CN115996038B - Filter, multiplexer and communication equipment - Google Patents

Abstract

In an embodiment of the disclosure, a filter, a multiplexer, and a communication device are provided, where the filter includes an input terminal, an output terminal, one or more series resonators, and one or more parallel resonators, where an L value of an N-stage resonator near the input terminal is smaller than an L value of the remaining resonators, where the L value indicates a distance between a boundary of any one side of an overlapping region of a first electrode, a piezoelectric thin film layer, and a second electrode of the resonator and a cavity boundary of the resonator, and N is a positive integer. By the processing scheme, the power capacity of the filter is improved on the premise of considering the insertion loss of the filter.

Description

Filter, multiplexer and communication equipment

Technical Field

The invention relates to the technical field of semiconductor devices, in particular to a filter, a multiplexer and communication equipment.

Background

With the continuous development of mobile communication technology, the frequency spectrum complexity trend is increasingly accelerated, and the number of frequency bands used in mobile communication has been greatly increased from 4 frequency bands in the early 2000 to more than 50 frequency bands today.

The complexity of the frequency spectrum makes the requirements on the performance of the radio frequency system become more and more severe, and the transmission rate, service life and reliability of the radio frequency system can be improved by good radio frequency filter performance, so that the continuous improvement on the filter performance is highly demanded, and the continuous improvement on the filter performance is mainly characterized by lower insertion loss, wider bandwidth, higher out-of-band rejection, higher roll-off and higher power capacity. In particular the power capacity, which determines the maximum power of the passband signal that can be input to the filter, and the height of which directly determines the range and context of application of the filter.

Disclosure of Invention

In view of the above, embodiments of the present disclosure provide a filter, a multiplexer, and a communication device, which at least partially solve the problems in the prior art.

In a first aspect, a filter is provided, comprising: an input, an output, one or more series resonators and one or more parallel resonators, wherein

The L value of the N-stage resonator near the input end is smaller than that of the rest resonators, wherein the L value indicates the distance between the boundary of any side of the overlapping region of the first electrode, the piezoelectric film layer and the second electrode of the resonator and the cavity boundary of the resonator, and N is a positive integer.

According to a specific implementation of an embodiment of the present disclosure, the L values of the one or more series resonators and/or the one or more parallel resonators satisfy: l is less than or equal to 5 μm and less than or equal to 18 μm.

According to a specific implementation of an embodiment of the disclosure, the L value of the N-stage resonator near the input end satisfies: -5 μm.ltoreq.L <3 μm.

According to a specific implementation of an embodiment of the disclosure, the L values of the remaining resonators satisfy: l is more than or equal to 3 μm and less than or equal to 18 μm.

According to one specific implementation of an embodiment of the present disclosure, n=2.

According to one specific implementation of an embodiment of the present disclosure, n=3.

According to a specific implementation of an embodiment of the disclosure, the L values of the N-stage resonators close to the input are different.

According to a specific implementation of an embodiment of the present disclosure, the L value of the N-stage resonator near the input end gradually increases with increasing distance from the input end.

According to a specific implementation of an embodiment of the disclosure, the L values of the remaining resonators are different.

According to a specific implementation of an embodiment of the disclosure, the L value of the remaining resonators increases gradually with increasing distance from the input.

In a second aspect, a multiplexer is provided, including a filter according to the first aspect of the embodiments of the present disclosure and any implementation thereof.

In a third aspect, a communication device is provided, which includes a filter according to the first aspect of the embodiments of the present disclosure and any implementation manner thereof, or a multiplexer according to the second aspect of the embodiments of the present disclosure.

The filter in the embodiment of the disclosure comprises an input end, an output end, one or more series resonators and one or more parallel resonators, wherein the L value of an N-stage resonator close to the input end is smaller than the L value of the rest resonators, the L value indicates the distance between the boundary of any side of the overlapping area of the first electrode, the piezoelectric film layer and the second electrode of the resonator and the cavity boundary of the resonator, and N is a positive integer. By the processing scheme, the power capacity of the filter is improved on the premise of considering the insertion loss of the filter.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.

