WO2023123465A1

WO2023123465A1 - Filter, radio frequency system, and electronic device

Info

Publication number: WO2023123465A1
Application number: PCT/CN2021/143938
Authority: WO
Inventors: 鲍景富; 吴婷; 李伍平; 黄裕霖; 李昕熠; 高宗智
Original assignee: 华为技术有限公司
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2023-07-06
Also published as: CN116941184A

Abstract

The present disclosure relates to a filter, a radio frequency system, and an electronic device. The filter generally comprises two resonators arranged up and down and a first coupling layer located between the two resonators. Each resonator comprises two electrodes arranged up and down and a piezoelectric layer located between the two electrodes. In the filter, at least one resonator comprises a material having an electromechanical coupling coefficient of not less than 20%. The solution can reasonably regulate and control the coupling strength between resonators of a filter, so that it is ensured that the filter has good filtering performance in a high-frequency range.

Description

Filters, RF Systems and Electronics

technical field

The present disclosure relates to the field of communications, and more particularly to filters, radio frequency systems, and electronic devices.

Background technique

In the field of communication, the acoustic filter is an important component, which can be used in the transmission path of the signal, and use the acoustic principle to filter the signal in transmission, so as to select the signal of the appropriate frequency. Acoustic filters have a wide range of applications, such as in various mobile devices, vehicle communication devices, and the like. Acoustic filters are one of the core components in current RF modules.

With the in-depth advancement of mobile communication technology, this poses a higher challenge to the technical requirements of the filter. The conventional acoustic filter uses aluminum nitride as the medium, and an external signal is applied at the input end. Based on the piezoelectric effect, the electrical signal is converted into an acoustic signal and propagated in the medium, and at the output end, the acoustic signal is converted into an electrical signal based on the inverse piezoelectric effect. In order to realize the signal transmission. However, the transmission performance of existing acoustic filters needs to be improved.

Contents of the invention

In view of the above problems, embodiments of the present disclosure provide a filter, a corresponding radio frequency system, and an electronic device for improving the performance of a transmission signal.

In a first aspect of the present disclosure, a filter is provided. The filter includes a first resonator, a second resonator and a first coupling layer, the first resonator includes a first electrode, a second electrode and a first piezoelectric layer, and the first piezoelectric layer is arranged on the first between the electrode and the second electrode; the second resonator includes a third electrode, a fourth electrode and a second piezoelectric layer, the second piezoelectric layer is arranged between the third electrode and the fourth electrode, the The first coupling layer is located between the first resonator and the second resonator, wherein at least one of the first resonator and the second resonator has an electromechanical coupling coefficient not lower than 20%. According to the method of the present disclosure, the first resonator and the second resonator with an electromechanical coupling coefficient of not less than 20% are realized by using a high acoustic coupling medium, and the first resonator and the second resonator are effectively regulated through the structural design or material optimization of the first coupling layer. The coupling strength between the two resonators, the filter thus constructed can realize ultra-large bandwidth in the ultra-high frequency range, so as to meet the communication requirements of larger bandwidth and higher frequency band.

In an implementation manner of the first aspect, the first coupling layer includes a material with an acoustic impedance ranging from 4*10 ⁶ kg/m ² s to 16*10 ⁶ kg/m ² s. In this way, by adjusting the acoustic impedance of the material of the first coupling layer located between the first resonator and the second resonator, the coupling strength can be adjusted reasonably, so as to meet the design requirements of the filter.

In an implementation manner of the first aspect, at least one of the first piezoelectric layer and the second piezoelectric layer includes lithium niobate or lithium tantalate. In this way, high-quality piezoelectric transducing materials can be used to make the electromechanical coupling coefficients of the first resonator and the second resonator meet the design requirements, thereby improving the ultra-large bandwidth performance of the filter under high frequency conditions.

In an implementation manner of the first aspect, the lithium niobate is one or more of X-cut lithium niobate, Y-cut lithium niobate, and -18°Y Y lithium niobate, and the lithium tantalate is X-cut lithium niobate One or more of lithium tantalate, Y-cut lithium tantalate, and -18°Y lithium tantalate. In this way, the modification of the piezoelectric layer with good performance at ultra-large bandwidths can be achieved using materials with suitable cut angles.

In an implementation manner of the first aspect, the first coupling layer includes one or more of SiO ₂ , SiOC, SiOF and W. In this way, the coupling strength of the filter is optimized by improving the material of the first coupling layer between the two resonators.

In an implementation manner of the first aspect, a hole-like structure is provided in the first coupling layer, and the hole-like structure is used to weaken the coupling strength between the first resonator and the second resonator. In this way, the porous structure can change the acoustic impedance of the material of the first coupling layer, so that it meets the design requirement of large bandwidth.

In an implementation manner of the first aspect, the hole structure includes at least one through hole or blind hole, and the at least one through hole penetrates through the first coupling layer. In this way, through the change of the acoustic impedance of the first coupling layer through the through hole or the blind hole, the restriction on the performance of the filter caused by improper coupling strength is avoided.

In an implementation manner of the first aspect, the first resonator further includes at least one first recess, and the at least one first recess extends from a portion of the first piezoelectric layer that is not covered by the first electrode. the first piezoelectric layer. In this way, the confinement of the energy of the resonator and the suppression of other transverse modes are achieved by changing the structure to create the first recess, thereby further optimizing the performance of the filter.

In an implementation manner of the first aspect, the second resonator further includes at least one second recess, and the at least one second recess extends from a part of the second piezoelectric layer that is not covered by the fourth electrode. the second piezoelectric layer. In this way, the structure of the first concave portion and the second concave portion can be changed at the same time through the approximately symmetrical arrangement, so that the filter can achieve a more excellent quality factor and a cleaner spectral response.

