Filter, communication apparatus, and electronic device

Abstract

Provided in the present application are a filter, a communication apparatus, and an electronic device. The filter comprises: a piezoelectric layer, which has a first surface, the first surface comprising a first region and a second region that are spaced apart from each other; a dielectric layer, which is arranged in the first region; and a plurality of electrode structures, of which at least one is arranged on the dielectric layer, and at least one is arranged in the second region. The present application can improve the steepness of filters, thereby reducing insertion loss.

Description

Filters, communication devices and electronic equipment

[0001] This application claims priority to Chinese Patent Application No. 202510099318.8, filed on January 21, 2025, entitled "Filter, Communication Device and Electronic Equipment", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of filtering technology, and in particular to a filter, a communication device, and an electronic device. Background Technology

[0003] Surface acoustic wave (SAW) filters convert input electrical signals into ultrasonic waves that propagate on the surface and are ultimately converted back into electrical signals for output. During these two conversions, the input electrical signal is filtered. Due to their small size and high performance, they are widely used in electronic equipment.

[0004] In related technologies, surface acoustic wave (SAW) filters may include multiple resonators. To save on manufacturing processes and reduce production costs, some structural parameters of each resonator are identical. However, SAW filters have relatively high insertion loss. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a filter, a communication device, and an electronic device that can improve the steepness of the filter, thereby reducing insertion loss.

[0006] A first aspect of this application provides a filter, comprising: a piezoelectric layer, a dielectric layer, and a plurality of electrode structures. The piezoelectric layer has a first surface, the first surface including a spaced-apart first region and a second region. The dielectric layer is disposed on the first region of the piezoelectric layer. At least one electrode structure of the plurality of electrode structures is disposed on the dielectric layer, and at least one electrode structure of the plurality of electrode structures is disposed on the second region of the piezoelectric layer. For the electrode structure disposed on the dielectric layer, the electrode structure and a structure located below it (e.g., the dielectric layer and the piezoelectric layer, etc.) can form a resonator, and the resonator includes the dielectric layer. For the electrode structure disposed on the second region of the piezoelectric layer, the electrode structure and the piezoelectric layer located below it can form a resonator, and the resonator does not include the dielectric layer.

[0007] For resonators including a dielectric layer, the dielectric constant of the dielectric layer is typically small, which affects the electric field distribution between the electrodes and the piezoelectric layer, thus impacting the excitation efficiency of sound waves. Therefore, when a dielectric layer is placed between the piezoelectric layer and the electrode structure, the relative electromechanical coupling coefficient of the piezoelectric layer and the dielectric layer as a whole is smaller compared to a structure without a dielectric layer. Since the bandwidth of a resonator is related to the electromechanical coupling coefficient, adjusting the thickness of the dielectric layer can adjust the electromechanical coupling coefficient of the resonator, thereby adjusting the bandwidth. Furthermore, a larger dielectric layer thickness results in a smaller electromechanical coupling coefficient and a smaller bandwidth for the resonator.

[0008] When strong suppression is required near the passband of the filter, a steep drop in the passband insertion loss amplitude needs to be achieved within a narrow frequency band. In other words, the passband bandwidth and steepness must be balanced, so that the left and / or right shoulder steepness of the filter's output signal mutually constrains the bandwidth of the resonator. Therefore, by adjusting the resonator bandwidth by adjusting the thickness of the dielectric layer, the left and / or right shoulder steepness can be adjusted. Furthermore, a higher steepness is beneficial for achieving lower insertion loss.

[0009] The electromechanical coupling coefficient of a resonator excluding the dielectric layer is usually not adjustable, i.e., it is a fixed electromechanical coupling coefficient.

[0010] Therefore, the thickness of the dielectric layer can be adjusted according to actual needs, thereby adjusting the electromechanical coupling coefficient of the corresponding resonator, and then adjusting the bandwidth of the resonator. This can improve the left and / or right shoulder steepness of the filter output signal when there is a strong suppression requirement near the passband, thereby reducing the insertion loss of the filter.

[0011] In some embodiments of this application, the filter may be a trapezoidal surface acoustic wave filter, which may include multiple series resonators connected in series between the input and output terminals of the filter.

[0012] The multiple electrode structures include at least two first electrode structures. Each series resonator can be composed of a first electrode structure and a structure below it. Therefore, when the series resonator is connected in series between the input and output terminals of the filter, the first electrode structure is also connected in series between the input and output terminals of the filter. At least one first electrode structure is disposed on a dielectric layer. That is, at least one series resonator includes a dielectric layer. When there is a strong suppression requirement near the right shoulder of the passband, the electromechanical coupling coefficient of at least one series resonator can be adjusted to improve the steepness of the right shoulder of the filter output signal.

[0013] Furthermore, the first surface includes multiple spaced first regions, and the filter includes multiple dielectric layers, each disposed on one of the multiple first regions. At least two first dielectric layers are included among the multiple dielectric layers, and at least two first electrode structures are disposed on each of the at least two first dielectric layers. That is, at least two series resonators each include a first dielectric layer. Therefore, the electromechanical coupling coefficient of the at least two series resonators can be adjusted by adjusting the thickness of the at least two first dielectric layers. Thus, in this embodiment, the number of series resonators with adjustable electromechanical coupling coefficients is greater, thereby increasing the degree of freedom in improving the right shoulder steepness.

[0014] In some embodiments of this application, the thicknesses of at least two first dielectric layers are either the same or different. When the thicknesses of at least two first dielectric layers are the same, at least two first dielectric layers can be fabricated in the same process when manufacturing the filter. This simplifies the filter fabrication process, thereby improving manufacturing efficiency and reducing costs. When the thicknesses of the first dielectric layers in at least two series resonators are different, the electromechanical coupling coefficients of at least two series resonators are different, thereby increasing the degree of freedom in raising the right shoulder steepness.