FIG. 1 is a schematic diagram of a filter;

FIG. 2a is a top view of a resonator provided by an embodiment of the present disclosure;

FIG. 2b is a cross-sectional view of the resonator taken along line A-A of FIG. 2a provided by an embodiment of the present disclosure;

FIG. 2c is a cross-sectional view of the resonator taken along line A-A of FIG. 2a provided by an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of a filter according to an embodiment of the disclosure;

FIG. 4 is a graph comparing failure rates of the filter of the presently disclosed embodiments with the filter of the comparative embodiments;

FIG. 5 is a graph comparing insertion loss of a filter according to an embodiment of the disclosure with that of a filter according to a comparative embodiment;

fig. 6 is a schematic structural diagram of another filter according to an embodiment of the disclosure;

fig. 7 is a schematic structural diagram of a duplexer provided in an embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

Other advantages and effects of the present disclosure will become readily apparent to those skilled in the art from the following disclosure, which describes embodiments of the present disclosure by way of specific examples. It will be apparent that the described embodiments are merely some, but not all embodiments of the present disclosure. The disclosure may be embodied or practiced in other different specific embodiments, and details within the subject specification may be modified or changed from various points of view and applications without departing from the spirit of the disclosure. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by one of ordinary skill in the art without inventive effort, based on the embodiments in this disclosure are intended to be within the scope of this disclosure.

It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.

It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concepts of the disclosure by way of illustration, and only the components related to the disclosure are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.

In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.

In view of the increasing requirements on the power capacity of the filter, the embodiments of the disclosure, starting from the structure of the resonators included in the filter, define the structure of the resonators and define the positions of the resonators in the filter, so as to propose a filter with high power capacity.

First, referring to fig. 1, a typical filter structure is described. The filter shown in fig. 1 includes a first series resonator S1, a second series resonator S2, a third series resonator S3, and a fourth series resonator S4, and further includes a first parallel resonator P1 and a second parallel resonator P2. IN addition, the filter shown IN fig. 1 may further include an input terminal IN and an output terminal OUT.

In other words, the filter may include at least an input, an output, one or more series resonators, and one or more parallel resonators. Typically, the power densities of the first stage resonator and the second stage resonator near the signal input of the filter are the greatest and the most vulnerable. The first series resonator S1 is a first-stage resonator, and the first parallel resonator P1 is a second-stage resonator, and the two-stage resonators have the greatest power density and are most easily damaged.

Further, it should be noted that while the first and second stage resonators are shown in fig. 1 as comprising a single resonator, it is understood that each stage resonator, such as the first and second stage resonators, may comprise multiple resonators in parallel and/or in series, i.e., each stage resonator may comprise multiple resonators.

In order to avoid damage to the filter due to excessive power density, the resonant frequencies of the first stage resonator and the second stage resonator may be limited to a specified range, thereby reducing the power density of these resonators to increase the overall power capacity of the filter. However, this design sacrifices some design freedom (e.g., the resonant frequencies of the first stage resonator and the second stage resonator) and is detrimental to designing a filter with better performance.

According to the embodiment of the disclosure, the relation between the relative positions of the supporting layer and the sandwich structure (the first electrode, the piezoelectric film layer and the second electrode) of the resonator and the performance of the resonator is researched, so that a novel filter structure is provided, and the improvement of the power capacity of the filter is realized on the premise of considering the insertion loss of the filter.

First, with reference to fig. 2 a-2 c, a filter structure of an embodiment of the present disclosure is described, it being understood that the illustrated resonator may be a bulk acoustic wave resonator or other type of resonator. Wherein fig. 2a is a top view of the resonator, fig. 2b and 2c are cross-sectional views of the resonator taken along line A-A of fig. 2a, and specifically show cross-sectional views of the resonator sandwich structure (first electrode, piezoelectric film layer and second electrode) at different relative positions with respect to the support layer, in which:

110: the first electrode can be an upper electrode or a lower electrode, and the material can be a metal material such as molybdenum, gold, aluminum, magnesium, tungsten, copper, chromium and the like or a composite material composed of a plurality of metals.