In an implementation manner of the first aspect, the filter further includes at least one metal piece configured as the first electrode or the second electrode or the third electrode or the fourth electrode. In this way, the effective suppression of the stray effect of the filter by metal parts can be used, and the filter can have a relatively flat and clean electrical response, which helps to improve the quality factor of the filter, making it applicable to various In mobile communication systems or other radio frequency circuits.

In an implementation manner of the first aspect, the filter further includes a substrate disposed on a side of the second resonator opposite to the first resonator for supporting the first resonator and the second resonator. A resonator, wherein the substrate includes a Bragg reflection layer composed of a multilayer film stack. In this way, the signal leakage can be reduced and the performance of the filter can be improved through the reflection of the sound wave at the interface of each layer of film.

In a second aspect of the present disclosure, a filter is provided. The filter includes a first resonator, a second resonator and a first coupling layer, the first coupling layer is located between the first resonator and the second resonator, and a hole structure is arranged in the first coupling layer , the hole structure is used to weaken the coupling strength between the first resonator and the second resonator. In this way, the porous structure changes the acoustic impedance of the material of the first coupling layer, and through structural improvement, the performance of the filter can be improved.

In an implementation manner of the second aspect, the hole structure includes at least one through hole or blind hole, and the at least one through hole penetrates through the first coupling layer. In this way, the performance of the filter can be improved by adjusting the acoustic impedance of the material of the first coupling layer through the through hole or the blind hole.

In an implementation manner of the second aspect, the first resonator, the first coupling layer, and the second resonator are sequentially stacked along the first direction, and the at least one through hole or blind hole includes a plurality of through holes or For blind holes, the plurality of through holes extend in parallel between the first resonator and the second resonator along a second direction perpendicular to the first direction. In this way, by providing a plurality of through holes or blind holes, the regulation effect of the through holes or blind holes on the material of the first coupling layer can be increased, and the coupling strength can be controlled within a reasonable range in a simple and feasible manner.

In an implementation manner of the second aspect, the first resonator includes a first electrode, a second electrode, a first piezoelectric layer, and at least one first recess, and the first piezoelectric layer is located between the first electrode and the Between the second electrodes, the at least one first recess extends through the first piezoelectric layer from a portion of the first piezoelectric layer not covered by the first electrode. In this way, by setting the first concave part and penetrating the first piezoelectric layer, the first concave part is generated through the change of the structure to realize the energy confinement of the resonator and the suppression of other transverse modes, thereby further improving the energy confinement and The suppression of spurious modes achieves a cleaner and smoother filter frequency response with excellent out-of-band suppression.

In an implementation manner of the second aspect, the second resonator includes a third electrode, a fourth electrode, a second piezoelectric layer, and at least one second recess, and the second piezoelectric layer is located between the third electrode and the Between the fourth electrodes, the at least one second recess extends from a portion of the second piezoelectric layer not covered by the fourth electrode through the second piezoelectric layer. In this way, the energy confinement of the resonator and the suppression of other transverse modes are achieved by changing the structure to create a second concave portion, thereby further improving the energy confinement and suppression of stray modes in the filter, achieving a cleaner, smoother and better Filter frequency response for out-of-band rejection.

In an implementation manner of the second aspect, the at least one first recess extends to sequentially penetrate through the first piezoelectric layer, the second electrode, the first coupling layer, the third electrode, and the second piezoelectric layer and the fourth electrode.

In an implementation manner of the second aspect, the at least one second recess extends to sequentially penetrate through the second piezoelectric layer, the third electrode, the first coupling layer, the second electrode, and the first piezoelectric layer and the first electrode.

In an implementation manner of the second aspect, the filter further includes: at least one metal piece configured as the first electrode or the second electrode or the third electrode or the fourth electrode. In this way, the filter can have a relatively flat and clean electrical response by utilizing the suppressing effect of the metal parts on the stray effect of the filter, thereby improving the quality factor of the filter.

In an implementation manner of the second aspect, the electromechanical coupling coefficient of at least one of the first resonator and the second resonator is not lower than 20%. In this way, the filter can realize ultra-large bandwidth in the ultra-high frequency range, so as to meet the communication requirements of larger bandwidth and higher frequency band.

In an implementation manner of the second aspect, the first coupling layer includes a material with an acoustic impedance ranging from 4*10 ⁶ kg/m ² s to 16*10 ⁶ kg/m ² s. In this way, by adjusting the acoustic impedance of the material of the first coupling layer between the first resonator and the second resonator, the filter can meet the design requirements.

In an implementation of the second aspect, at least one of the first piezoelectric layer and the second piezoelectric layer includes lithium niobate or lithium tantalate. In this way, high-quality piezoelectric transducing materials can be used to improve filter performance at high frequencies to achieve large bandwidths.

In an implementation of the second aspect, the lithium niobate is one or more of X-cut lithium niobate, Y-cut lithium niobate, and -18°Y Y lithium niobate, and the lithium tantalate is X-cut lithium niobate One or more of lithium tantalate, Y-cut lithium tantalate, and -18°Y lithium tantalate. In this way, the modification of the piezoelectric layer with good performance at ultra-large bandwidths can be achieved using materials with suitable cut angles.

In an implementation manner of the second aspect, the first coupling layer includes one or more of SiO ₂ , SiOC, SiOF and W. In this way, the coupling strength of the filter is optimized by improving the material of the first coupling layer between the two resonators.