[0015] In some embodiments of this application, the filter may include a trapezoidal surface acoustic wave filter, which may include multiple parallel resonators, one end of each parallel resonator being connected to a series resonator and the other end being connected to a ground terminal.

[0016] The multiple electrode structures also include at least two second electrode structures. Each parallel resonator can be composed of a second electrode structure and a structure below it. Therefore, when one end of the parallel resonator is connected to the series resonator and the other end is connected to the ground terminal, one end of the second electrode structure is connected to the series resonator of the filter, and the other end of the second electrode structure is connected to the ground terminal. At least one second electrode structure is disposed on a dielectric layer. That is, at least one parallel resonator includes a dielectric layer. When there is a strong suppression requirement near the left shoulder of the passband, the electromechanical coupling coefficient of at least one parallel resonator can be adjusted, thereby improving the steepness of the left shoulder of the filter output signal.

[0017] Furthermore, the filter includes multiple dielectric layers, each disposed on multiple first regions. Among the multiple dielectric layers are at least two second dielectric layers, and at least two second electrode structures are disposed on each of the at least two second dielectric layers. That is, at least two parallel resonators each include a second dielectric layer. Therefore, the electromechanical coupling coefficient of the at least two parallel resonators can be adjusted by adjusting the thickness of the at least two second dielectric layers. Thus, in this embodiment, the number of parallel resonators with adjustable electromechanical coupling coefficients is greater, thereby increasing the left shoulder steepness and enhancing the degree of freedom.

[0018] In some embodiments of this application, the thicknesses of at least two second dielectric layers are either the same or different. When the thicknesses of at least two second dielectric layers are the same, at least two second dielectric layers can be fabricated in the same process during filter fabrication. This simplifies the filter fabrication process, thereby improving manufacturing efficiency and reducing costs. When the thicknesses of the second dielectric layers in at least two parallel resonators are different, the electromechanical coupling coefficients of at least two parallel resonators are different, thereby increasing the degree of freedom in improving the left shoulder steepness.

[0019] In some embodiments of this application, the plurality of electrode structures includes at least two first electrode structures and at least two second electrode structures. The two ends of the first electrode structures are electrically connected to the input and output terminals of the filter, respectively. One end of the second electrode structure is connected to one end of a series resonator, and the other end of the second electrode structure is connected to a ground terminal. The filter includes multiple dielectric layers, each disposed on a plurality of first regions. The multiple dielectric layers include a first dielectric layer and a second dielectric layer. At least one first electrode structure is disposed on the first dielectric layer, and at least one second electrode structure is disposed on the second dielectric layer. The thickness of the first dielectric layer is different from the thickness of the second dielectric layer. The first electrode structure and the portion below it (e.g., the first dielectric layer and a piezoelectric layer) can form a series resonator, and the second electrode structure and the second dielectric layer and a voltage layer below it can form a parallel resonator. Furthermore, the thickness of the first dielectric layer in the series resonator is different from the thickness of the second dielectric layer in the parallel resonator. Therefore, the electromechanical coupling coefficient can be adjusted by the thickness of the first dielectric layer in the series resonator and by the thickness of the second dielectric layer in the parallel resonator, so that the electromechanical coupling coefficient of the series resonator is different from that of the parallel resonator, thereby achieving different steepness on both sides of the filter passband.

[0020] In some embodiments of this application, the filter may include a dual-mode surface acoustic wave (DMS) filter, and therefore, the multiple electrode structures may include at least two first electrode structures and at least two reflective gratings.

[0021] In one example, at least one first electrode structure or at least one reflective grating is disposed on the dielectric layer. Thus, the electromechanical coupling coefficient of at least one transducer unit or at least one reflective grating can be adjusted by changing the thickness of the dielectric layer, thereby improving the right and left shoulder steepness of the signal appearing in the filter.

[0022] In another example, the filter includes multiple dielectric layers, including a first dielectric layer and a second dielectric layer, a first electrode structure disposed on the first dielectric layer, and a reflective grating disposed on the second dielectric layer.

[0023] A second aspect of this application also provides a communication device including a power amplifier and a filter according to any of the above embodiments, wherein the power amplifier and the filter are electrically connected. The communication device is capable of achieving all the effects of the filter.

[0024] A third aspect of this application also provides an electronic device, including a circuit board and the aforementioned communication device, the communication device being disposed on the circuit board. The electronic device is capable of achieving all the effects of a filter. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application 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.

[0026] Figure 1 is a schematic diagram of the filter interface in the first embodiment of this application;

[0027] Figure 2 shows the relationship between the thickness of the dielectric layer in the filter shown in Figure 1 and the electromechanical coupling coefficient of the corresponding resonator.

[0028] Figure 3 is a schematic diagram of the filter structure in the second embodiment of this application;

[0029] Figure 4 is a schematic diagram of the filter topology in the third embodiment of this application;

[0030] Figure 5 is a schematic diagram of the planar structure of the filter shown in Figure 4;

[0031] Figure 6 is a schematic diagram of the cross-sectional structure at point AA in Figure 5;

[0032] Figure 7 is a schematic cross-sectional view of the filter in the fourth embodiment of this application;

[0033] Figure 8 is a schematic cross-sectional view of the filter in the fifth embodiment of this application;

[0034] Figure 9 is a schematic cross-sectional view of the filter in the sixth embodiment of this application;

[0035] Figure 10 is a cross-sectional structural diagram of the filter in the seventh embodiment of this application;

[0036] Figure 11 is a schematic cross-sectional view of the filter in the eighth embodiment of this application;

[0037] Figure 12 is a schematic diagram of the planar structure of the filter in the ninth embodiment of this application;

[0038] Figure 13 is a schematic diagram of the planar structure of the filter in the tenth embodiment of this application;

[0039] Figure 14 is a schematic diagram of the cross-sectional structure at BB in Figure 13;

[0040] Figure 15 shows the admittance curves obtained after simulation experiments of the filters of related technologies and the filter of this embodiment.

