first piezoelectric film in the resonator of the series branch resonator group can be within the range [300nm, 600nm], and the first center-to-center spacing corresponding to the first metal electrode can be within the range [2μm, 20μm]. The first center-to-center spacing l can be the horizontal distance between the first interdigital electrode and the second interdigital electrode adjacent to the first interdigital electrode. The metallization rate of the first metal electrode can be within the range [0.05, 0.44], i.e., the metallization rate of the first busbar, the second busbar, each first interdigital electrode, and each second interdigital electrode can be 5% to 44%. The thickness of the first metal electrode can be within the range [75nm, 525nm], i.e., the thickness of the first busbar, the second busbar, each first interdigital electrode, and each second interdigital electrode can be 75nm to 525nm.

[0057] In some possible implementations, the resonant frequencies of the resonators in the series branch resonator group need to satisfy the following condition:

[0058]

[0059] Among them, v tThis can represent the longitudinal velocity of a first-order antisymmetric Lamb wave mode, v. l This can represent the transverse velocity of the first-order antisymmetric Lamb wave mode. The longitudinal velocity can refer to the thickness direction of the first piezoelectric film, and the transverse velocity can refer to the velocity perpendicular to the first metal electrode.

[0060] In some possible implementations, the first supporting substrate can be any one of monocrystalline silicon, polycrystalline silicon, quartz, silicon carbide, α-alumina, and diamond. The first piezoelectric thin film can be a single-layer thin film composed of lithium niobate, or a single-layer thin film composed of lithium tantalate. Alternatively, the first piezoelectric thin film can be a multilayer thin film composed of lithium niobate and quartz, or a multilayer thin film composed of lithium niobate and aluminum nitride, or a multilayer thin film composed of lithium niobate, quartz, and aluminum nitride. The material of the first metal electrode can include at least one of aluminum, gold, titanium, nickel, molybdenum, and platinum. The first metal electrode can be an alloy composed of two of the above materials, or it can be a multilayer electrode.

[0061] In some possible implementations, the crystal cut of the first piezoelectric film in the resonator of the series branch resonator group can be a rotated Y-cut, with a corresponding Euler angle of (0,β,0), where -80° < β < 20°. The crystal cut of the first piezoelectric film can be a rotated Z-cut, with a corresponding Euler angle of (α,0,0), where α can be any angle.

[0062] Figure 4 This is a schematic cross-sectional view of a resonator in a parallel branch resonator group provided in an embodiment of this application. Figure 5 This is a top view schematic diagram of a resonator in a parallel branch resonator group according to an embodiment of this application. The resonator in the parallel branch resonator group may include a second supporting substrate, a second piezoelectric thin film, a second metal electrode, and a reflective gate electrode. The second metal electrode may include a third busbar, a fourth busbar, a plurality of third interdigital electrodes, and a plurality of fourth interdigital electrodes. Each of the plurality of third interdigital electrodes can be connected to a third busbar, and each of the plurality of fourth interdigital electrodes can be connected to a fourth busbar. The reflective gate electrode may include a first reflective gate electrode and a second reflective gate electrode. The second piezoelectric thin film may be disposed on the second supporting substrate, the second metal electrode may be disposed on the second piezoelectric thin film, and the first and second reflective gate electrodes may be symmetrically disposed on the second piezoelectric thin film relative to the second metal electrode.

[0063] In some possible implementations, the thickness of the second piezoelectric film in the resonator of the parallel branch resonator group can be within the range of [300 nm, 1000 nm], and the second center-to-center spacing corresponding to the second metal electrode can be within the range of [0.5 μm, 3 μm]. The second center-to-center spacing can be the horizontal distance between the third interdigital electrode and the fourth interdigital electrode adjacent to the third interdigital electrode. The metallization rate of the second metal electrode can be within the range of [0.3, 0.6], i.e., the metallization rate of the third busbar, the fourth busbar, each third interdigital electrode, and each fourth interdigital electrode can be 3% to 6%. The thickness of the second metal electrode can be within the range of [70 nm, 155 nm], i.e., the thickness of the third busbar, the fourth busbar, each third interdigital electrode, and each fourth interdigital electrode can be 70 nm to 155 nm.

[0064] In some possible implementations, the velocity-to-frequency ratio of the resonators in the parallel branch resonator group can be equal to the second center spacing. Specifically, the velocity-to-frequency ratio of the resonators in the parallel branch resonator group can be the ratio of the velocity of the horizontal shear surface acoustic wave mode to twice the frequency of the horizontal shear surface acoustic wave mode. The second center spacing can be the distance between the third interdigital electrode and the fourth interdigital electrode adjacent to the third interdigital electrode.