In an implementation manner of the second aspect, the at least one metal piece forms one or more of the following shapes: polygonal, circular, elliptical, well-shaped, and honeycomb-shaped. In this way, the form of the metal piece can be expanded according to actual needs, thereby expanding its applicable range.

In an implementation manner of the second aspect, the filter further includes: a third resonator arranged in a stacked manner on a side of the second resonator opposite to the first resonator, and a second coupling layer, between the third resonator and the second resonator. In this way, by increasing the number of resonators, more and more flexible ways of adjusting the coupling strength can be provided.

In an implementation manner of the second aspect, each third resonator includes: a fifth electrode; a sixth electrode; and a third piezoelectric layer, and the third piezoelectric layer is disposed on the fifth electrode and the sixth electrode. between the electrodes.

In an implementation manner of the second aspect, the filter further includes a substrate disposed on a side of the second resonator opposite to the first resonator for supporting the first resonator and the second resonator. A resonator, wherein the substrate includes a Bragg reflection layer composed of a multilayer film stack. In this way, the signal leakage can be reduced and the performance of the filter can be improved through the reflection of the sound wave at the interface of each layer of film.

In a third aspect of the present disclosure, a radio frequency system is provided. The radio frequency system includes a filter and a radio frequency circuit according to the first aspect or the second aspect of the present disclosure.

In a fourth aspect of the present disclosure, an electronic device is provided. The electronic device includes a processor, a circuit board, and the filter according to the first aspect or the second aspect of the present disclosure, wherein the filter and the processor are arranged on the circuit board.

It should be understood that what is described in the Summary of the Invention is not intended to define key or important features of implementations of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will be readily understood through the following description.

Description of drawings

The above and other features, advantages and aspects of the various embodiments of the present disclosure will become more apparent with reference to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, identical or similar reference numerals denote identical or similar elements, wherein:

Fig. 1 shows a schematic cross-sectional view of a filter according to an exemplary embodiment of the present disclosure, in which a feasible wiring mode is schematically shown;

Figure 2A shows a filter with symmetric modes according to an exemplary embodiment of the present disclosure;

Figure 2B shows a filter with anti-symmetric modes according to an exemplary embodiment of the present disclosure;

FIG. 3 is an admittance curve diagram used to describe the implementation principle of the present disclosure;

Fig. 4 shows a schematic perspective view of a filter according to another exemplary embodiment of the present disclosure;

Fig. 5 shows a schematic cross-sectional view of a filter according to another exemplary embodiment of the present disclosure;

Fig. 6 shows a schematic perspective view of a filter according to another exemplary embodiment of the present disclosure;

Fig. 7 shows a schematic cross-sectional view of a filter according to another exemplary embodiment of the present disclosure;

Fig. 8 shows a schematic perspective view of a filter according to yet another exemplary embodiment of the present disclosure;

Figure 9 shows a graph of the admittance of the filter in Figure 8;

Fig. 10 shows a schematic perspective view of a filter according to yet another exemplary embodiment of the present disclosure;

Fig. 11 shows the admittance curve graph of the filter in Fig. 10;

Fig. 12 shows a schematic perspective view of a filter according to yet another exemplary embodiment of the present disclosure;

Fig. 13 shows a schematic perspective view of a filter according to yet another exemplary embodiment of the present disclosure;

Fig. 14 shows a schematic perspective view of a filter set composed of a plurality of unit filters according to an embodiment of the present disclosure;

Fig. 15 shows a schematic cross-sectional view of a filter set composed of a plurality of unit filters according to an embodiment of the present disclosure;

Fig. 16 shows a schematic top view of a filter set composed of a plurality of unit filters according to an embodiment of the present disclosure; and

17 shows a schematic diagram of an example wireless communication system in which embodiments according to the present disclosure may be implemented.

Detailed ways

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the drawings, it should be understood that the disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein; A more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for exemplary purposes only, and are not intended to limit the protection scope of the present disclosure.

In the description of the embodiments of the present disclosure, the term "comprising" and its similar expressions should be interpreted as an open inclusion, that is, "including but not limited to". The term "based on" should be understood as "based at least in part on". The terms "one embodiment" or "the embodiment" should be read as "at least one embodiment". The terms "first", "second", etc. may refer to different or the same object. The term "and/or" means at least one of the two items associated with it. For example "A and/or B" means A, B, or A and B. Other definitions, both express and implied, may also be included below.

It should be understood that for the technical solutions provided by the embodiments of the present application, in the introduction of the following specific embodiments, some repetitions may not be repeated, but it should be considered that these specific embodiments have been referred to each other and can be combined with each other.

As discussed above, the filter can filter the signal frequency, how to expand the bandwidth of the filter in the high frequency band is a problem that designers expect to solve. According to some embodiments of the present disclosure, the coupling strength between modes in the filter can be regulated by adjusting the material of the internal structure of the filter. It is also possible to improve the internal structure of the filter, such as using through holes or blind holes to change the coupling strength between modes, so that the filter can achieve an increase in bandwidth in the ultra-high frequency range.

The overall improvement principle of the filter of the embodiment of the present disclosure will be described below with reference to FIGS. 1 to 3 . Fig. 1 shows a schematic cross-sectional view of a filter 100 according to an exemplary embodiment of the present disclosure, in which a possible wiring mode is schematically shown. As shown in FIG. 1 , a filter 100 is coupled between an input terminal IN and an output terminal OUT. When an external signal of the same polarity is applied to the filter 100, the filter excites a symmetrical mode. When an external signal of opposite polarity is applied to the filter 100, the filter excites an antisymmetric mode.