[0041] Figure 16 is a partially enlarged schematic diagram of the admittance curve shown in Figure 15;

[0042] Figure 17 is a schematic diagram of the planar structure of the filter in the eleventh embodiment of this application;

[0043] Figure 18 is a top view of Figure 17;

[0044] Figure 19 is a schematic diagram of the filter topology shown in Figure 17;

[0045] Figure 20 is a schematic diagram of the planar structure of the filter in the twelfth embodiment of this application;

[0046] Figure 21 is a schematic diagram of the planar structure of the filter in the thirteenth embodiment of this application.

[0047] Icons: 100 / 200 - Filter; 10 - Resonator; 11 - Piezoelectric layer; 111 - First surface; 1112 - Second region; 1113 - First region; 12 - Dielectric layer; 13 - Electrode structure; 133 - First electrode structure; 131 - First electrode; 132 - Second electrode; 133 - Transducer unit; 134 - Reflector grating; 14 - Low-velocity layer; 15 - High-velocity layer; 16 - Temperature compensation layer; 17 - Protective layer. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0049] In this article, the term "and / or" simply describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item)" refers to one or more, while "more" refers to two or more. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0050] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0051] Terms such as “connected” and “linked” are used to express the interconnection or interaction between different components, which may include direct connection or indirect connection through other components. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or apparatus is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Terms such as “upper,” “lower,” “left,” and “right” are used only relative to the orientation of components in the accompanying drawings. These directional terms are relative concepts used for relative description and clarification, and may vary accordingly depending on the orientation of the components in the drawings.

[0052] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0053] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units means two or more processing units; multiple systems means two or more systems.

[0054] This application provides an electronic device, which can be, for example, a server, consumer electronics, home electronics, in-vehicle electronics, financial terminal products, communication electronic products, etc., and this application does not limit the scope of the application. For example, the aforementioned consumer electronics can be mobile phones, tablet computers, laptops, personal computers (PCs), personal digital assistants (PDAs), smart wearable products (e.g., smartwatches, smart bracelets), virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, drones, etc. Home electronics can be smart door locks, televisions, smart speakers, refrigerators, robot vacuum cleaners, etc. In-vehicle electronic products can be in-vehicle navigation systems, in-vehicle displays, etc. Financial terminal products can be automated teller machines (ATMs), self-service electronic devices, etc. Communication electronic products can be servers, storage devices, radar, base stations, and other communication equipment.

[0055] Electronic devices include communication devices and circuit boards, with the communication devices mounted on the circuit boards. Communication devices can be, for example, radio frequency (RF) devices, RF modules, filter modules, etc.

[0056] The communication device may include a power amplifier and a filter, with the power amplifier and filter electrically connected. After receiving a signal, the communication device can perform filtering processing via the filter and power amplification processing via the power amplifier before outputting the signal.

[0057] The filter can be a surface acoustic wave (SAW) filter. In related technologies, the filter includes multiple resonators, each of which includes a stacked piezoelectric layer and an electrode structure. However, the insertion loss of filters in related technologies is relatively large.

[0058] Based on this, this application provides a filter that can reduce the insertion loss of the filter.

[0059] For ease of description, we first define three directions: X, Y, and Z. The X direction can be the length direction of filter 100, the Y direction can be the width direction of filter 100, and the Z direction can be the thickness direction of filter 100. Furthermore, the X, Y, and Z directions are all perpendicular to each other.

[0060] As shown in Figure 1, in this embodiment, the filter 100 can be a surface acoustic wave (SAW) filter. SAW filters are characterized by small size, high steepness, high suppression, and simple manufacturing process, and are widely used in communication devices such as radio frequency (RF) devices and RF modules.

[0061] The topologies commonly used in surface acoustic wave (SAW) filters mainly include trapezoidal SAW filters or double-mode SAW (DMS) filters.

[0062] As shown in Figure 1, the filter 100 may include a piezoelectric layer 11, a dielectric layer 12, and multiple electrode structures 13. The piezoelectric layer 11 is made of a piezoelectric material, specifically including 42YX-LiNbO3, 128YX-LiNbO3, etc. The piezoelectric layer 11 has a first surface 111, which may include spaced first regions 1113 and second regions 1112.

[0063] As shown in Figure 1, the dielectric layer 12 is disposed on the piezoelectric layer 11. Specifically, the dielectric layer 12 may be disposed on the first region 1113. The material of the dielectric layer 12 may include dielectric materials such as SiO2, SiN, Al2O3, AlN, AlScN, Si, or Ta2O5.

[0064] As shown in Figure 1, each electrode structure 13 may include a first electrode 131 and a second electrode 132. In one example, both the first electrode 131 and the second electrode 132 may be elongated structures and spaced apart. In another example, both the first electrode 131 and the second electrode 132 may be interdigitated electrodes.

[0065] As shown in Figure 1, at least one electrode structure 13 (e.g., electrode structure 13a) of the plurality of electrode structures 13 is disposed on the dielectric layer 12. At least one electrode structure 13 (e.g., electrode structure 13b) of the plurality of electrode structures 13 is disposed on the piezoelectric layer 11. It can be understood that, in this embodiment, the electrode structure 13 being disposed on the piezoelectric layer 11 may mean that the electrode structure 13 is disposed on the second region 1112 of the piezoelectric layer 11.

