Filter

Abstract

The utility model discloses a filter. The filter comprises at least two first resonators which are connected in series; the second resonator is connected with the first resonator in parallel or in series; the second resonator comprises a first sub-resonator group and a second sub-resonator group which are arranged in parallel; each first sub-resonator group at least comprises two first sub-resonators, and the at least two first sub-resonators in the same first sub-resonator group are connected in series; the second sub-resonator group at least comprises a second sub-resonator; the sum S1 of the effective working area of at least two first sub-resonators in the first sub-resonator group and the sum S2 of the effective working area of at least one second sub-resonator in the second sub-resonator group satisfy # imgabs0 #. According to the technical scheme of the utility model, the influence of nonlinear components is weakened or eliminated; the arrangement difficulty of the second resonator is reduced, and the suppression effect of nonlinear components is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of filters, in particular to a filter. Background Art

[0002] Currently, with the rapid development of wireless communication, there are more and more devices for receiving and transmitting information in higher frequency bands. The requirements for radio frequency front-end circuits are becoming more and more stringent, and the market demand for high-performance filters is increasing. Due to its high quality factor, good out-of-band rejection, high rectangularity coefficient and other characteristics, the bulk acoustic wave filter is gradually becoming the mainstream of the market.

[0003] The bulk acoustic wave filter is composed of multiple resonators cascaded according to a specific circuit. When a radio frequency signal is input, the resonators in the filter will generate non-linear components, which will deteriorate the performance of the communication system and affect the reliability of the communication system. Summary of the Utility Model

[0004] The utility model provides a filter to solve the problem that the non-linear components in the prior art affect the normal operation of the filter.

[0005] A filter provided by the utility model includes at least two first resonators connected in series;

[0006] It further includes a second resonator, which is connected in parallel or in series with the first resonator;

[0007] The second resonator includes a first sub-resonator group and a second sub-resonator group connected in parallel;

[0008] The first sub-resonator group includes at least two first sub-resonators, and at least two first sub-resonators in the same first sub-resonator group are connected in series; the second sub-resonator group includes at least one second sub-resonator;

[0009] The sum S1 of the effective working area areas of at least two first sub-resonators in the first sub-resonator group and the sum S2 of the effective working area areas of at least one second sub-resonator in the second sub-resonator group satisfy

[0010] Optionally, at least two first sub-resonators in the same first sub-resonator group share a bottom electrode layer and the top electrode layers are not connected to each other.

[0011] Optionally, at least two first sub-resonators in the same first sub-resonator group are connected in series through a second sub-resonator.

[0012] Optionally, the first resonator group includes two first sub-resonators; the second sub-resonator group includes one second sub-resonator;

[0013] The second sub-resonator is connected in parallel with one of the first sub-resonators; the first sub-resonators are connected in series; the effective working area of each first sub-resonator is the same.

[0014] Optionally, the first sub-resonator group includes two first sub-resonators; the second sub-resonator group includes one second sub-resonator;

[0015] The second sub-resonator is respectively connected in parallel with each first sub-resonator; the effective working area of each first sub-resonator is the same.

[0016] Optionally, both the first sub-resonator and the second sub-resonator include a connection structure; the connection structure penetrates through the piezoelectric layer to connect the top electrode layer of the first sub-resonator and the bottom electrode layer of the second sub-resonator or to connect the bottom electrode layer of the first sub-resonator and the top electrode layer of the second sub-resonator.

[0017] Optionally, the connection structure of the first sub-resonator includes at least two; and / or, the connection structure of the second sub-resonator includes at least two.

[0018] Optionally, one end of the second resonator is electrically connected to an adjacent first resonator, and the other end is grounded.

[0019] Optionally, the second resonator is serially arranged between the signal input end of the filter and the first resonator.

[0020] Optionally, the filter further includes a third resonator;

[0021] The third resonator is arranged in parallel between adjacent first resonators.

[0022] In the technical solution of the present utility model, by arranging a first sub-resonator group and a second sub-resonator group connected in parallel in the filter, and the first sub-resonator group includes at least two first sub-resonators connected in series, and the second sub-resonator group includes at least one second sub-resonator, and the effective working areas of the first sub-resonator group and the second sub-resonator group are approximately the same, while ensuring the normal working performance of the filter, the influence of non-linear components is weakened or eliminated. Compared with two sub-resonators connected in parallel, the second resonator in the embodiment of the present utility model has a larger adjustable space, can reduce the setting difficulty of the second resonator, and improve the suppression effect of non-linear components; multiple sub-resonators can also reduce the power of non-linear signals and further weaken the influence of non-linear components on the filter.