2A and 2B illustrate a filter 200 with symmetric and anti-symmetric modes, respectively, according to an exemplary embodiment of the present disclosure. As shown in FIG. 2A and FIG. 2B , the two

middle electrodes

212 and 221 of the filter 200 are coupled to the reference terminal REF, and the upper electrode 211 and the lower electrode 222 are connected to an external signal. When the signals applied to the upper electrode 211 and the lower electrode 222 are of the same polarity, as shown in FIG. 2A , the filter 200 excites a symmetrical mode. When the signals applied to the upper electrode 211 and the lower electrode 222 are of opposite polarities, as shown in FIG. 2B , the filter 200 excites an antisymmetric mode.

FIG. 3 shows an admittance curve diagram of the realization principle of the present disclosure, which can be obtained by testing the filter 100 in FIG. 1 or the filter 200 in FIGS. 2A and 2B . In FIG. 3 , the abscissa represents the frequency value of the signal in the

filter

100 or 200 , and the ordinate represents the admittance of the signal. Admittance can be defined as the reciprocal of impedance. Through experiments or computer simulation methods, two modal curves can be obtained in the admittance diagram of FIG. 3 , wherein there is a certain gap in frequency between the valley T of curve I and the peak P of curve II. According to the design principle of the filter, it is necessary to make the anti-resonant frequency of the symmetrical mode close to the resonant frequency of the anti-symmetrical mode, or make the anti-resonant frequency of the anti-symmetrical mode close to the resonant frequency of the symmetrical mode. On the one hand, if the coupling strength between the symmetric mode and the antisymmetric mode is very strong, there will be a great repulsion between the two, which will result in a large frequency gap between the modes, thus As a result, there are pits in the constructed filter band, and the flatness design requirements of the filter cannot be met. On the other hand, if the coupling strength between the symmetric mode and the antisymmetric mode is greatly weakened, it will cause the antiresonance frequency of the symmetric mode to be much higher than the resonant frequency of the antisymmetric mode, or cause the The anti-resonance frequency is much higher than the resonance frequency of the symmetrical mode. This over-coupling will lead to a decrease in bandwidth, which is not conducive to broadband applications. It will be appreciated that the modes of vibration described herein can be a variety of bulk acoustic waves. For example, it may be a longitudinal shear bulk acoustic wave, a longitudinal stretch bulk acoustic wave, a Lamb wave, and the like. The specific form of the bulk acoustic wave is not limited by the embodiments of the present disclosure.

In the admittance curve in Figure 3, if the gap between the two curves I and II is smaller, it means that the coupling strength between the two is more reasonable, and the performance of the filter is better. The study found that by changing the structure and material of the internal components of the filter, the coupling strength between the two modes can be adjusted, thereby improving the filtering performance of the filter. Therefore, in some embodiments of the present disclosure, the coupling strength between the modes of the filter can be adjusted to meet the design principles, so as to construct a filter that satisfies broadband, high frequency, low in-band insertion loss, and high flatness. device.

Schematic diagrams of filters according to some exemplary embodiments of the present disclosure are described below with reference to FIGS. 4 to 13 . Fig. 4 shows a schematic perspective view of a filter 400 according to another exemplary embodiment of the present disclosure. As shown in FIG. 1 and FIG. 4 , the filter 400 generally includes a first resonator 410 , a second resonator 420 and a first coupling layer 430 located between the first resonator 410 and the second resonator 420 . The first resonator 410 includes a first electrode 411 , a second electrode 412 and a first piezoelectric layer 413 disposed between the first electrode 411 and the second electrode 412 . The second resonator 420 includes a third electrode 421 , a fourth electrode 422 and a second piezoelectric layer 423 disposed between the third electrode 421 and the fourth electrode 422 .

In some embodiments, the filter 400 can be optimized by adjusting the electromechanical coupling coefficient k ² of the first resonator 410 or the second resonator 420 . The electromechanical coupling coefficient ^k2 is used to measure the degree of mutual conversion between mechanical energy and electrical energy of the resonator during the vibration process, which can be defined by the following formula:

where _fr represents the resonant frequency of the material and f _a represents the antiresonant frequency of the material.

In some embodiments, the first resonator 410 includes a high-coupling piezoelectric material such that its electromechanical coupling coefficient k ² is not lower than 20%. For example, the piezoelectric material 313 of the first resonator 410 is made of lithium niobate (Lithium Niobate , LiNbO ₃ ) or lithium tantalate (Lithium Tantalate, LiTaO ₃ ). In some other embodiments, the second resonator 420 includes a high-coupling piezoelectric material, so that its electromechanical coupling coefficient is not lower than 20%, for example, the piezoelectric layer 423 of the second resonator 420 is made of lithium niobate or lithium tantalate production.

In a further embodiment, both the first resonator 410 and the second resonator 420 achieve an electromechanical coupling coefficient not lower than 20%, for example, both the first piezoelectric layer 413 and the second piezoelectric layer 423 are made of niobium Lithium Oxide or Lithium Tantalate.

In some embodiments, the electromechanical coupling coefficient k ² of the first resonator 410 or the second resonator 420 is not lower than 20%. In this case, curves I and II in FIG. 3 can achieve a large bandwidth. Therefore, the filter 400 has good performance over a larger frequency width, so it is suitable for the design of broadband filters.

In some embodiments, the lithium niobate may be lithium niobate with a Y-cut angle of -18°. It should be understood that the specific angles here are only exemplary rather than restrictive. Lithium niobate with other cutting angles can also be used, for example, any cutting angle within the range of -10°Y cutting angle to -30°Y cutting angle. In other embodiments, an X-cut lithium niobate whose cutting angle is in the X direction or a Y-cut lithium niobate whose cutting angle is in the Y direction may also be used. It should also be understood that the X-cut lithium niobate or the Y-cut lithium niobate is not strictly required to be along the X direction or the Y direction. In other embodiments, lithium niobate with any cutting angle within the range of -10°X cutting angle to 10°X cutting angle can be used, or any cutting angle within the range of -10°Y cutting angle to 10°Y cutting angle can be used. Lithium niobate with cut corners.