[0066] As shown in Figure 1, each electrode structure 13 and the structure below it can form a resonator 10. Therefore, this embodiment can form multiple resonators 10, and the number of resonators 10 is the same as the number of electrode structures 13. Specifically, for the electrode structure 13a disposed on the dielectric layer 12, the electrode structure 13a, the dielectric layer 12 and the piezoelectric layer 11 below it can form a resonator 10a, and the resonator 10a includes the dielectric layer 12. For the electrode structure 13b disposed on the piezoelectric layer 11, the electrode structure 13b and the piezoelectric layer 11 below it can form a resonator 10b, and the resonator 10b does not include the dielectric layer 12. It is understood that in the embodiments of this application, "does not include the dielectric layer" means that no dielectric layer 12 is disposed between the piezoelectric layer 11 and the electrode structure 13.

[0067] In this embodiment, when the filter 100 is applied, for each resonator 10, the first electrode 131 in the electrode structure 13 receives an electrical signal and transmits it to the piezoelectric layer 11. Since the piezoelectric layer 11 is made of piezoelectric material, it can generate a piezoelectric effect upon receiving the electrical signal, thus producing mechanical vibration, i.e., exciting sound waves. The mechanical vibration can then be converted into an electrical signal output through the inverse piezoelectric effect. Different frequencies result in different amplitudes of the mechanical vibration, thus completing the filtering process.

[0068] For the resonator 10a including the dielectric layer 12, since the dielectric constant of the dielectric layer 12 is usually small, this affects the electric field distribution between the electrode structure 13 and the piezoelectric layer 11, thereby affecting the excitation efficiency of the sound wave. Therefore, when the dielectric layer 12 is placed between the piezoelectric layer 11 and the electrode structure 13, the relative electromechanical coupling coefficient K2 of the piezoelectric layer 11 and the dielectric layer 12 as a whole is smaller than that of the structure without the dielectric layer 12. Since the bandwidth of the resonator 10a is related to the electromechanical coupling coefficient K2, the electromechanical coupling coefficient K2 of the resonator 10a can be adjusted by adjusting the thickness of the dielectric layer 12, thereby adjusting the bandwidth of the resonator 10a. Moreover, as shown in Figure 2, the larger the thickness of the dielectric layer 12, the smaller the electromechanical coupling coefficient K2, and the smaller the bandwidth of the resonator 10a.

[0069] When the left or right shoulder of filter 100 has strong suppression, a steep drop in the passband insertion loss amplitude needs to be achieved within a narrower frequency band. In other words, the passband bandwidth and steepness need to be balanced so that the left and / or right shoulder steepness of the output signal waveform of filter 100 is related to the bandwidth of resonator 10a. Therefore, when the bandwidth of resonator 10a is adjusted by adjusting the thickness of dielectric layer 12, the left and / or right shoulder steepness can be adjusted. Furthermore, a higher steepness is beneficial for achieving lower insertion loss.

[0070] Furthermore, the insertion loss of filter 100 is related to the electromechanical coupling coefficient K2 of resonator 10a. Therefore, when the electromechanical coupling coefficient K2 of resonator 10a is adjusted by adjusting the thickness of dielectric layer 12, the insertion loss of filter 100 can be adjusted.

[0071] The electromechanical coupling coefficient K2 of the resonator 10b excluding the dielectric layer 12 is usually not adjustable, that is, it is a fixed electromechanical coupling coefficient K2.

[0072] Therefore, the thickness of the dielectric layer 12 can be adjusted according to actual needs, thereby adjusting the electromechanical coupling coefficient K2 of the corresponding resonator 10a, and then adjusting the bandwidth of the resonator 10a, so as to improve the left shoulder steepness and / or right shoulder steepness of the output signal of the filter 100 under the condition of strong suppression near the passband, thereby reducing the insertion loss of the filter 100.

[0073] As shown in Figure 3, the filter 100 may further include a low-velocity layer 14 and a high-velocity layer 15. The low-velocity layer 14 is disposed on the side of the piezoelectric layer 11 facing away from the electrode structure 13. The material of the low-velocity layer 14 may include SiO2, which has a temperature compensation function.

[0074] As shown in Figure 3, the high-velocity layer 15 is disposed on the side of the low-velocity layer 14 facing away from the piezoelectric layer 11. The material of the high-velocity layer 15 may include Si, sapphire, SiC, etc. The sound velocity of the high-velocity layer 15 may be higher than that of the low-velocity layer 14.

[0075] As shown in Figure 3, the filter 100 may further include a temperature compensation layer 16 and a protective layer 17. The temperature compensation layer 16 is disposed on the first surface 111 of the piezoelectric layer 11 and surrounds the electrode structure 13. The protective layer 17 is disposed on the side of the temperature compensation layer 16 facing away from the electrode structure 13. The temperature compensation layer 16 also has a temperature compensation function. The protective layer 17 has a protective function.

[0076] The structure of filter 100 will be described below using the trapezoidal surface acoustic wave filter shown in Figure 4 as an example. As shown in Figure 4, filter 100 has an input terminal IN, an output terminal OUT, and multiple resonators 10.

[0077] For example, the multiple resonators 10 may include multiple resonators S and multiple resonators P. As shown in Figure 3, the number of resonators S is greater than or equal to two, and they are connected in series between the input terminal IN and the output terminal OUT of the filter 100. It can also be understood that the multiple resonators S are located in the series branch, therefore, the resonators S can also be called series resonators S.

[0078] Specifically, as shown in Figure 4, the multiple series resonators S may include series resonator S1, series resonator S2, series resonator S3, and series resonator S4. Series resonators S1, S2, and S3 are connected in series sequentially between the input terminal IN and the output terminal OUT. For example, one end of series resonator S1 is connected to the input terminal IN, the other end of series resonator S1 is connected to one end of resonator S2, the other end of series resonator S2 is connected to one end of series resonator S3, the other end of series resonator S3 is connected to one end of series resonator S4, and the other end of series resonator S4 is connected to the output terminal OUT.