In addition, the surface of the first electrode can be provided with a mass loading layer, and the material of the mass loading layer can be selected from metal materials such as molybdenum, gold, aluminum, magnesium, tungsten, copper, chromium and the like or composite materials formed by a plurality of metals, or dielectric materials such as silicon oxide, silicon nitride and the like, or piezoelectric materials such as aluminum nitride, zinc oxide and the like.

108: the piezoelectric thin film layer may be selected from piezoelectric materials such as single crystal aluminum nitride, polycrystalline aluminum nitride, zinc oxide, PZT, and the piezoelectric thin film layer may be selected from the above piezoelectric materials doped with rare earth elements (for example, rare earth elements such as scandium, yttrium, magnesium, titanium, lanthanum, cerium, praseodymium, etc.).

106: the second electrode can be an upper electrode or a lower electrode, when 110 indicates the upper electrode, 106 is a lower electrode, and when 110 indicates the lower electrode, 106 is an upper electrode, and the material can be molybdenum, gold, aluminum, magnesium, tungsten, copper, chromium and other metal materials or composite materials formed by multiple metals.

In addition, the surface of the second electrode can be provided with a mass loading layer, and the material of the mass loading layer can be selected from metal materials such as molybdenum, gold, aluminum, magnesium, tungsten, copper, chromium and the like or composite materials formed by a plurality of metals, or dielectric materials such as silicon oxide, silicon nitride and the like, or piezoelectric materials such as aluminum nitride, zinc oxide and the like.

202: the substrate is selected from silicon, germanium, silicon carbide, indium arsenide, gallium arsenide, indium phosphide or other III/V compound semiconductors, and also comprises a multilayer structure formed by the semiconductor materials, or is silicon-on-insulator (SOI), ceramic substrate, quartz or glass substrate and the like.

200: the support layer is made of one or more of silicon dioxide, silicon nitride, aluminum oxide and aluminum nitride, or a substrate material.

A partial region of the support layer 200 is hollowed out to form a cavity 360 as an example of an acoustic mirror. The acoustic mirror may be a cavity or bragg reflective layer or other material having a relatively large acoustic impedance difference from the electrode material, the method and form of forming the acoustic mirror is not limited, and the acoustic mirror may be formed supported by other materials on the substrate 202.

In the thickness direction, one side of each of the first electrode and the second electrode is provided with an acoustic mirror, so that an acoustic wave is confined inside the piezoelectric resonator. In addition, an overlapping region of the first electrode side acoustic mirror, the first electrode, the piezoelectric thin film layer, the second electrode, and the second electrode side acoustic mirror projected in the lamination direction is referred to as an effective region AR of the resonator.

In fig. 2b and 2c, the region denoted by reference numeral 500 is an overlapping region of the first electrode 110, the piezoelectric thin film layer 108, and the second electrode 106, and reference numeral 5001 is a boundary of the overlapping region 500. Reference numeral 2001 denotes a boundary of the cavity 360 on the side of the second electrode 106, i.e., an inner boundary of the support layer 200. The distance between the two boundaries 2001 and 5001 is L.

When the cavity 360 on the side of the second electrode 106 is larger than the region 500, the distance L is larger than 0 (as in the case of fig. 2 b); in addition, when the cavity 360 on the side of the second electrode 106 is smaller than the region 500, L is smaller than 0 (as in the case of fig. 2 c); in addition, when the second electrode 106 side cavity 360 is equal to the region 500, l=0, that is, the second electrode 106 side cavity 360 overlaps the region 500. In the disclosed embodiment, as shown in fig. 2a, the shape of the resonator may be various shapes such as a hexagon, and thus the distance between the boundary of the overlap region 500 and the boundary of the cavity 360 may refer to the distance between the boundary of either side of the overlap region and the boundary of the cavity of the resonator. And the distance L may indicate the smallest of the distances between the respective sides of the overlap region and the cavity boundary of the resonator when the distances between the respective sides and the cavity boundary of the resonator are not the same. In addition, it can be seen that the distance L has directionality, i.e., L is positive when the cavity 360 on the side of the second electrode 106 is larger than the region 500, and L is negative when the cavity 360 on the side of the second electrode 106 is smaller than the region 500.