[0023] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present utility model, nor is it used to limit the scope of the present utility model. Other features of the present utility model will become easily understood through the following description. Description of the Drawings

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 is a schematic diagram of the circuit connection of the first filter provided according to an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of the circuit connection of the second filter provided according to an embodiment of the present invention;

[0027] Figure 3 is a connection structure diagram of the first second resonator provided according to an embodiment of the present invention;

[0028] Figure 4 is a connection structure diagram of the second second resonator provided according to an embodiment of the present invention;

[0029] Figure 5 is a comparison diagram of the impedance of the second resonator between the prior art and the present invention;

[0030] Figure 6 is a comparison diagram of the suppression effects between the prior art and the present invention;

[0031] Figure 7 is a schematic diagram of the circuit connection of the third filter provided according to an embodiment of the present invention. Detailed implementation manners

[0032] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here.

[0034] Figure 1It is a schematic diagram of the circuit connection of the first filter provided according to an embodiment of the present invention. Figure 2 It is a schematic diagram of the circuit connection of the second filter provided according to an embodiment of the present invention. Figure 3 It is a connection structure diagram of the first second resonator provided according to an embodiment of the present invention. Figure 4 It is a connection structure diagram of the second second resonator provided according to an embodiment of the present invention. As Figure 1 、 Figure 2 、 Figure 3 and Figure 4 shown, the filter includes:

[0035] At least two serially connected first resonators 1;

[0036] It further includes a second resonator 2, and the second resonator 2 is connected in parallel or in series with the first resonator 1;

[0037] The second resonator 2 includes a first sub-resonator group 21 and a second sub-resonator group 22 which are arranged in parallel;

[0038] The first sub-resonator group 21 includes at least two first sub-resonators 210, and at least two first sub-resonators 210 in the same first sub-resonator group 21 are connected in series; the second sub-resonator group 22 includes at least one second sub-resonator 220;

[0039] The sum S1 of the effective working area areas of at least two first sub-resonators 210 in the first sub-resonator group 21 and the sum S2 of the effective working area areas of at least one second sub-resonator 220 in the second sub-resonator group 22 satisfy

[0040] Wherein, the bulk acoustic wave filter can be formed by connecting multiple resonators of different specifications in series and in parallel. In the technical solution of the embodiment of the present invention, the filter can be provided with at least two serially connected first resonators 1, and the specifications and quantities of each first resonator 1 can be set according to the required performance of the filter to ensure that the filter has the function of allowing or blocking signals in a specific frequency range to pass through. In some embodiments, the filter further includes a third resonator 3; the third resonator 3 is connected in parallel between adjacent first resonators 1. That is, one end of the third resonator 3 is connected to the circuit between two adjacent first resonators 1, and the other end of the third resonator 3 is grounded to change the filtering performance of the filter.

[0041] To solve the problem that the resonator generates non-linear components when inputting radio frequency signals, on the basis of ensuring the performance of the existing filter, a second resonator 2 is set. The second resonator 2 is connected in series or in parallel with the first resonator 1. The series or parallel connection of the second resonator 2 is determined by the performance of the filter itself. The second resonator 2 needs to be set while ensuring that the filtering frequency range of the filter remains unchanged. Therefore, one of the first resonators 1 or the third resonator 3 in the filter can be replaced by the second resonator 2, and the impedance of the second resonator 2 is equal to the impedance of the replaced resonator, thereby ensuring that the working performance of the filter does not change. Figure 5 It is a comparison diagram of the impedance of the second resonator between the prior art and the present invention. The dotted line represents the change of the impedance of the prior art with frequency, and the solid line represents the change of the impedance of the embodiment of the present invention with frequency.