[0079] As shown in Figure 4, multiple resonators P are located in parallel branches; therefore, resonators P can also be called parallel resonators P. One end of parallel resonator P1 is connected to the other end of series resonator S1, and the other end of parallel resonator P1 is connected to ground GND. One end of parallel resonator P2 is connected to the other end of series resonator S2, and the other end of parallel resonator P2 is connected to ground GND. One end of parallel resonator P3 is connected to the other end of series resonator S3, and the other end of parallel resonator P3 is connected to ground GND.

[0080] Multiple resonators 10 can be arranged along the X-axis, along the Y-axis, in multiple rows, or in a rectangular array, etc. The following explanation uses the arrangement of multiple resonators 10 in multiple rows as an example. Specifically, as shown in Figure 5, multiple series resonators S are arranged sequentially along the X-axis, multiple parallel resonators P are arranged along the X-axis, and the series resonators S and parallel resonators P are arranged along the Y-axis.

[0081] As shown in Figure 5, the number of electrode structures 13 in filter 100 is the same as the number of filters 10 in Figure 4. Since Figure 4 includes 7 resonators 10, filter 100 in Figure 5 also includes 7 electrode structures 13.

[0082] As shown in Figure 5, the plurality of electrode structures 13 include at least two electrode structures 13a (first electrode structures) and at least two electrode structures 13b (second electrode structures). Exemplarily, in this embodiment, the plurality of electrode structures 13 includes four electrode structures 13a and three electrode structures 13b.

[0083] At least two electrode structures 13a are connected in series between the input terminal IN and the output terminal OUT of the filter 100 shown in Figure 4. As shown in Figure 5, each electrode structure 13a and the structure below it can form a series resonator S. Therefore, at least two electrode structures 13a and the structure below them can form at least two series resonators S. For example, as shown in Figure 4, four electrode structures 13a and the structure below them can form four series resonators S.

[0084] One end of each electrode structure 13b is connected to one end of the series resonator S of the filter 100 shown in FIG. 4, and the other end of the electrode structure 13b is connected to the ground terminal GND shown in FIG. 4. As shown in FIG. 5, each electrode structure 13b and the structure below it can form a parallel resonator P. Therefore, at least two electrode structures 13b and the structure below them can form at least two parallel resonators P. For example, as shown in FIG. 4, three electrode structures 13b and the structure below them can form three parallel resonators P shown in FIG. 4.

[0085] In one possible implementation, as shown in FIG5, at least one electrode structure 13a is disposed on the dielectric layer 12, and each electrode structure 13b is disposed on the piezoelectric layer 11. That is, at least one of the series resonators S includes the dielectric layer 12. Each parallel resonator P does not include the dielectric layer 12, i.e., the parallel resonators P1, P2, and P3 shown in FIG4 do not include the dielectric layer 12. Thus, when there is a strong suppression requirement near the right shoulder of the passband, the electromechanical coupling coefficient K2 of at least one series resonator S can be adjusted, thereby improving the right shoulder steepness of the output signal of the filter 100.

[0086] In one example, a portion of the electrode structure 13a is disposed on the dielectric layer 12, and the remaining portion of the electrode structure 13a is disposed on the piezoelectric layer 11.

[0087] For example, as shown in Figure 6, one electrode structure 13a is disposed on the dielectric layer 12, and the other three electrode structures 13a are disposed on the second region 1112 of the piezoelectric layer 11. That is, one series resonator S in Figure 4 includes the dielectric layer 12, while the other three series resonators S do not include the dielectric layer 12. Specifically, in Figure 4, series resonator S1 includes the dielectric layer 12, while series resonators S2, S3, and S4 do not include the dielectric layer 12. Or, in Figure 4, series resonator S2 includes the dielectric layer 12, while series resonators S1, S3, and S4 do not include the dielectric layer 12. In Figure 4, series resonator S3 includes the dielectric layer 12, while series resonators S1, S2, and S4 do not include the dielectric layer 12. In Figure 4, series resonator S4 includes the dielectric layer 12, while series resonators S1, S2, and S3 do not include the dielectric layer 12.

[0088] For example, as shown in Figure 7, the first surface 111 includes two first regions 1113, and the filter 100 includes two dielectric layers 12, which are respectively disposed on the two first regions 1113. Two electrode structures 13a are respectively disposed on the two dielectric layers 12, and the remaining two electrode structures 13a are disposed on the piezoelectric layer 11. That is, the two series resonators S in Figure 4 include the dielectric layer 12, while the other two series resonators S do not include the dielectric layer 12. Specifically, series resonators S1 and S2 in Figure 4 both include the dielectric layer 12, while series resonators S3 and S4 do not include the dielectric layer 12. Or, series resonators S1 and S3 in Figure 4 both include the dielectric layer 12, while series resonators S2 and S4 do not include the dielectric layer 12. Or, series resonators S1 and S4 in Figure 4 both include the dielectric layer 12, while series resonators S2 and S3 do not include the dielectric layer 12. Alternatively, in Figure 4, series resonators S2 and S3 both include the dielectric layer 12, while series resonators S1 and S4 do not.

[0089] For example, as shown in Figure 8, the first surface 111 includes three first regions 1113, and the filter includes three dielectric layers 12, which are respectively disposed on the three first regions 1113. Three electrode structures 13a are respectively disposed on the three dielectric layers 12, and the remaining electrode structure 13a is disposed on the piezoelectric layer 11. That is, all three series resonators S in Figure 3 include the dielectric layer 12, while the remaining series resonator S does not. Specifically, series resonators S1, S2, and S3 in Figure 3 all include the dielectric layer 12, while series resonator S4 does not. Alternatively, series resonators S1, S2, and S4 in Figure 3 all include the dielectric layer 12, while series resonator S3 does not. Or, series resonators S2, S3, and S4 in Figure 3 all include the dielectric layer 12, while series resonator S1 does not.