In some embodiments, the lithium tantalate may be lithium tantalate with a -18°Y cut angle. It should be understood that the specific angles here are only exemplary rather than restrictive. Lithium tantalate with other cut angles can also be used, for example, any cut angle within the range of -10°Y cut angle to -30°Y cut angle. In other embodiments, an X-cut lithium tantalate whose cutting angle is in the X direction or a Y-cut lithium tantalate whose cutting angle is in the Y direction may also be used. It should also be understood that the X-cut lithium tantalate or the Y-cut lithium tantalate is not strictly required to be along the X direction or the Y direction. In other embodiments, lithium tantalate with any cutting angle within the range of -10°X cutting angle to 10°X cutting angle can be used, or any cutting angle within the range of -10°Y cutting angle to 10°Y cutting angle can be used. Lithium tantalate with cut corners.

In this way, the material with the appropriate cutting angle can be determined through experiments or simulation calculations, so that the most suitable material can be selected to improve the piezoelectric layer. By improving the electromechanical coupling coefficient k ² , the filter can have a large bandwidth. good performance.

Referring back to FIG. 1 , as shown, when the filter 100 is tested, the first electrode 111 of the filter 100 is coupled to the input IN and the output OUT The fourth electrode 122 of the filter 100 is coupled to the output Terminal OUT, and both the second electrode 112 and the third electrode 121 are coupled to the reference terminal REF. It should be understood that the connection manner shown here is only illustrative and not restrictive. According to specific usage scenarios, other wiring methods can be used to apply external signals to the filter 100 .

In a further embodiment, as shown in FIG. 4 , at least one of the first piezoelectric layer 413 and the second piezoelectric layer 423 of the filter 400 may include lithium niobate or lithium tantalate. In this way, the performance of the filter 400 can be optimized by improving the materials of the first piezoelectric layer 413 and the second piezoelectric layer 423 .

In some embodiments, the acoustic impedance Z of the material of the first coupling layer 430 can be adjusted, so as to reasonably reduce the coupling strength between the symmetric mode and the anti-symmetric mode. Acoustic impedance Z is used to measure the resistance to be overcome to displace the medium, which can be defined by the following formula.

Z=v*ρ

Wherein, v represents the velocity of sound waves propagating in the material of the first coupling layer 430 , and ρ represents the density of the material of the first coupling layer 430 .

In some embodiments, the first coupling layer 430 may include a material with an acoustic impedance Z ranging from 4*10 ⁶ kg/m ² s to 16*10 ⁶ kg/m ² s. In this way, reasonable control of the coupling strength between the first resonator 410 and the second resonator 420 can be achieved by making the acoustic impedance Z within the above range.

In a further embodiment, the first coupling layer 330 may include SiO ₂ (Silicon dioxide, silicon dioxide), SiOC (Carbon-doped silicon dioxide, carbon-doped silicon dioxide), SiOF (Fluorine-doped silicon dioxide, fluorine-doped silica), W (Tungsten, tungsten) or any combination of these materials. Of course, it should be understood that the materials of the first coupling layer 430 listed here are only exemplary, not limiting. The first coupling layer 430 can be made of other materials as long as its acoustic impedance Z can be between 4*10 ⁶ kg/m ² s and 16*10 ⁶ kg/m ² s. The specific material is not limited by the embodiments of the present disclosure.

Research has found that, in addition to directly improving the material of the first coupling layer 430 of the filter 400 , the acoustic impedance Z of the material can also be adjusted by improving the internal structure of the filter 400 . The structure of the filter according to the exemplary embodiment of the present disclosure will be described below with reference to FIGS. 5 to 13 .

5 and 6 respectively show a schematic cross-sectional view and a perspective view of a filter according to another exemplary embodiment of the present disclosure. In the embodiment shown in FIG. 5 , the first coupling layer 530 may be provided with at least one through hole 532 , and the through hole 532 may penetrate the first coupling layer 530 along the illustrated Z direction. In this way, setting the through hole 532 can effectively change the compactness of the internal structure of the first coupling layer 530 by reducing the projected area of the first coupling layer 530 in the X direction. This can change the speed at which sound waves propagate in the material of the first coupling layer 530 and the density of the material of the first coupling layer 530 . Therefore, the acoustic impedance Z can be adjusted reasonably, and the coupling strength between the symmetric mode and the antisymmetric mode can be weakened.

In some embodiments, as shown in FIG. 5 , at least one through hole 532 includes a plurality of through holes 532 extending between the first resonator 510 and the second resonator 520 in parallel along the Z axis. In this way, the coupling strength between the first resonator 510 and the second resonator 520 can be further reduced. It should be understood that the parallel here does not require absolute parallelism in a strict sense, but allows a certain degree of non-parallelism among the plurality of through holes 532 . Furthermore, in the embodiment of FIG. 5 , the through holes 532 are substantially perpendicular to the second electrode 512 and the third electrode 521 . It should be understood that this is only illustrative, and the through hole 532 and the second electrode 512 and the third electrode 521 may form other angles, such as 85 degrees, 80 degrees, 75 degrees, and so on. Specific angles are not limited by the embodiments of the present disclosure.