The larger the distance L, the more thoroughly the resonator vibrates in the longitudinal axis direction, the higher the quality factor of the resonator, but the mechanical strength, heat radiation performance of the resonator become poor, and the resonator area increases; conversely, the smaller the distance L, the lower the quality factor of the resonator, in particular when L is negative, but the higher the mechanical strength of the resonator and the better the heat dissipation performance. Therefore, in the embodiment of the present disclosure, the range of values of the distance L is as follows, taking the above factors into consideration: l1 is less than or equal to-5 μm and less than or equal to 18 μm.

That is, in the embodiments of the present disclosure, in order to achieve a compromise in quality factor, mechanical strength, and heat dissipation performance of the resonators, the L values of all resonators may be made to satisfy-5 μm.ltoreq.L1.ltoreq.18 μm. It is particularly advantageous to limit the L value to a range of-5 μm to 18 μm because if the L value is too large (more than 18 μm), the Q value is high although the resonator vibrates sufficiently at this time, the reliability is poor because the support structure is far from the effective region of the resonator. In contrast, if the L value is too small (less than-5 μm), the cavity area of the resonator is small, and the effective resonance area of the resonator is determined by the cavity size, resulting in a lower Q value of the resonator, and in this case, the same effective resonance area occupies a larger layout area, which is not suitable for miniaturization design of the device. Therefore, in the embodiment of the present disclosure, the range of values of the required distance L is as follows: l1 is less than or equal to-5 μm and less than or equal to 18 μm.

In addition, although a resonator of a specific shape is shown in fig. 2a, the resonator may be any shape of a hexagon, a heptagon, an ellipse, etc., and in the embodiment of the present disclosure, a resonator in which at least one side of the resonator satisfies the range of L <3 μm is defined as a first type resonator, and a resonator in which at least one side of the resonator satisfies the range of L <3 μm is defined as a second type resonator. In the embodiment of the present disclosure, the types of resonators are classified with l=3 μm as a standard, because the larger L is, the more sufficiently the resonator vibrates in the longitudinal axis direction, the higher the quality factor of the resonator is, but the mechanical strength, heat radiation performance of the resonator become poor, and the area of the resonator increases; the smaller L the resonator has a lower quality factor, but the resonator has higher mechanical strength and better heat dissipation. And when l=3 μm, the Q value and the heat dissipation characteristic of the resonator are relatively balanced. In other words, since L of the first resonator satisfies-5 μm.ltoreq.L <3 μm, it has better mechanical strength and heat dissipation performance, and thus can accommodate higher power density, while L of the second resonator satisfies 3 μm.ltoreq.L.ltoreq.18 μm, and thus has higher quality factor.

In the above, the relative positions of the support layer 200 of the resonator and the resonator sandwich structure (the first electrode 110, the piezoelectric film layer 108 and the second electrode 106) are described, and a filter comprising such a resonator is described next.

As shown in fig. 3, the topology of a ladder filter according to an embodiment of the present disclosure is a ladder filter formed by series resonators Res1, res3, res5, and Res7 and parallel resonators Res2, res4, res6, and Res 8.

From the signal input end, the resonators Res1 to Res8 are sequentially a first-stage resonator and a second-stage resonator … …, an eighth-stage resonator, any one-stage resonator is a single resonator or a combination formed by mutually connecting a plurality of resonators in series and/or in parallel, the number of stages of the filter can be other values, and the first-stage resonator can also be a parallel resonator.