[0090] In another example, as shown in Figure 9, the number of dielectric layers 12 in filter 100 is the same as the number of electrode structures 13a, and each electrode structure 13a is disposed on each dielectric layer 12. That is, all four series resonators S in Figure 4 include dielectric layers 12. Specifically, series resonators S1, S2, S3, and S4 in Figure 4 all have dielectric layers 12.

[0091] When at least two series resonators S include a dielectric layer 12, the electromechanical coupling coefficient K2 of the at least two series resonators S can be adjusted by adjusting the thickness of the at least two dielectric layers 12. Therefore, in this embodiment, the number of series resonators S with adjustable electromechanical coupling coefficient K2 is greater, thereby increasing the degree of freedom in improving the steepness of the right shoulder.

[0092] Furthermore, when at least two series resonators S include a dielectric layer 12, regarding the relationship between the thicknesses of the dielectric layers 12 in the at least two series resonators S, in one example, as shown in FIG9, the thickness d of the dielectric layers 12 in the at least two series resonators S is the same. Therefore, when fabricating the filter 100, the dielectric layers 12 of at least two series resonators S can be fabricated in the same process. This simplifies the fabrication process of the filter 100, thereby improving manufacturing efficiency and reducing costs.

[0093] In another example, as shown in Figure 10, the thickness of the dielectric layer 12 in at least two series resonators S is different. For example, the thickness d1 of series resonator S1, the thickness d2 of series resonator S2, the thickness d3 of series resonator S3, and the thickness d4 of series resonator S4 are all different. As a result, the electromechanical coupling coefficient K2 of each series resonator S is different, thereby increasing the degree of freedom for raising the right shoulder steepness.

[0094] In another example, as shown in Figure 11, the dielectric layer 12 in some series resonators S has the same thickness, while the dielectric layer 12 in some series resonators S has different thicknesses. For example, the thickness d1 of series resonator S1 is the same as the thickness d3 of series resonator S3, the thickness d2 of series resonator S2 is the same as the thickness d4 of series resonator S4, and the thickness d1 of series resonator S1 is different from the thickness d2 of series resonator S2.

[0095] In another possible implementation, as shown in FIG12, each electrode structure 13a is disposed on the piezoelectric layer 11, and at least one electrode structure 13b is disposed on the dielectric layer 12. That is, each series resonator S in FIG4 does not include the dielectric layer 12, i.e., the series resonators S1, S2, and S3 in FIG4 do not include the dielectric layer 12. At least one of the multiple parallel resonators P in FIG4 includes the dielectric layer 12. Thus, when there is a strong suppression requirement near the left shoulder of the passband, the electromechanical coupling coefficient K2 of at least one parallel resonator P can be adjusted, thereby improving the right shoulder steepness of the output signal of the filter 100.

[0096] In one example, a portion of the electrode structure 13b is disposed on the dielectric layer 12, and the remaining portion of the electrode structure 13b is disposed on the piezoelectric layer 11.

[0097] For example, one electrode structure 13b is disposed on the dielectric layer 12, and the other two electrode structures 13b are disposed on the piezoelectric layer 11. That is, one of the parallel resonators P in Figure 4 includes the dielectric layer 12, while the other two parallel resonators P do not include the dielectric layer 12. Specifically, parallel resonator P1 in Figure 4 includes the dielectric layer 12, while parallel resonators P2 and S3 do not include the dielectric layer 12. Alternatively, parallel resonator P2 in Figure 4 includes the dielectric layer 12, while parallel resonators P1 and S3 do not include the dielectric layer 12. Parallel resonator P3 in Figure 4 includes the dielectric layer 12, while parallel resonators P1 and S2 do not include the dielectric layer 12.

[0098] For example, the filter includes two dielectric layers 12, two electrode structures 13b respectively disposed on the two dielectric layers 12, and a remaining electrode structure 13b disposed on the piezoelectric layer 11. That is, the two parallel resonators P in Figure 4 include the dielectric layer 12, while the remaining parallel resonator P does not include the dielectric layer 12. Specifically, parallel resonators P1 and P2 in Figure 4 both include the dielectric layer 12, while parallel resonator P3 does not include the dielectric layer 12. Alternatively, parallel resonators P1 and P3 in Figure 4 both include the dielectric layer 12, while parallel resonator P2 does not include the dielectric layer 12. Alternatively, parallel resonators P2 and P3 in Figure 4 both include the dielectric layer 12, while parallel resonator P1 does not include the dielectric layer 12.

[0099] In another example, the number of dielectric layers 12 in filter 100 is the same as the number of electrode structures 13b, and each electrode structure 13b is disposed on three dielectric layers 12. That is, all three parallel resonators P in Figure 4 include dielectric layers 12. Specifically, parallel resonators P1, P2, and P3 in Figure 4 all include dielectric layers 12.

[0100] When at least two parallel resonators P include a dielectric layer 12, the electromechanical coupling coefficient K2 of the at least two parallel resonators P can be adjusted by adjusting the thickness of the at least two dielectric layers 12. Therefore, in this embodiment, the number of parallel resonators P with adjustable electromechanical coupling coefficient K2 is greater, thereby increasing the degree of freedom in improving the steepness of the right shoulder.