[0065] In some possible implementations, the second supporting substrate can be any one of monocrystalline silicon, polycrystalline silicon, quartz, silicon carbide, α-alumina, and diamond. The second piezoelectric thin film can be a single-layer thin film composed of lithium niobate, or a single-layer thin film composed of lithium tantalate. Alternatively, the second piezoelectric thin film can be a multilayer thin film composed of lithium niobate and quartz, or a multilayer thin film composed of lithium niobate and aluminum nitride, or a multilayer thin film composed of lithium niobate, quartz, and aluminum nitride. The second piezoelectric thin film can be a multilayer thin film composed of lithium tantalate and quartz, or a multilayer thin film composed of lithium niobate and aluminum nitride, or a multilayer thin film composed of lithium niobate, quartz, and aluminum nitride. The material of the second metal electrode can include at least one of aluminum, gold, titanium, nickel, molybdenum, and platinum. The second metal electrode can be an alloy composed of two of the above materials, or it can be a multilayer electrode.

[0066] In some possible implementations, the crystal cut of the second piezoelectric film in the resonator of the parallel branch resonator group can be X-cut, and the corresponding Euler angle can be (90°, 90°, γ), where 150° < γ < 180°; the crystal cut of the second piezoelectric film can be rotated Y-cut, and the corresponding Euler angle can be (0, θ, 0), where 30° < θ < 90°.

[0067] Figure 6This is a cross-sectional schematic diagram of a filter provided in an embodiment of this application, wherein the resonators in the series branch resonator group and the resonators in the parallel branch resonator group can be located in the same piezoelectric film layer, that is, the first piezoelectric film layer and the second piezoelectric film layer can be the same layer. Piezoelectric film materials of the same cut can be used, and the thickness of the piezoelectric film can be the same or different.

[0068] Figure 7 This is a cross-sectional schematic diagram of a filter provided in an embodiment of this application, wherein the series branch resonator group and the parallel branch resonator group can be integrated and interconnected in the vertical direction. For example... Figure 7 As shown, the resonators in the series branch resonator group and the resonators in the parallel branch resonator group can be located on different supporting substrates and different piezoelectric films. That is, the first supporting substrate and the second supporting substrate can be different supporting substrates, and the first piezoelectric film and the second piezoelectric film can be different piezoelectric films. The resonators in the series branch resonator group and the resonators in the parallel branch resonator group can be located on the same supporting substrate. That is, the first supporting substrate and the second supporting substrate can be the same layer, such as the material of the supporting substrate being silicon.

[0069] Figure 8 This is a schematic diagram of a filter provided in an embodiment of this application. Figure 9 This is a schematic diagram of a filter provided in an embodiment of this application. The filter may further include an inductor-capacitor group, and the series branch resonator group, parallel branch resonator group, and inductor-capacitor group can be integrated and interconnected on the same substrate. The capacitors and inductors in the inductor-capacitor group can be directly located on the supporting substrate. The series resonator group and parallel resonator group can be electrically interconnected on the supporting substrate.

[0070] The surface acoustic wave (SAW) filter provided in this application combines a first-order antisymmetric Lamb-mode resonator and a horizontal shear SAW-mode resonator. This mix of two different acoustic modes allows the filter to function effectively at low frequencies. At high frequencies, the horizontal shear SAW-mode resonator utilizes its temperature characteristics, while at high frequencies, the first-order antisymmetric Lamb-mode resonator generates a high-frequency mode. This approach balances the low-frequency, low-cost design of the horizontal shear SAW-mode resonator with the high-frequency, wide-bandwidth advantage of the first-order antisymmetric Lamb-mode resonator. Furthermore, the first-order antisymmetric Lamb-mode resonator functions only as a series resonator, requiring only one excitation frequency and one thin-film thickness.

[0071] The following example illustrates the performance of the surface acoustic wave filter in this application embodiment. Figure 10 This is a schematic diagram of the admittance response curve of a resonator in a series branch resonator group provided in an embodiment of this application. Figure 11This is a schematic diagram of the admittance response curve of a resonator in a parallel branch resonator group according to an embodiment of this application. The resonator in the series branch resonator group may include a silicon substrate, a 550nm lithium niobate piezoelectric film, and an aluminum electrode. The spacing between the two interdigitated electrodes in the aluminum electrode can be 15μm, the metallization of the electrode can be 0.1, the width of the electrode can be 1.5μm, the width of the busbar can be 45μm, the thickness of the electrode can be 90nm, and the lithium niobate can be Y124° cut. The acoustic wave mode excited by the resonator in the series branch resonator group can be a first-order antisymmetric Lamb wave mode, and the acoustic wave propagation direction can be along the X-axis of the piezoelectric film. The resonant frequency of the resonator in the series branch resonator group can be 3200MHz, and the anti-resonant frequency can be 3800MHz.

[0072] The resonators in the parallel branch resonator group can include a silicon carbide substrate, a 350 nm lithium niobate piezoelectric film, and an aluminum electrode. The spacing between the two interdigitated electrodes in the aluminum electrode can be 0.76 μm, the metallization rate can be 0.5, the electrode thickness can be 100 nm, and the lithium niobate can be X-cut. The acoustic wave mode excited by the resonators in the parallel branch resonator group can be a horizontal shear surface acoustic wave mode, and the angle between the acoustic wave propagation direction and the Y-axis of the piezoelectric film can be 170°. The resonant frequency of the resonators in the parallel branch resonator group can be 2800 MHz, and the anti-resonant frequency can be 3220 MHz.