In other embodiments, the first coupling layer 530 may also be provided with a blind hole (not shown). Compared with the through hole 532 shown in FIG. 5 , the blind hole does not completely penetrate the first coupling layer 530 . The blind hole can also change the tightness of the internal structure of the first coupling layer 530 , so that the coupling degree between the symmetric mode and the anti-symmetric mode can be weakened by adjusting the acoustic impedance Z reasonably. It should be understood that the depth of the blind hole entering the first coupling layer 530 can be set according to different requirements, which is not limited in the present invention.

One possible form of via 632 is shown in the embodiment shown in FIG. 6 . As shown, the via hole 632 may have a rectangular cross-section on the XY plane. However, it should be understood that this is only illustrative, not restrictive, and in other embodiments, the through hole 632 may have other shapes, such as circle, triangle, pentagon and so on. Moreover, as shown in FIG. 6 , the through holes 632 may be arranged in an array along the directions of the X-axis and the Y-axis. The number of vias 632 in the array can be adjusted according to specific design requirements.

Fig. 7 shows a schematic cross-sectional view of a filter 700 according to another exemplary embodiment of the present disclosure. In the illustrated embodiment, the filter 700 may further include a third resonator 740 arranged under the second resonator 720 in a stacked manner. A second coupling layer 750 may also be provided between the third resonator 740 and the second resonator 720 for coupling the third resonator 740 and the second resonator 720 together.

In some embodiments, the second coupling layer 750 can be similar to the first coupling layer 730 described above, including that the acoustic impedance Z can be between 4*10 ⁶ kg/m ² s and 16*10 ⁶ kg/m ² s material between. Similarly, this material may also be one or more of SiO ₂ , SiOC, SiOF and W. In this way, reasonable control of the coupling strength between the symmetric mode and the anti-symmetric mode can be achieved.

In some embodiments, as shown in FIG. 7 , each third resonator 740 may include a fifth electrode 741, a sixth electrode 742, and a third piezoelectric layer disposed between the fifth electrode 741 and the sixth electrode 742. 743. Although three

resonators

710, 720, 740 in a stacked arrangement are shown, it should be understood that a greater number of resonators in a stacked arrangement may be provided, for example four, five or more. The specific number is not limited by the embodiments of the present disclosure. Therefore, by using other resonators between the resonators, the coupling strength is regulated to meet the design requirements.

In some embodiments, the third piezoelectric layer 743 may be similar to the first piezoelectric layer 713 or the second piezoelectric layer 723 described above, including a material with a coupling coefficient not lower than 20%. This material can be lithium niobate or lithium tantalate.

Fig. 8 shows a schematic perspective view of a filter 800 according to another exemplary embodiment of the present disclosure. In the illustrated embodiment, the first resonator 810 may include at least one first recess 815 extending from a portion of the first piezoelectric layer 813 not covered by the first electrode along the Z direction. through the first piezoelectric layer 813 . In other embodiments, the first recess 815 may extend through the first piezoelectric layer 813 along the Z direction, and reach the second electrode 812, the first coupling layer 830, and the third electrode 821 below the first piezoelectric layer 813. , any one of the second piezoelectric layer 823 and the fourth electrode 822 . By setting the first recess 815 extending along the Z direction and penetrating through the first piezoelectric layer 813, and by suppressing the stray modes of the first resonator 810 and the second resonator 820 and confinement of energy, it is possible to Good for achieving a clean and smooth filter response.

In some embodiments, at least one second recess (not shown) similar to the first recess 815 may also be provided on the other side of the filter 800 . The second concave portion is disposed on the second resonator 820 and extends from a portion of the second piezoelectric layer 823 not covered by the fourth electrode 822 through the second piezoelectric layer 823 . In this way, by symmetrically arranging the first concave portion 815 and the second concave portion, more excellent energy confinement and spurious mode suppression can be achieved, so that the filter 800 can meet the requirements of better out-of-band suppression and higher quality factor. need.

It can be understood that, similar to the first concave portion 815, in some embodiments, the second concave portion can also extend to pass through the second piezoelectric layer 823, the third electrode 821, the first coupling layer 830, the second electrode 812, the The first piezoelectric layer 813 and the first electrode 811 .

FIG. 9 shows a simulated admittance curve of the filter 800 in FIG. 8 . It can be seen from FIG. 9 that there is no obvious spurious phenomenon in the admittance curve, which shows that the structure of the first concave portion 815 on the filter 800 has realized the suppression of the spurious modes, and the filter 800 is good. Performance is guaranteed.

Fig. 10 shows a schematic perspective view of a filter 1000 according to another exemplary embodiment of the present disclosure. In the illustrated embodiment, the filter 1000 may further include at least one metal piece 1016 configured to be coupled to the first electrode 1011 . In the embodiment of FIG. 10 , the metal piece 1016 can be in a strip structure, and is disposed on the first electrode 1011 close to the edge and generally extends along the X direction. The metal piece 1016 can be used to suppress the spurious effect of the filter 1000 and increase the flatness of the mode curve, so as to further optimize the performance of the filter 1000 .

FIG. 11 shows a simulated admittance curve of the filter 1000 in FIG. 10 . It can be seen from FIG. 11 that there is no obvious stray phenomenon in the admittance curve, which indicates that the structure of the concave portion 1015 and the metal piece 1016 on the filter 1000 can effectively eliminate the adverse effect caused by the stray effect.

Fig. 12 shows a schematic perspective view of a filter 1200 according to another exemplary embodiment of the present disclosure. As shown, in some embodiments, the metal piece 1216 may be further disposed on the first electrode 1211 near the edge and generally extend along the X direction and the Y direction, so as to substantially surround the edge of the first electrode 1211 . In other embodiments, the metal piece 1216 can also be presented in other ways, for example, the metal piece 1216 can form one of polygonal, circular, elliptical, well-shaped, honeycomb shapes or any combination thereof above the first electrode 1211 .