[0101] Furthermore, when at least two parallel resonators P include a dielectric layer 12, regarding the relationship between the thicknesses of the dielectric layers 12 in the at least two parallel resonators P, in one example, the thickness d of the dielectric layers 12 in the at least two parallel resonators P is the same. Therefore, when manufacturing the filter 100, the first dielectric layers 12 of the at least two parallel resonators P can be fabricated in the same process. This simplifies the fabrication process of the filter 100, thereby improving manufacturing efficiency and reducing costs.

[0102] In another example, the thickness of the dielectric layer 12 in at least two parallel resonators P is different. For example, the thickness d1 of parallel resonator P1, the thickness d2 of parallel resonator P2, and the thickness d3 of parallel resonator P3 are all different. As a result, the electromechanical coupling coefficient K2 of each parallel resonator P is different, thereby increasing the degree of freedom for raising the right shoulder steepness.

[0103] In another example, the dielectric layer 12 in some parallel resonators P has the same thickness, while the dielectric layer 12 in some parallel resonators P has different thicknesses. For example, the thickness d1 of parallel resonator P1 is the same as the thickness d3 of parallel resonator P3, but the thickness d1 of parallel resonator P1 is different from the thickness d2 of parallel resonator P2.

[0104] In another possible implementation, as shown in FIG13, the filter includes multiple dielectric layers 12, including a first dielectric layer 12a and a second dielectric layer 12b. At least one electrode structure 13a is disposed on the first dielectric layer 12a, and at least one electrode structure 13b is disposed on the second dielectric layer 12b. That is, at least one series resonator S includes the first dielectric layer 12a, and at least one parallel resonator P includes the second dielectric layer 12b. The number of series resonators S including the first dielectric layer 12a can be one, two, three, or four, and the number of parallel resonators P including the second dielectric layer 12b can be one, two, or three. Specific implementation details can be found in the foregoing embodiments and will not be repeated here.

[0105] As shown in Figure 14, the thickness d of the first dielectric layer 12a in the series resonator S is... S The thickness d of the second dielectric layer 12b in the parallel resonator P K The difference is that the thickness d of the first dielectric layer 12a in the series resonator S is different. S Adjust its electromechanical coupling coefficient K2, and through the thickness d of the second dielectric layer 12b in the parallel resonator P. K By adjusting its electromechanical coupling coefficient K2, the electromechanical coupling coefficient K2 of the series resonator S is made different from that of the parallel resonator P, thereby achieving different steepness on both sides of the passband of filter 100.

[0106] The simulation results for the filter 100 in the related technology and the filter 100 shown in Figure 12 are presented below. Since each resonator in the filter 100 of the related technology includes a piezoelectric layer 11 and an electrode structure 13, but does not include a dielectric layer 12, the electromechanical coupling coefficient K2 of each resonator S / P is the same. In the filter 100 of this embodiment, each parallel resonator (P1, P2, and P3) does not include a dielectric layer 12. Therefore, the electromechanical coupling coefficient K2 of each parallel resonator P is the same as that of each resonator in the related technology. Each series resonator (S1, S2, S3, and S4) includes a dielectric layer 12. Therefore, by adjusting the thickness of the dielectric layer 12 of the series resonator S, the electromechanical coupling coefficient K2 of the series resonator S can be adjusted to 9%, which is less than the electromechanical coupling coefficient K2 of the parallel resonator P. The three quality factor parameters (Qr, Qa, and Qmax) of the related technology are also the same as the three quality factor parameters (Qr, Qa, and Qmax) of this embodiment. Refer to Table 1 for specific parameters.

[0107] Table 1 shows the relevant parameters of filter 100 in related technologies and filter 100 in this embodiment.

[0108] After simulation experiments, the insertion loss curves shown in Figures 15 and 16 can be obtained. The horizontal axis represents frequency, the left vertical axis represents insertion loss, and the right vertical axis also represents insertion loss. Figure 16 is a partially enlarged schematic diagram of the insertion loss curve shown in Figure 15. In Figures 15 and 16, the dashed line is the insertion loss curve of the filter 100 of the related technology, and the solid line is the insertion loss curve of the filter 100 shown in Figure 12.

[0109] Comparing the solid and dashed lines in Figure 15, it can be seen that the passband center difference between the related technology and the embodiment shown in Figure 12 is almost identical. Furthermore, combining Figures 15 and 16, at 915MHz, the insertion loss curve of this embodiment shows -1.21dB for the embodiment shown in Figure 12 and -1.72dB for the related technology. The insertion loss at point A is the same for both the related technology and the embodiment shown in Figure 12. When the insertion loss of the related technology decreases from -1.72dB to point A, and the insertion loss of the embodiment shown in Figure 12 decreases from -1.21dB to point A, the reduction in insertion loss in the embodiment shown in Figure 12 is greater, resulting in a steeper right shoulder.

[0110] Furthermore, referring to Figures 15 and 16, the insertion loss curve of this embodiment at 915MHz shows that the insertion loss of the embodiment shown in Figure 12 is -1.21dB, while the insertion loss of related technologies is -1.72dB. Therefore, compared with related technologies, the insertion loss of the embodiment shown in Figure 12 is lower. In other words, the embodiments of this application can reduce the insertion loss of filter 100.

[0111] In other embodiments of this application, the difference from the embodiment shown in FIG1 lies in the structure of the filter 200. Specifically, in this embodiment, the filter 200 may be a DMS type filter. As shown in FIG17 and FIG18, the DMS type filter may include: a piezoelectric layer 11, a dielectric layer 12, and multiple electrode structures 13. The multiple electrode structures 13 include at least two first electrode structures 133 and at least two reflective gratings 134. Exemplarily, in this embodiment, the DMS type filter may include three first electrode structures 133 and two reflective gratings 134.

