High-performance acoustic wave filter and acoustic wave resonator

Abstract

The invention relates to the technical field of filter design, in particular to a high-performance acoustic wave filter which comprises at least two series resonators sequentially connected in series. An intermediate node of every two series resonators is connected with the parallel resonator; the series resonator and the parallel resonator at least comprise a four-layer structure of an acoustic mirror, an upper electrode, a piezoelectric layer and a lower electrode, and the overlapped area of the four-layer structure in the vertical direction is an effective area of the resonator; and the roundness of the effective area pattern of the series resonator or the parallel resonator is set according to the classification condition of the filter. According to the technical scheme, the Rp value of each resonator is adjusted by setting the shape of the effective region of the resonator without adding an additional process, so that the performance of different types of filters is improved.

Description

Technical Field

[0001] This invention relates to the field of filter design technology, specifically to a high-performance acoustic filter and acoustic resonator. Background Technology

[0002] With the rapid development of communication technology, filters, as core components for signal gating, face increasingly stringent requirements for key performance indicators such as insertion loss (IL). Resonators, as core components of filters, directly affect the overall performance of the filter due to the magnitude of their parallel resonant impedance (Rp). Improving the Rp value of a specific resonator is one of the key ways to optimize filter performance.

[0003] In existing technologies, to improve the Rp value of resonators, special structures such as air wings, air bridges, recesses, or protrusions are typically added to optimize the mechanical vibration characteristics of the resonator and thus improve Rp. First, these methods require additional process steps and structural designs during resonator fabrication, significantly increasing process complexity and raising filter manufacturing costs, which is detrimental to mass production and cost control. Furthermore, as communication technologies evolve towards higher frequencies and higher bandwidths, the demand for filter Rp is further increasing, and existing methods relying on additional structures are insufficient to meet the practical application requirements of simultaneously improving Rp value while simplifying processes and controlling costs. Moreover, in some scenarios with lower Rp requirements, existing technologies cannot reduce costs by simplifying the structure, resulting in insufficient performance-cost compatibility.

[0004] Therefore, there is an urgent need for a technical solution that does not require additional processes or increase process complexity to effectively improve the Rp value of the resonator, thereby optimizing the filter performance. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a high-performance acoustic filter and acoustic resonator to solve the problem that the existing technology for improving the Rp value of the resonator requires additional processes and increases the complexity of the process.

[0006] According to a first aspect of the present invention, a high-performance acoustic filter is provided, comprising: At least two series resonators connected in series; the intermediate node of each pair of series resonators is connected to a parallel resonator; The resonator comprises at least four layers: an acoustic mirror, an upper electrode, a piezoelectric layer, and a lower electrode. The region where the four layers overlap in the vertical direction is the effective region of the resonator. The roundness of the effective region pattern of the series resonator or the parallel resonator is set according to the classification of the filter.

[0007] Preferably, in the high-performance acoustic filter, if the filter is classified as a bandpass filter, the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, and the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator; each series resonator in the filter is not provided with a mass load layer, or the thickness of the mass load layer of each series resonator is less than the thickness of the mass load layer of any parallel resonator.

[0008] Preferably, in the high-performance acoustic filter, if the filter is classified as a high-passband stop filter, the resonator is required to meet a preset performance requirement in the right-hand band of the passband. If the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, then the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

[0009] Preferably, in the high-performance acoustic filter, if the filter is classified as a high-passband stop filter, the resonator is required to meet a preset performance requirement in the left-hand band of the passband. If the roundness of the effective region pattern of at least one series resonator in the filter is greater than a preset threshold, and the roundness of the effective region pattern of at least one parallel resonator in the filter is less than the roundness of the effective region pattern of the series resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

[0010] Preferably, in the high-performance acoustic filter, the filter is classified as a low-passband stop filter. If the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, then the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

[0011] Preferably, the formula for calculating the roundness of the effective region pattern of the series resonator or the parallel resonator is: Roundness =

[0012] Where S is the area of ​​the effective region of the resonator, and Perimeter is the perimeter of the effective region of the resonator.

[0013] Preferably, the high-performance acoustic filter is a T-type filter with a number of stages greater than or equal to 2.

[0014] According to a second aspect of the present invention, an acoustic resonator is provided, comprising: The resonator has a four-layer structure consisting of an acoustic mirror, an upper electrode, a piezoelectric layer, and a lower electrode. The region where the four layers overlap in the vertical direction is the effective region of the resonator. The roundness of the effective region pattern of the resonator is greater than a preset threshold.