[0042] On this basis, the second resonator 2 includes a first sub-resonator group 21 and a second sub-resonator group 22. The first sub-resonator group 21 includes at least two first sub-resonators 210, and the second sub-resonator group 22 includes at least one second sub-resonator 220. The reason for setting at least three sub-resonators on the basis of the second resonator 2 is that when two sub-resonators are set, the two sub-resonators can only be connected in parallel, and the effective working areas of the two sub-resonators need to be exactly the same to ensure the effect of eliminating non-linear components. In the embodiment of the present invention, at least three sub-resonators are set, that is, at least two first sub-resonators 210 are set in the first sub-resonator group 21, and at least one second sub-resonator 220 is set in the second sub-resonator group 22. The first sub-resonator group 21 and the second sub-resonator group 22 are connected in parallel, and the first sub-resonators 210 are connected in series, and it is required that the sum S1 of the effective working areas of the first sub-resonator group 21 and the sum S2 of the effective working areas of the second sub-resonator group 22 satisfy That is, the effective working areas of the first sub-resonator group 21 and the second sub-resonator group 22 are approximately the same, so as to achieve the effect of eliminating or weakening non-linear components. Among them, the effective working area can be the overlapping area of the top electrode layer 32, the piezoelectric layer and the bottom electrode layer 31 projected on the plane along the thickness direction of the resonator. It can be understood that, compared with the parallel connection between two sub-resonators, when setting at least three sub-resonators, it is not required that the effective working areas of the three sub-resonators are exactly the same. It is only necessary to ensure that the sum of the effective working areas of the first sub-resonators 210 is approximately the same as or the same as the sum of the effective working areas of the second sub-resonator group 22. Similarly, the stacking, shape and position of the sub-resonators can be set to optimize the electromagnetic environment of the second resonator 2. The second resonator 2 in the embodiment of the present invention has a larger adjustable space, which can reduce the setting difficulty of the second resonator 2 and improve the suppression effect of non-linear components.

[0043] Among them, the suppression principle of the non-linear component can be that when the first sub-resonator group 21 and the second sub-resonator group 22 are connected in parallel, that is, at least one first sub-resonator 210 in the first sub-resonator group 21 is connected in parallel with at least one second sub-resonator 220 in the second sub-resonator group 22. The parallel connection method can be that the top electrode layer 32 of one sub-resonator is connected to the bottom electrode layer 31 of the other sub-resonator, and its bottom electrode layer 31 is connected to the top electrode layer 32 of the other sub-resonator. When the sum of the effective working area of the first sub-resonator group 21 and the second sub-resonator group 22 is approximate and in parallel, the input voltages of the first sub-resonator group 21 and the second sub-resonator group 22 are the same and the electrical responses are opposite, thereby weakening or eliminating the influence of the non-linear component on the performance of the overall filter.

[0044] It can be understood that, compared with the parallel connection between two sub-resonators, setting at least three sub-resonators can cause the power of the series-connected sub-resonators to decrease, and then the power of the non-linear component to decrease, thereby weakening the influence of the non-linear component on the overall filtering performance.

[0045] Exemplarily, three sub-resonators are set. The first sub-resonator group 21 includes two first sub-resonators 210, and the second sub-resonator group 22 includes one second sub-resonator 220. The second sub-resonator 220 is connected in parallel with the first sub-resonator 210, that is, top-bottom connection, and the first sub-resonators 210 are connected in series. The sum of the effective working areas of the two first sub-resonators 210 is approximately equal to the effective working area of the second sub-resonator 220. When a radio frequency signal is input into the filter, the first sub-resonator 210 and the second sub-resonator 220 weaken the non-linear signal according to the effective working area, and the parallel connection of the first sub-resonator 210 and the second sub-resonator 220 cancels or weakens the non-linear signal, optimizing the non-linear suppression effect. Figure 6 It is a comparison diagram of the suppression effects of the prior art and the present invention. The dotted line represents the suppression effect of the prior art, and the solid line represents the suppression effect of the embodiment of the present invention. It can be seen that the peak value of the second harmonic of the present invention is 23 dBm, and that of the prior art is 15.7 dBm, achieving the purpose of significantly suppressing the non-linear response.

[0046] In some embodiments, four sub-resonators can be set. Two first sub-resonators 210 and two second sub-resonators 220 can be set; or three first sub-resonators 210 and one second sub-resonator 220 can be set. The embodiments of the present invention do not limit this.