[0112] As shown in Figure 19, one end of the first electrode structure 133a is connected to the ground terminal GND, and the other end is connected to the output terminal OUT of the filter 200. One end of the first electrode structure 133b is connected to the input terminal IN of the filter 200, and the other end is connected to the ground terminal GND. One end of the first electrode structure 133c is connected to the ground terminal GND, and the other end is connected to the output terminal OUT of the filter 200. Two reflective gratings 134 are located on both sides of the plurality of transducer units 133.

[0113] In one possible implementation, as shown in FIG18, at least one first electrode structure 133 is disposed on the dielectric layer 12, and the reflective grating 134 is disposed on the piezoelectric layer 11. For example, one first electrode structure 133 is disposed on the dielectric layer 12, and the other two first electrode structures 133 are disposed on the piezoelectric layer 11. Alternatively, the first surface 111 includes two first regions 1113 (not shown in FIG18), the filter 200 includes two dielectric layers 12, the two dielectric layers 12 are respectively disposed on the two first regions 1113, the two first electrode structures 133 are respectively disposed on the dielectric layers 12, and the other first electrode structure 133 is disposed on the piezoelectric layer 11. Alternatively, the first surface 111 includes three first regions 1113, the filter 200 includes three dielectric layers 12, the three dielectric layers 12 are respectively disposed on the three first regions 1113, and the three first electrode structures 133 are respectively disposed on the three dielectric layers 12.

[0114] As shown in Figure 18, the first electrode structure 133 and the structure below it can form a transducer unit (IDT) 10. Specifically, the first electrode structure 133 can be an interdigital transducer (IDT). Therefore, by adjusting the thickness of at least one dielectric layer 12, the electromechanical coupling coefficient K2 of at least one transducer unit 10 can be adjusted, thereby improving the right and left shoulder steepness of the signal appearing in the filter 200.

[0115] In another possible implementation, as shown in FIG20, the first electrode structures 133 are all disposed on the piezoelectric layer 11, and at least one reflective grating 134 is disposed on the dielectric layer 12. For example, one reflective grating 134 is disposed on the dielectric layer 12 and one reflective grating 134 is disposed on the piezoelectric layer 11. Alternatively, the filter 200 includes two dielectric layers 12, and two reflective gratings 134 are respectively disposed on the dielectric layers 12.

[0116] In another possible implementation, as shown in FIG21, the first surface 111 includes a plurality of first regions 1113, and the filter 200 includes a plurality of dielectric layers 12, which are respectively disposed on the plurality of first regions 1113. The plurality of dielectric layers 12 include dielectric layer 12a and dielectric layer 12b, at least one first electrode structure 133 is disposed on dielectric layer 12a, and at least one reflective gate 134 is disposed on dielectric layer 12b. Furthermore, the dielectric layers 12a and 12b have different thicknesses.

[0117] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A filter, characterized in that, include: A piezoelectric layer having a first surface, the first surface including a spaced first region and a second region; A dielectric layer is disposed on the first region; Multiple electrode structures, at least one of the electrode structures is disposed on the dielectric layer, and at least one of the electrode structures is disposed on the second region.

2. The filter according to claim 1, characterized in that, The plurality of electrode structures include at least two first electrode structures, which are connected in series between the input terminal and the output terminal of the filter, and at least one first electrode structure is disposed on the dielectric layer.

3. The filter according to claim 2, characterized in that, The first surface includes a plurality of spaced first regions, and the filter includes a plurality of dielectric layers respectively disposed in the plurality of first regions, wherein the plurality of dielectric layers includes at least two first dielectric layers; At least two of the first electrode structures are respectively disposed on the at least two first dielectric layers.

4. The filter of claim 3, wherein, The thicknesses of the at least two first dielectric layers are either the same or different.

5. The filter according to any one of claims 2-4, characterized in that, The plurality of electrode structures further includes at least two second electrode structures, one end of the second electrode structure being connected to one end of the first electrode structure, and the other end of the second electrode structure being connected to a ground terminal. At least one second electrode structure is disposed on the dielectric layer.

6. The filter of claim 5, wherein, The filter includes a plurality of dielectric layers respectively disposed in a plurality of first regions, and the plurality of dielectric layers includes at least two second dielectric layers; At least two second electrode structures are respectively disposed on the at least two second dielectric layers.

7. The filter of claim 6, wherein, The thicknesses of the at least two second dielectric layers are either the same or different.

8. The filter according to any one of claims 1-7, characterized in that, The plurality of electrode structures include at least two first electrode structures and at least two second electrode structures. The two ends of the first electrode structure are electrically connected to the input terminal and the output terminal of the filter, respectively. One end of the second electrode structure is connected to one end of the first electrode structure, and the other end of the second electrode structure is connected to the ground terminal. The filter includes a plurality of dielectric layers disposed in a plurality of first regions, the plurality of dielectric layers including a first dielectric layer and a second dielectric layer, at least one first electrode structure disposed on the first dielectric layer, at least one second electrode structure disposed on the second dielectric layer, and the thickness of the first dielectric layer is different from the thickness of the second dielectric layer.

9. The filter according to any one of claims 1-8, characterized in that, The filter includes a trapezoidal surface acoustic wave filter.

10. The filter of claim 1, wherein, The plurality of electrode structures include at least two first electrode structures and at least two reflective gratings, wherein at least one first electrode structure is disposed on the dielectric layer, and / or at least one reflective grating is disposed on the dielectric layer.

11. The filter according to claim 10, characterized in that, The filter includes a dual-mode surface acoustic wave (DMS) filter.

12. A communications device, characterized by It includes a power amplifier and a filter as described in any one of claims 1-11, wherein the power amplifier is electrically connected to the filter.

13. An electronic device, comprising: It includes a circuit board and the communication device of claim 12, wherein the communication device is disposed on the circuit board.

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