[0015] Preferably, the acoustic resonator includes: The effective region of the resonator can be a circle, an ellipse, a closed shape composed of multiple Bézier curves, or a polygon.

[0016] Preferably, the acoustic resonator includes: The preset threshold for the roundness of the effective region pattern of the resonator is 0.8.

[0017] The technical solution provided by this invention may include the following beneficial effects: It is understood that the high-performance acoustic filter disclosed in this invention includes at least two series resonators connected in series; the intermediate node of each pair of series resonators is connected to a parallel resonator; the series resonator and the parallel resonator each include at least a four-layer structure consisting of an acoustic mirror, an upper electrode, a piezoelectric layer, and a lower electrode, with the overlapping area of ​​the four layers in the vertical direction being the effective region of the resonator; the roundness of the effective region shape of the series or parallel resonator is set according to the filter classification. This technical solution, without adding extra processes, adjusts the Rp value of each resonator by setting the shape of the effective region of the resonator, thereby improving the performance of different types of filters.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0020] Figure 1 This is a schematic diagram of the structure of a high-performance acoustic filter according to an exemplary embodiment; Figure 2 This is a top view schematic diagram of the upper and lower electrodes of an acoustic resonator according to an exemplary embodiment; Figure 3 This is a graph showing the impedance versus frequency according to an exemplary embodiment; Figure 4This is a graph illustrating the variation of the impedance at the parallel resonant point with the roundness of the resonator according to an exemplary embodiment. Figure 5 This is a comparison graph of bandpass filter performance curves according to an exemplary embodiment; Figure 6 This is a performance curve comparison diagram of a high-pass band-stop filter according to an exemplary embodiment; Figure 7 This is a comparison graph of the performance curves of a low-passband-stop filter according to an exemplary embodiment; Figure 8 This is a top view schematic diagram of an ellipse with a roundness deviation of 1 in the effective area pattern according to an exemplary embodiment; Figure 9 This is a top view schematic diagram of a pentagon with a roundness of approximately 1, illustrating an effective area graphic according to an exemplary embodiment; Figure 10 This is a graph illustrating the change in impedance of the parallel resonant point as a function of the aspect ratio of the resonator, according to an exemplary embodiment. Detailed Implementation

[0021] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0022] In one embodiment, Figure 1 This is a schematic diagram illustrating the structure of a high-performance acoustic filter according to an exemplary embodiment. See also... Figure 1 A high-performance acoustic filter is provided, comprising: At least two series resonators connected in series; the middle node of each pair of series resonators is connected to a parallel resonator.

[0023] High-performance acoustic filters can be T-type filters with a number of stages greater than or equal to 2. As a preferred embodiment, see [link to example]. Figure 1 The number of series resonators is three, namely a first series resonator 101, a second series resonator 102 and a third series resonator 103 connected in series. The middle node of the first series resonator 101 and the second series resonator 102 is connected to the first parallel resonator 104. The middle node of the second series resonator 102 and the third series resonator 103 is connected to the second parallel resonator 105.

[0024] In practice, the middle node of every two series resonators is connected to a parallel resonator. The parallel resonator here can be a single parallel resonator, or two or more parallel resonators can be set according to the actual situation.

[0025] The resonator comprises at least four layers: an acoustic mirror, an upper electrode, a piezoelectric layer, and a lower electrode. The region where the four layers overlap in the vertical direction is the effective region of the resonator. (See also...) Figure 2 This is a schematic diagram of the effective region of a resonator. Figure 2 In the diagram, B1 is the upper electrode and T1 is the lower electrode. The acoustic mirror can be a cavity or a Bragg acoustic mirror.

[0026] The roundness of the effective region pattern of the series resonator or the parallel resonator is set according to the classification of the filter.

[0027] A single resonator employs a sandwich structure consisting of an upper electrode, a piezoelectric layer, and a lower electrode, enabling the mutual conversion between electrical and acoustic signals. When input electrical signals of different frequencies, its impedance varies with frequency as follows: Figure 3 As shown in the Z1 or Z2 curve (curves corresponding to the right-hand coordinate axis): the lowest point of the curve is the series resonant point, the frequency corresponding to the horizontal axis is called the series resonant frequency (Fs), and the impedance corresponding to the vertical axis is called the series resonant impedance (Rs); the highest point of the curve is the parallel resonant point, the frequency corresponding to the horizontal axis is called the parallel resonant frequency (Fp), and the impedance corresponding to the vertical axis is called the parallel resonant impedance (Rp). At the corresponding resonant frequency, the lower the Rs or the higher the Rp, the smaller the electrical loss at that frequency.