[0073] Figure 12 This is a schematic diagram of the response curve of a filter provided in an embodiment of this application. The filter has a center frequency of 3.1 GHz, a passband of 2.9 GHz to 3.3 GHz, a passband ripple of 3 dB, and an out-of-band attenuation of 35 dB, thus realizing a high-performance, high-frequency, wide-bandwidth acoustic filter.

[0074] In this embodiment, the signal processing circuit may include multiple surface acoustic wave (SAW) filters, each SAW filter may include a series branch resonator group and a parallel branch resonator group. The acoustic wave mode excited by the resonators in the series branch resonator group may be a first-order antisymmetric Lamb wave mode, and the acoustic wave mode excited by the resonators in the parallel branch resonator group may be a horizontal shear SAW mode.

[0075] In some possible implementations, surface acoustic wave filters can be used in radio frequency signal processing circuits such as duplexers and multiplexers.

[0076] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, while this specification describes specific embodiments, other embodiments are also within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in the order shown in different embodiments and still achieve the desired results. Additionally, the processes depicted in the drawings do not necessarily require a specific order or sequence of connections to achieve the desired results.

[0077] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. The focus of each embodiment is to describe the differences from other embodiments.

[0078] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A surface acoustic wave filter, characterized in that, include: Series branch resonator groups and parallel branch resonator groups; The acoustic wave mode excited by the resonators in the series branch resonator group is a first-order antisymmetric Lamb wave mode. The resonator in the series branch resonator group includes: a first supporting substrate, a first piezoelectric thin film, and a first metal electrode; the first metal electrode includes a first bus bar, a second bus bar, a plurality of first interdigital electrodes, and a plurality of second interdigital electrodes, wherein the first interdigital electrodes are connected to the first bus bar, and the second interdigital electrodes are connected to the second bus bar; the first piezoelectric thin film is disposed on the first supporting substrate; the first metal electrode is disposed on the first piezoelectric thin film; the first supporting substrate has a hollow groove; the corresponding positions of the first interdigital electrodes and the second interdigital electrodes on the first supporting substrate coincide with the positions of the hollow groove; The acoustic wave mode excited by the resonators in the parallel branch resonator group is the horizontal shear surface acoustic wave mode.

2. The filter according to claim 1, characterized in that, The thickness of the first piezoelectric film is within the range of [300nm, 600nm]; The first center-to-center spacing of the first metal electrode is within the range [2μm, 20μm]; the first center-to-center spacing is the horizontal distance between the first interdigital electrode and the second interdigital electrode adjacent to the first interdigital electrode. The metallization rate of the first metal electrode is within the range [0.05, 0.44]. The thickness of the first metal electrode is within the range of [75nm, 525nm].

3. The filter according to claim 1, characterized in that, The resonator in the parallel branch resonator group includes: a second supporting substrate, a second piezoelectric thin film, a second metal electrode, and a reflective gate electrode; The second metal electrode includes a third bus bar, a fourth bus bar, a plurality of third interdigital electrodes and a plurality of fourth interdigital electrodes, wherein the third interdigital electrodes are connected to the third bus bar and the fourth interdigital electrodes are connected to the fourth bus bar; The reflective gate electrode includes a first reflective gate electrode and a second reflective gate electrode; The second piezoelectric thin film is disposed on the second supporting substrate; The second metal electrode is disposed on the second piezoelectric film; The first reflective gate electrode and the second reflective gate electrode are symmetrically disposed on the second piezoelectric film relative to the second metal electrode.

4. The filter according to claim 3, characterized in that, The thickness of the second piezoelectric film is within the range of [300nm, 1000nm]; The second center-to-center spacing corresponding to the second metal electrode is within the range [0.5μm, 3μm]; the second center-to-center spacing is the horizontal distance between the third interdigital electrode and the fourth interdigital electrode adjacent to the third interdigital electrode; The metallization rate of the second metal electrode is in the range [0.3, 0.6]. The thickness of the second metal electrode is within the range of [70nm, 155nm].

5. The filter according to claim 4, characterized in that, The sound velocity-to-frequency ratio of the resonators in the parallel branch resonator group is equal to the second center spacing; The sound velocity-to-frequency ratio of the resonators in the parallel branch resonator group is the ratio of the sound velocity of the horizontal shear surface acoustic wave mode to twice the frequency of the horizontal shear surface acoustic wave mode.

6. The filter according to claim 3, characterized in that, The resonators in the parallel branch resonator group further include: a dielectric layer; The dielectric layer is disposed on the second support substrate.

7. The filter according to claim 1, characterized in that, The filter also includes an inductor-capacitor array; The series branch resonator group, the parallel branch resonator group, and the inductor-capacitor group are integrated and interconnected on the same substrate.

8. The filter according to claim 1, characterized in that, The series branch resonator group and the parallel branch resonator group are integrated and interconnected in the vertical direction.

9. A signal processing circuit, characterized in that, Includes the surface acoustic wave filter according to any one of claims 1-8.

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