In order to achieve a passband with a certain bandwidth, the resonant frequency of the parallel resonator in the ladder filter needs to be lower than the resonant frequency of the series resonator and there is a certain frequency difference, which can be achieved by providing a mass loading layer on the parallel resonator.

IN addition, IN is a filter signal input terminal, OUT is a filter signal output terminal, L1 and L2 are a filter signal input terminal IN series inductance and a filter signal output terminal OUT series inductance, respectively, L3, L4, L5 and L6 are filter parallel branch series grounding inductances, that is, parallel resonators Res2, res4, res6 and Res8 are grounded through series grounding inductances L3, L4, L5 and L6, respectively.

IN order to achieve a better matching, LC matching circuits may be included at the signal input IN and/or the signal output OUT. The filter structure shown in fig. 3 is only an example, and the invention is not limited to the ladder-type structure filter stage number, the matching mode and the parallel branch grounding mode.

IN general, IN the filter shown IN fig. 3, the power densities of the first-stage resonator (series resonator Res 1) and the second-stage resonator (parallel resonator Res 2) near the filter signal input terminal IN are the largest and the most vulnerable. IN the embodiment of the disclosure, IN order to improve the overall power capacity of the filter, a first resonator with higher mechanical strength and better heat dissipation performance can be adopted IN the two-stage resonators of the first-stage resonator and the second-stage resonator of the signal input end IN, and IN order to consider the insertion loss characteristic of the filter, a second resonator with higher quality factor can be adopted IN the remaining resonators insensitive to the power capacity of the filter, so that the filter with better comprehensive performance can be obtained.

Specifically, as shown IN fig. 3, IN the embodiment of the present disclosure, the first-stage resonator and the second-stage resonator near the signal input terminal IN adopt a first resonator structure (for example, l1= -1.5 μm), and the remaining resonators adopt a second resonator structure (for example, l1=5 μm). In contrast, in the first comparative example, all resonators in the filter were of the second resonator structure (e.g., l1=5 μm), and in the second comparative example, all resonators in the filter were of the first resonator structure (e.g., l1= -1.5 μm).

As shown IN fig. 4, the relations between the filter failure rates and the input power of the embodiments of the present disclosure, the first comparative embodiment and the second comparative embodiment are shown, wherein the sample size of the filter is 200 samples, the vertical axis is the failure rate of the filter, the horizontal axis is the power of the high-frequency signal input by the signal input terminal IN of the filter, the curve marked by a circle is the curve of the embodiment of the present disclosure, the curve marked by a rectangle is the curve of the first comparative embodiment, and the curve marked by a triangle is the curve of the second comparative embodiment.

As shown, as the input power increases (horizontal axis), the proportion of filter failure increases. The filters of the embodiments of the present disclosure (the circles marked curves) begin to appear a failed filter in the sample at an input power of 28dBm, and all filters fail at an input power of 37.5 dBm; the filter of the first comparative example (rectangular marked curve) started to appear as a dead filter in the sample at an input power of 26dBm, and all filters failed at an input power of 32 dBm; the filter of the second comparative example (triangle marked curve) started to appear as a dead filter in the sample at an input power of 28.5dBm, and all filters failed at an input power of 38 dBm. As can be seen from the figure, the power capacity of the filter of the embodiment of the present disclosure is about 2.5dB higher than that of the filter of the first comparative embodiment, and the power capacity of the filter of the embodiment of the present disclosure is comparable to that of the filter of the second comparative embodiment.

Fig. 5 shows the insertion loss frequency characteristic curves of the filters of the embodiments of the present disclosure, the first comparative example and the second comparative example, wherein the horizontal axis is frequency, the vertical axis is insertion loss, the thin solid line is the insertion loss frequency characteristic curve of the filter of the embodiments of the present disclosure, the thick solid line is the insertion loss frequency characteristic curve of the filter of the first comparative example, and the dotted line is the insertion loss frequency characteristic curve of the filter of the second comparative example. As can be seen, the insertion loss of the embodiment of the present disclosure is comparable to that of the first comparative example, but the power capacity of the embodiment of the present disclosure is 2.5dB better than that of the first comparative example; the disclosed embodiments are comparable to the power capacity of the second comparative embodiment, but the insertion loss of the disclosed embodiments is 0.3dB less than the insertion loss of the second comparative embodiment. Therefore, the filter of the embodiment of the present disclosure has better overall performance than the first and second comparative examples.