[0028] like Figure 1 As shown, a single resonator is designed as a filter through circuit design. Because it allows signals between 2.1 GHz and 2.25 GHz to pass through while blocking other signals, it is called a bandpass filter. The range of electrical signals that can pass through is called the passband. The electrical curve of the filter is shown in the figure. Figure 3 As shown in S21, for a bandpass filter, the frequency of the series resonator is higher (electrical curve Z1), while the frequency of the parallel resonator is lower (electrical curve Z2).

[0029] See Figure 4 The diagram shows the variation of the impedance of the parallel resonant point of a single resonator with the roundness of the resonator. It can be seen that the closer the roundness of the effective region of the resonator is to 1, the greater the impedance (Rp) of its parallel resonator. Therefore, the technical solution shown in this embodiment can specifically set the shape of the effective region of the resonator in the filter according to the classification of the filter. By using effective region shapes with different roundness, the performance of the filter can be improved without adding additional processes.

[0030] In one embodiment, in the high-performance acoustic filter, if the filter is classified as a bandpass filter, then the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, and the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator; each series resonator in the filter is not provided with a mass load layer, or the thickness of the mass load layer of each series resonator is less than the thickness of the mass load layer of any parallel resonator.

[0031] For a T-type bandpass filter, insertion loss (IL) is the core performance indicator (measured in dB), used to characterize the degree of energy loss during signal transmission. For the passband of the filter, energy loss must be minimized to ensure signal transmission quality. Therefore, in terms of resonator parameters, the series resonant impedance (Rs) of the series resonator should be as low as possible, and the parallel resonant impedance (Rp) of the parallel resonator should be as high as possible.

[0032] For FBAR (Thin Film Bulk Acoustic Resonator) filters, on the one hand, the weights of the Rs of the series resonator and the Rp of the parallel resonator on the overall filter performance differ; on the other hand, in addition to Rs and Rp, other parameters of the resonator (such as electromechanical coupling coefficient, frequency stability, etc.) also significantly affect the filtering effect. To balance the comprehensive performance of various parameters, practical designs typically require the parallel resonator to maintain a high impedance, while ensuring that the Rs value of the series resonator is low, and that its impedance characteristics are better in the frequency range below the series resonant frequency (Fs).

[0033] Assumption Figure 1 As a bandpass filter, the frequency of its parallel resonator is lower than that of the series resonator. Its performance relies heavily on the high parallel impedance of the parallel resonator. A high Rp value effectively enhances the parallel branch's ability to suppress out-of-band interference signals, reduces leakage and attenuation of useful signals, and thus significantly improves the filter's insertion loss (IL) performance. The closer the roundness of the resonator shape is to 1, the higher its Rp value. Therefore, in this bandpass filter, for the effective region of the parallel resonators 104 and 105, which require high Rp, a shape with a roundness closer to 1 is selected, directly improving their Rp value through shape optimization.

[0034] The resonant frequency of a parallel resonator is necessarily lower than that of a series resonator. According to the design principle of resonators, the lower the frequency, the larger the required mass load layer (ML) thickness. Therefore, by configuring a thicker ML for the parallel resonator (or setting an ML only for it), its low-frequency resonance requirements can be accurately matched, ensuring that the filtering frequency characteristics meet the design goals.

[0035] See the bandpass filter performance curve comparison chart. Figure 5 ,from Figure 5As can be seen, the bandpass filter shown in this embodiment outperforms the reference curve.

[0036] In one embodiment, in the high-performance acoustic filter, if the filter is classified as a high-passband stop filter, and the resonator is required to meet a preset performance requirement in the right-hand band of the passband. If the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, then the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

[0037] When a filter is a high-pass band-stop filter, its core function is to allow useful high-frequency signals to pass smoothly (high-pass characteristic) while precisely suppressing interference signals in a specific mid-frequency or low-frequency band (band-stop characteristic) to ensure the purity and stability of signal transmission. The "right side of the passband" specifically refers to the higher frequency region within the high-frequency passband that the filter allows to pass through. This region is often the transmission frequency band of critical signals in communication systems, and the requirements for signal transmission loss control and anti-interference capabilities are extremely stringent. The resonator performance needs to meet preset requirements; for example, the useful high-frequency signal needs to have minimal insertion loss (IL) during transmission to avoid signal strength attenuation affecting communication quality, while strictly blocking suppressed band-stop signals to prevent signal crosstalk from causing transmission distortion.