In some embodiments, the

metal parts

1016, 1216 may include various metal materials, such as Al, Cu, Au, Ag, Pt, W and other materials. Of course, it should be understood that the materials listed here for the

metal parts

1016, 1216 are merely exemplary and not limiting. The

metal pieces

1016, 1216 may be made of other materials. The specific material is not limited by the embodiments of the present disclosure.

Fig. 13 shows a schematic perspective view of a filter according to another exemplary embodiment of the present disclosure. In the embodiment shown in FIG. 13 , the filter 1300 further includes a substrate 1360 at its bottom, used to support other structures of the filter 1300, for example, to provide structures for the first resonator 1310 and the second resonator 1320 support. The substrate 1360 includes a Bragg reflective layer. As shown in FIG. 13 , the Bragg reflection layer is composed of multilayer thin films 1370 stacked together. In a further embodiment, these multi-layer films 1370 are stacked with a film with a higher acoustic impedance Z and a film with a lower acoustic impedance Z spaced apart. Therefore, when the sound wave passes through the interface between the thin film with high acoustic impedance Z and the thin film with high acoustic impedance Z, the reflection of the acoustic signal will occur. The greater the difference between the acoustic impedance Z of the two materials, the easier it is to form a strong reflection, thereby reducing the spurious signal at the boundary and improving the performance of the filter 1300 .

It should be understood that the drawings of the present disclosure are only some exemplary embodiments. The structures in each figure can be combined with each other to further optimize the filtering performance of the filter. For example, in the filter 700 having multiple stacked

resonators

710, 720, 730 shown in FIG. 7, at least A through hole 532 . Alternatively, in the

first coupling layer

830, 1030, 1230, 1330 of the

filter

800, 1000, 1200, 1300 shown in FIG. 8, FIG. 10, FIG. 12 or FIG. 13, the through hole 532 in FIG. . As another example, above the first electrode 511 or below the fourth electrode 522 of the filter 500 shown in FIG. 5 , the

metal pieces

1016 and 1216 shown in FIG. 10 and FIG. 12 can be arranged to suppress stray.

Such metal pieces

1016, 1216 can also be arranged above the first electrode 711 or below the sixth electrode 742 or in the middle electrode of the filter 700 in FIG. It should be understood that other combinations can also be conceived based on these drawings, and the specific ways fall within the scope of the present disclosure, and will not be repeated here.

FIG. 14 to FIG. 16 respectively show schematic views of different angles of a multi-port filter set composed of a plurality of unit filters according to embodiments of the present disclosure. As shown in FIG. 14 , a two-port set 1400 composed of two unit filters 1450 connected in series is shown in the figure. It can be understood that the unit filter 1450 here may be any filter described above. In some embodiments, each unit filter 1450 may be identical. In some other embodiments, the unit filters 1450 may also be different from each other. That is to say, one or more filters among the

filters

800, 1000, 1200, and 1300 shown in FIG. 8, FIG. 10, FIG. 12 or FIG. 13 can be replaced with the filter 1450 in FIG. 14 . In a further embodiment, the through holes, metal parts or recesses in the filters in the above figures can be properly arranged and combined, so that the perfect suppression of spurs can be achieved while ensuring a flat electrical response, thereby providing The quality factor of the filter.

Filters according to embodiments of the present disclosure may be integrated into a modular chip. Filters can be used in various environments, such as mobile phones, base stations, radars, etc., for wireless communication.

In another aspect of the present disclosure, a radio frequency system is provided. The radio frequency system includes a radio frequency circuit and the filter described above. In the embodiment of the present disclosure, the radio frequency system may include an independent antenna, an independent radio frequency front end (RF front end, RFFE) device, and an independent radio frequency chip. RF chips are sometimes called receivers, transmitters or transceivers. Antennas, RF front-end devices, and RF processing chips can all be manufactured and sold separately. Of course, the radio frequency system can also use different devices or different integration methods based on power consumption and performance requirements. For example, if some devices belonging to the radio frequency front end are integrated into the radio frequency chip, even the antenna and the radio frequency front end devices are integrated into the radio frequency chip, the radio frequency chip may also be called a radio frequency antenna module or an antenna module.

In yet another aspect of the present disclosure, an electronic device is provided. The electronic device generally includes a processor, a circuit board, and includes the filter described above, wherein the filter and the processor are arranged on the circuit board. Radio frequency systems and electronic devices can be adapted for wireless communication in a variety of practical environments. Figure 17 shows a schematic diagram of an example wireless communication system 1700 in which embodiments of the disclosure may be implemented. As shown in FIG. 17 , a wireless communication system 1700 includes a terminal 1701 and a base station 1702 . Exemplarily, the electronic device may include, but is not limited to, one of the terminals or base stations shown in FIG. 17 .

It should be understood that in a wireless communication system, devices may be divided into devices that provide wireless network services and devices that use wireless network services. Devices that provide wireless network services refer to devices that form a wireless communication network, which can be referred to as network equipment or network elements for short. Network equipment is usually owned by operators (such as China Mobile and Vodafone) or infrastructure providers (such as tower companies), and these manufacturers are responsible for operation or maintenance. Network equipment can be further divided into radio access network (radio access network, RAN) equipment and core network (core network, CN) equipment. Typical RAN equipment includes a base station (base station, BS).