[0047] In the technical solution of the embodiment of the present utility model, by providing a first sub-resonator group and a second sub-resonator group connected in parallel in the filter, and at least two first sub-resonators are connected in series in the first sub-resonator group, and at least one second sub-resonator is included in the second sub-resonator group, and the effective working area of the first sub-resonator group and the second sub-resonator group is approximately the same, while ensuring the normal working performance of the filter, the influence of non-linear components is weakened or eliminated. Compared with two sub-resonators connected in parallel, the adjustment space of the second resonator in the embodiment of the present utility model is larger, the setting difficulty of the second resonator can be reduced, and the suppression effect of non-linear components can be improved; the series connection of multiple sub-resonators can also reduce the power of non-linear signals and further weaken the influence of non-linear components on the filter.

[0048] Optionally, continue to refer to Figure 3 and Figure 4 As shown, at least two first sub-resonators 210 in the same first sub-resonator group 21 share a bottom electrode layer 31 and the top electrode layers 32 are not connected to each other.

[0049] Among them, a top electrode layer 32, a piezoelectric layer, and a bottom electrode layer 31 are included between each sub-resonator. The series connection method between the first sub-resonators 210 can be that two sub-resonators share a bottom electrode layer 31, the top electrode layers 32 are not connected to each other, and the top electrode layers 32 are respectively electrically connected to the same first resonator 1 to realize the series connection of the first sub-resonators 210.

[0050] It can be understood that this setting method will not affect the effective working area of the first sub-resonator 210. The independent setting of the top electrode layers 32 can respectively set the top electrode layers 32 with corresponding areas according to requirements to increase the setting space and error tolerance of the first sub-resonator 210 and ensure the suppression effect of non-linear signals. From the process perspective, since the resonator is prepared layer by layer, by presetting the bottom electrode layer 31 of the same layer, the subsequent work process can be simplified and the preparation efficiency of the filter can be improved.

[0051] Optionally, continue to refer to Figure 3 and Figure 4 As shown, at least two first sub-resonators 210 in the same first sub-resonator group 21 are connected in series through a second sub-resonator 220.

[0052] Among them, the first sub-resonators 210 can also be independently set and connected in parallel with the second sub-resonator 220 respectively. The first sub-resonators 210 connected in parallel with the same second sub-resonator 220 are connected in series. Similarly, the effective working area of the first sub-resonator group 21 can be calculated according to the connection method of the first sub-resonators 210.

[0053] Exemplarily, two first sub-resonators 210 and one second sub-resonator 220 are provided. Each of the first sub-resonators 210 and the second sub-resonator 220 is connected top and bottom, that is, the series connection of the two sub-resonators is realized, and further the function of suppressing the non-linear component is realized.

[0054] Optionally, continue to refer to Figure 3 and Figure 4 As shown, the first resonator group 1 includes two first sub-resonators 210; the second sub-resonator group 22 includes one second sub-resonator 220;

[0055] The second sub-resonator 220 is connected in parallel with one of the first sub-resonators 210; the first sub-resonators 210 are connected in series; the effective working area of each first sub-resonator 210 is the same.

[0056] Among them, in order to ensure the preparation efficiency of the filter and the overall impedance of the filter, the number of sub-resonators in the second resonator 2 cannot be set too many. It is defined that the first resonator group 1 includes two first sub-resonators 210; the second sub-resonator group 22 includes one second sub-resonator 220. The second sub-resonator 220 is interconnected with one of the first sub-resonators 210 top and bottom. The first sub-resonators 210 share a bottom electrode layer 31 and do not share a top electrode layer 32 to realize the series connection of the first sub-resonators 210.

[0057] Among them, setting the effective working area of each first sub-resonator 210 to be the same can make the power shared on the first sub-resonators 210 the same. The effective working area of the second sub-resonator 220 is twice that of the effective working area of the first sub-resonator 210, which not only ensures the non-linear component suppression effect, but also facilitates the calculation and preparation of the effective working areas of the first sub-resonator 210 and the second sub-resonator 220 in the process.

[0058] The technical solution of the embodiment of the present invention, by setting three sub-resonators, the second sub-resonator is connected in parallel with one of the first sub-resonators, the first resonators are connected in series, and the effective working area of each first sub-resonator is the same, avoids the overall impedance of the filter being too large and affecting the working performance, and ensures the non-linear component suppression effect.