[0038] To address this, the parallel resonators of the filter need to have higher parallel impedance. A high Rp value can significantly enhance the ability of the parallel branch to suppress out-of-band interference signals and reduce the energy loss of useful high-frequency signals, thereby accurately matching the performance requirements of the right side of the passband. Therefore, the roundness of the effective region pattern of each parallel resonator in the filter needs to be greater than a preset threshold so that its roundness is closer to 1, thereby increasing the Rp value of the parallel resonators.

[0039] In this embodiment, the resonant frequency of the parallel resonator of the high-pass bandstop filter needs to be higher than that of the series resonator. Therefore, the series resonator needs to be equipped with a thicker ML, or only the series resonator is equipped with ML while the parallel resonator is not equipped with ML.

[0040] The performance curve comparison chart for this embodiment can be found in [link / reference]. Figure 6 ,from Figure 6 As can be seen, the bandpass filter shown in this embodiment outperforms the reference curve.

[0041] In one embodiment, in the high-performance acoustic filter, if the filter is classified as a high-passband stop filter, and the resonator is required to meet a preset performance requirement in the left-hand band of the passband. If the roundness of the effective region pattern of at least one series resonator in the filter is greater than a preset threshold, and the roundness of the effective region pattern of at least one parallel resonator in the filter is less than the roundness of the effective region pattern of the series resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

[0042] The high-passband stop filter in this embodiment requires the resonator to meet preset performance requirements in the left-hand band of the passband. The left-hand band specifically refers to the relatively low-frequency region within the high-frequency passband that the filter allows to pass through. Therefore, the series resonator, which serves as the backbone of signal transmission, needs to have a higher parallel impedance. Its Rp value directly determines the signal transmission efficiency and anti-interference capability on the left side of the passband. A high Rp value effectively reduces the energy loss of useful signals while enhancing the blocking effect against out-of-band interference signals.

[0043] In this embodiment, the resonant frequency of the parallel resonator of the high-pass bandstop filter needs to be higher than that of the series resonator. Therefore, the series resonator needs to be equipped with a thicker ML, or only the series resonator is equipped with ML while the parallel resonator is not equipped with ML.

[0044] In one embodiment, the high-performance acoustic filter is classified as a low-passband stop filter. If the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, then the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

[0045] When the filter is a low-passband stop filter, its core function is to allow lossless transmission of useful signals in the low-frequency band (low-pass characteristic) while precisely suppressing interference signals in a specific high-frequency band (band-stop characteristic). The parallel resonator is the core component for blocking high-frequency interference signals. It needs to effectively block high-frequency signals from the band-stop band from entering the low-frequency passband through its high parallel impedance (Rp) characteristic, avoiding crosstalk between the interference signal and the useful low-frequency signal, and reducing the energy loss of the useful low-frequency signal. Therefore, the parallel resonator requires a high Rp value. Thus, the roundness of the effective region pattern of each parallel resonator in the filter needs to be greater than a preset threshold to make its roundness closer to 1, thereby increasing the Rp value of the parallel resonator.

[0046] The resonant frequency of the parallel resonator in a low-pass band stop filter is higher than that of the series resonator. The series resonator needs to be equipped with a thicker ML, or only the series resonator needs to be equipped with an ML while the parallel resonator is not equipped with an ML.

[0047] According to another embodiment of the present invention, an acoustic resonator is provided, comprising: The resonator has a four-layer structure consisting of an acoustic mirror, an upper electrode, a piezoelectric layer, and a lower electrode. The area where the four layers overlap in the vertical direction is the effective region of the resonator. The roundness of the effective region pattern of the resonator is greater than a preset threshold.

[0048] Preferably, the effective region of the resonator is a circle, an ellipse, a closed shape composed of multiple Bézier curves, or a polygon. See also Figure 2 , Figure 8 and Figure 9 The shape of the effective region of the resonator can be different, as long as its roundness is close to 1, it can be used to improve the Rp value.