It should be understood that sometimes the base station may also be called a wireless access point (access point, AP), or a transmission reception point (transmission reception point, TRP). Specifically, the base station can be a general node B (generation Node B, gNB) in a 5G new radio (new radio, NR) system, or an evolved node B (evolutional Node B, eNB) in a 4G long term evolution (long term evolution, LTE) system. ). According to the physical form or transmission power of the base station, the base station can be divided into a macro base station or a micro base station. Micro base stations are also sometimes referred to as small base stations or small cells.

Devices using wireless network services are usually located at the edge of the network, and may be referred to as terminals for short. The terminal can establish a connection with the network equipment, and provide users with specific wireless communication services based on the services of the network equipment. It should be understood that, because the relationship between the terminal and the user is closer, it is sometimes called user equipment (user equipment, UE), or a subscriber unit (subscriber unit, SU). In addition, compared with the base station usually placed in a fixed location, the terminal often moves with the user, and is sometimes called a mobile station (mobile station, MS). In addition, some network devices, such as a relay node (relay node, RN) or a wireless router, etc., can sometimes be considered as terminals because they have a UE identity or belong to a user.

Specifically, the terminal can be a mobile phone (mobile phone), a tablet computer (tablet computer), a laptop computer (laptop computer), a wearable device (such as a smart watch, a smart bracelet, a smart helmet, smart glasses), and other Devices with wireless access capabilities, such as smart cars, various Internet of things (IOT) devices, including various smart home devices (such as smart meters and smart home appliances) and smart city devices (such as security or monitoring equipment, Intelligent road traffic facilities), etc.

According to different transmission directions, the transmission link from the terminal 1701 to the base station 1702 is marked as uplink (uplink, UL), and the transmission link from the base station to the terminal is marked as downlink (downlink, DL). Similarly, data transmission in the uplink may be abbreviated as uplink data transmission or uplink transmission, and data transmission in the downlink may be abbreviated as downlink data transmission or downlink transmission.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are merely example forms of implementing the claims.

Claims

A filter comprising:

The first resonator, including:

first electrode;

the second electrode; and

a first piezoelectric layer disposed between the first electrode and the second electrode;

A second resonator comprising:

third electrode;

a fourth electrode; and

a second piezoelectric layer disposed between the third electrode and the fourth electrode; and

a first coupling layer located between the first resonator and the second resonator,

Wherein the electromechanical coupling coefficient of at least one of the first resonator and the second resonator is not lower than 20%.
A filter comprising:

first resonator;

a second resonator; and

The first coupling layer is located between the first resonator and the second resonator, the first coupling layer is provided with a hole structure, and the hole structure is used to weaken the first resonator and the second resonator. The coupling strength between the second resonators.
The filter according to claim 2, wherein the hole structure comprises at least one through hole or blind hole, and the at least one through hole penetrates through the first coupling layer.
The filter according to claim 3, wherein the first resonator, the first coupling layer and the second resonator are sequentially stacked along the first direction, and the at least one through hole or blind hole includes multiple a plurality of through holes or blind holes, and the plurality of through holes extend in parallel between the first resonator and the second resonator along a second direction perpendicular to the first direction.
A filter according to any one of claims 3 to 4, wherein said first resonator comprises:

first electrode;

second electrode;

a first piezoelectric layer positioned between the first electrode and the second electrode; and

At least one first recess extending through the first piezoelectric layer from a portion of the first piezoelectric layer not covered by the first electrode.
The filter according to claim 5, wherein said second resonator comprises:

third electrode;

the fourth electrode;

a second piezoelectric layer located between the third electrode and the fourth electrode; and

At least one second recess extending from a portion of the second piezoelectric layer not covered by the fourth electrode through the second piezoelectric layer.
The filter according to claim 6, wherein said at least one first recess extends to sequentially penetrate through said first piezoelectric layer, said second electrode, said first coupling layer, said third electrode, said the second piezoelectric layer and the fourth electrode.
The filter according to claim 7, wherein the at least one second recess extends to sequentially penetrate through the second piezoelectric layer, the third electrode, the first coupling layer, the second electrode, the The first piezoelectric layer and the first electrode.
A filter according to any one of claims 6 to 8, further comprising:

At least one metal piece is configured to be coupled to the first electrode or the fourth electrode.
The filter according to any one of claims 6 to 9, wherein at least one of the first resonator and the second resonator includes a material having an electromechanical coupling coefficient of not less than 20%.
The filter according to any one of claims 2 to 10, wherein the first coupling layer comprises a material with an acoustic impedance between 4*10 6 kg/m 2 s and 16*10 6 kg/m 2 s.
The filter according to any one of claims 2 to 11, wherein at least one of the first piezoelectric layer and the second piezoelectric layer comprises lithium niobate or lithium tantalate.
The filter according to claim 12, wherein said lithium niobate is one or more of X-cut lithium niobate, Y-cut lithium niobate, and -18°Y Y lithium niobate, and said lithium tantalate is One or more of X-cut lithium tantalate, Y-cut lithium tantalate, and -18°Y lithium tantalate.
The filter according to any one of claims 2 to 13, wherein the first coupling layer comprises one or more of SiO 2 , SiOC, SiOF and W.
A filter according to any one of claims 2 to 14, further comprising:

a substrate disposed on a side of the second resonator opposite to the first resonator for supporting the first resonator and the second resonator, wherein the substrate includes a Bragg reflection layer , the Bragg reflection layer is composed of stacked multi-layer films.
A radio frequency system comprising:

Filter and radio frequency circuit according to any one of claims 1-15.
An electronic device comprising:

processor;

circuit boards; and

A filter according to any one of claims 1-15,

Wherein the filter and the processor are arranged on the circuit board.