A ladder filter topology according to another embodiment of the present disclosure is shown in fig. 6. Unlike the filter shown in fig. 3, the first three stages of the filter employ a first resonator structure and the remaining resonators employ a second resonator structure.

Specifically, the filter shown in fig. 6 includes a ladder-type structure filter composed of series resonators Res1, res3, res5, and Res7 and parallel resonators Res2, res4, res6, and Res 8. From the signal input end, the resonators Res1 to Res8 are sequentially a first-stage resonator and a second-stage resonator … …, an eighth-stage resonator, any one-stage resonator is a single resonator or a combination formed by mutually connecting a plurality of resonators in series and/or in parallel, the number of stages of the filter can be other values, and the first-stage resonator can also be a parallel resonator.

IN the embodiment of the present disclosure, the first-stage resonator (resonator Res 1), the second-stage resonator (resonator Res 2), and the third-stage resonator (resonator Res 3) near the signal input terminal IN adopt a first resonator structure, and the remaining resonators adopt a second resonator structure. The power capacity of the filter shown in fig. 6 will be better than the filter shown in fig. 3, but the insertion loss frequency characteristic will be slightly worse.

Above, two types of filters IN the embodiments of the present disclosure are described with reference to fig. 3 and 6, where the filters include an input terminal IN, an output terminal OUT, one or more series resonators (Res 1, res3, res5, and Res 7), and one or more parallel resonators (Res 2, res4, res6, and Res 8). In the embodiment of the disclosure, in order to achieve the improvement of the power capacity of the filter on the premise of considering the insertion loss of the filter, the L value of the two-stage resonator (example shown in fig. 3) or the three-stage resonator (example shown in fig. 6) close to the input end may be made smaller than the L values of the remaining resonators. Specifically, the L value of the two-stage resonator or the three-stage resonator near the input end may be made to satisfy-5 μm.ltoreq.L <3 μm, and the L values of the remaining resonators satisfy 3 μm.ltoreq.L.ltoreq.18 μm.

In addition, although in the above description, the L value of the two-stage resonator or the three-stage resonator near the input end is made smaller than that of the remaining resonators, it should be understood that the L value of the resonator of the other stages near the input end may be made smaller than that of the remaining resonators, that is, the L value of the N-stage resonator near the input end is smaller than that of the remaining resonators, and N is a positive integer.

In addition, for the former N-stage resonators near the input end, the L values of these resonators may be the same or different, specifically, the L values of the former N-stage resonators near the input end may be such that-5 μm+.l <3 μm are satisfied, and the L values of the respective resonators are equal (for example, -1.5 μm). Alternatively, in order to further balance the insertion loss and the power capacity of the filter, the L value of the N-stage resonator near the input end may be made to gradually increase with increasing distance from the input end, specifically, the L value of the second-stage resonator near the input end may be made to be larger than the L value of the first-stage resonator, and the L value of the third-stage resonator near the input end may be made to be larger than the L value of the second-stage resonator, because the closer to the input end, the greater the power density thereof, so that the balance of the insertion loss and the power capacity of the filter can be better achieved.

Similarly, for other resonators in the filter, on the premise that the L is smaller than or equal to 3 μm and smaller than or equal to 18 μm, the L values of the other resonators can be made different, and the L values of the other resonators gradually increase with the distance from the input end, so that the overall performance of the filter can be further improved.