[0049] The formula for calculating the roundness of the effective region pattern of the resonator is: Roundness =

[0050] Where S is the area of ​​the effective region of the resonator, and Perimeter is the perimeter of the effective region of the resonator.

[0051] Preferred, from Figure 4 It can be seen that when the roundness is greater than 0.8, the normalized parallel impedance is significantly improved. Therefore, the preset threshold for the roundness of the effective region pattern of the resonator is 0.8.

[0052] In any of the above embodiments, the shape of the acoustic resonator can also be determined by its aspect ratio: The direction of the two furthest points on the edge of the effective area of ​​the resonator is taken as the longitudinal direction, and the direction perpendicular to the longitudinal direction is taken as the transverse direction; the average longitudinal width and the average transverse width of the effective area of ​​the resonator are calculated; the ratio of the average longitudinal width to the average transverse width is taken as the aspect ratio; the aspect ratio of the resonator is less than the preset aspect ratio.

[0053] See Figure 10 and Figure 4 The smaller the aspect ratio, the higher the normalized parallel impedance. Therefore, although the roundness (maximum 1) and the aspect ratio (minimum 1) are defined differently, their trends are basically the same.

[0054] Therefore, the shape of the effective region of the resonator can be determined by the aspect ratio.

[0055] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0056] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means at least two.

[0057] The scope of the preferred embodiments of the present invention includes other implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order, depending on the functions involved, as will be understood by those skilled in the art to which the embodiments of the present invention pertain.

[0058] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-performance acoustic filter, characterized in that, include: At least two series resonators connected in series; the middle node of each pair of series resonators is connected to a parallel resonator; The series resonator and the parallel resonator each include at least a four-layer structure consisting of an acoustic mirror, an upper electrode, a piezoelectric layer, and a lower electrode. The region where the four layers overlap in the vertical direction is the effective region of the resonator. The roundness of the effective region pattern of the series resonator or the parallel resonator is set according to the classification of the filter.

2. The high-performance acoustic filter according to claim 1, characterized in that, If the filter is classified as a bandpass filter; If the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, and the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator; Each series resonator in the filter has no mass load layer, or the mass load layer thickness of each series resonator is less than the mass load layer thickness of any parallel resonator.

3. The high-performance acoustic filter according to claim 1, characterized in that, If the filter is classified as a high-passband stop filter, and the resonator is required to meet the preset performance requirements in the right-hand band of the passband; If the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, then the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

4. The high-performance acoustic filter according to claim 1, characterized in that, If the filter is classified as a high-passband stop filter, and the resonator is required to meet the preset performance requirements in the left-hand band of the passband; If the roundness of the effective region pattern of at least one series resonator in the filter is greater than a preset threshold, then the roundness of the effective region pattern of at least one parallel resonator in the filter is less than the roundness of the effective region pattern of the series resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

5. The high-performance acoustic filter according to claim 1, characterized in that, If the filter is classified as a low-passband stop filter; If the roundness of the effective region pattern of at least one parallel resonator in the filter is greater than a preset threshold, then the roundness of the effective region pattern of at least one series resonator in the filter is less than the roundness of the effective region pattern of the parallel resonator. Each parallel resonator in the filter has no mass load layer, or the mass load layer thickness of each parallel resonator is less than the mass load layer thickness of any series resonator.

6. The high-performance acoustic filter according to claim 1, characterized in that, The formula for calculating the roundness of the effective region pattern of the series resonator or the parallel resonator is as follows: Roundness = Where S is the area of ​​the effective region of the resonator, and Perimeter is the perimeter of the effective region of the resonator.

7. The high-performance acoustic filter according to claim 1, characterized in that, The high-performance acoustic filter is a T-type filter with a number of stages greater than or equal to 2.

8. An acoustic resonator, characterized in that, At least including: The structure consists of four layers: an acoustic mirror, an upper electrode, a piezoelectric layer, and a lower electrode. The area where the four layers overlap in the vertical direction is the effective region of the resonator. The roundness of the effective region pattern of the resonator is greater than a preset threshold.

9. The acoustic resonator according to claim 8, characterized in that, include: The effective region of the resonator can be a circle, an ellipse, a closed shape composed of multiple Bézier curves, or a polygon.

10. The acoustic resonator according to claim 8, characterized in that, include: The preset threshold for the roundness of the effective region pattern of the resonator is 0.8.

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