In the above, the filter structure of the embodiment of the present disclosure is described, and fig. 7 is a schematic diagram of the duplexer structure. The first filter is connected between the antenna port Ant and the first port T1, and the second filter is connected between the antenna port Ant and the second port T2. The pass bands of the first filter and the second filter are not overlapped, the first filter can restrain signals with other frequencies through signals with corresponding pass band frequencies, and the second filter can restrain signals with other frequencies through signals with corresponding pass band frequencies.

The duplexer of the present invention is only used as an example, and is not limited thereto, and the structure of the present invention can be applied to multiplexers such as triplexer, quad-multiplexer, etc., or electronic devices including the above-mentioned filters or multiplexers.

In addition, the embodiment of the disclosure further provides a communication device, where the communication device includes an acoustic wave filter, a duplexer, or a multiplexer as described above with reference to the drawings, and the specific contents thereof are not described herein again.

Accordingly, embodiments of the present disclosure provide the following:

1. a filter, comprising: an input, an output, one or more series resonators and one or more parallel resonators, wherein

The L value of the N-level resonator near the input end is smaller than that of the rest resonators, wherein

The L value indicates a distance between a boundary of any one side of an overlapping region of the first electrode, the piezoelectric thin film layer, and the second electrode of the resonator and a boundary of the cavity of the resonator, and N is a positive integer.

2. The filter of claim 1, the L values of the one or more series resonators and/or the one or more parallel resonators satisfying: l is less than or equal to 5 μm and less than or equal to 18 μm.

3. The filter of 1, the L value of the N-stage resonator near the input end satisfies: -5 μm.ltoreq.L <3 μm.

4. The filter of claim 3, the L values of the remaining resonators satisfying: l is more than or equal to 3 μm and less than or equal to 18 μm.

5. The filter of any one of claims 1-4, n=2.

6. The filter of any one of claims 1-4, n=3.

7. The filter of any of claims 1-4, wherein the L values of the N-stage resonators near the input are different.

8. The filter of any of claims 1-4, wherein the value of L of the N-stage resonator near the input increases progressively with increasing distance from the input.

9. The filter of any of claims 1-4, the L values of the remaining resonators being different.

10. The filter of any of claims 1-4, the L value of the remaining resonators gradually increasing with increasing distance from the input.

11. A multiplexer comprising a filter according to any one of claims 1-10.

12. A communication device comprising a filter according to any one of claims 1-10 or a multiplexer according to claim 11.

The foregoing is merely specific embodiments of the disclosure, but the protection scope of the disclosure is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the disclosure are intended to be covered by the protection scope of the disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims (12)

1. A filter, comprising: an input, an output, one or more series resonators and one or more parallel resonators, wherein

The L value of the N-stage resonator near the input end is smaller than that of the rest resonators, wherein the L value indicates the distance between the boundary of any side of the overlapping region of the first electrode, the piezoelectric film layer and the second electrode of the resonator and the cavity boundary of the resonator, and N is a positive integer.

2. The filter according to claim 1, characterized in that the L value of the one or more series resonators and/or the one or more parallel resonators satisfies: l is less than or equal to 5 μm and less than or equal to 18 μm.

3. The filter of claim 1, wherein the L value of the N-stage resonator near the input satisfies: -5 μm.ltoreq.L <3 μm.

4. A filter according to claim 3, wherein the L values of the remaining resonators satisfy: l is more than or equal to 3 μm and less than or equal to 18 μm.

5. The filter of any of claims 1-4, wherein N = 2.

6. The filter of any of claims 1-4, wherein N = 3.

7. The filter of any of claims 1-4, wherein the L values of the N-stage resonators near the input are different.

8. The filter of any of claims 1-4, wherein the value of L of the N-stage resonator near the input increases progressively with increasing distance from the input.

9. The filter of any of claims 1-4, wherein the L values of the remaining resonators are different.

10. The filter of any of claims 1-4, wherein the L value of the remaining resonators increases gradually with increasing distance from the input.

11. A multiplexer comprising a filter according to any one of claims 1-10.

12. A communication device comprising a filter according to any one of claims 1-10 or a multiplexer according to claim 11.