[0059] Optionally, continue to refer to Figure 3 and Figure 4 As shown, the first sub-resonator group 21 includes two first sub-resonators 210; the second sub-resonator group 22 includes one second sub-resonator 220;

[0060] The second sub-resonator 220 is respectively connected in parallel with each first sub-resonator 210; the effective working area of each first sub-resonator 210 is the same.

[0061] Among them, in order to ensure the preparation efficiency of the filter and the overall impedance of the filter, the number of sub-resonators in the second resonator 2 cannot be set too many. It is defined that the first resonator 1 group includes two first sub-resonators 210; the second sub-resonator group 22 includes one second sub-resonator 220, and the second sub-resonator 220 is interconnected with each first sub-resonator 210 at the top and bottom, so as to realize the series connection of the two first sub-resonators 210.

[0062] Among them, setting the effective working area of each first sub-resonator 210 to be the same can make the power shared on the first sub-resonator 210 the same. The effective working area of the second sub-resonator 220 is twice that of the first sub-resonator 210, so that the electrical responses of the first sub-resonator 210 and the second sub-resonator 220 are exactly opposite. All the first sub-resonators 210 can cancel or weaken the non-linear components of the second sub-resonator 220, so as to achieve the purpose of suppressing non-linearity and improving the performance of the filter. At the same time, this setting method is convenient for the connection of the first sub-resonator 210 and the second sub-resonator 220 in the process, as well as the calculation and preparation of the effective working area.

[0063] The technical solution of the embodiment of the present utility model, by setting three sub-resonators, the second sub-resonator is connected in parallel with one of the first sub-resonators, and the effective working areas of each first sub-resonator are the same, which avoids the overall impedance of the filter being too large and affecting the working performance, and ensures the suppression effect of non-linear components.

[0064] Optionally, continue to refer to Figure 3 and Figure 4 As shown, both the first sub-resonator 210 and the second sub-resonator 220 include a connection structure 23; the connection structure 23 penetrates the piezoelectric layer and connects the top electrode layer 32 of the first sub-resonator 210 and the bottom electrode layer 31 of the second sub-resonator 220 or connects the bottom electrode layer 31 of the first sub-resonator 210 and the top electrode layer 32 of the second sub-resonator 220.

[0065] Among them, the connection structure 23 can be used to connect the bottom electrode layer 31 and the top electrode layer 32 to realize the series connection between sub-resonators. In order to ensure the parallel connection between adjacent first sub-resonators 210 and second sub-resonators 220, through holes need to be prepared on the piezoelectric layer, and the position of the through holes determines the position of the connection structure 23, so that the prepared connection structure 23 penetrates the piezoelectric layer to connect the top electrode layer 32 of the first sub-resonator 210 and the bottom electrode layer 31 of the second sub-resonator 220 or connects the bottom electrode layer 31 of the first sub-resonator 210 and the top electrode layer 32 of the second sub-resonator 220.

[0066] Specifically, the connection structure 23 of the first sub-resonator 210 connects the top electrode layer 32 of the first sub-resonator 210 and the bottom electrode layer 31 of the second sub-resonator 220, and the connection structure 23 of the second sub-resonator 220 connects the bottom electrode layer 31 of the first sub-resonator 210 and the top electrode layer 32 of the second sub-resonator 220, that is, the parallel connection of the first sub-resonator 210 and the second sub-resonator 220 is completed.

[0067] In some embodiments, in order to simplify the process flow, the via holes can be prepared after the piezoelectric layer is prepared, and the connection structure 23 is prepared while preparing the top electrode layer 32 after the via holes are prepared, that is, the connection structure 23 and the top electrode layer 32 are prepared in the same process flow, ensuring the connection between the top electrode layer 32 and the bottom electrode layer 31.

[0068] The technical solution of the embodiment of the present invention connects the first sub-resonator and the second sub-resonator in parallel by setting a connection structure between the top electrode layer and the bottom electrode layer, ensuring the normal operation of the filter.

[0069] Optionally, continuing to refer to Figure 4 As shown, the connection structure 23 of the first sub-resonator 210 includes at least two; and / or, the connection structure 23 of the second sub-resonator 220 includes at least two.

[0070] Among them, since the connection structures 23 on each sub-resonator are connected in the same way, at least two connection structures 23 are provided on the first sub-resonator 210; and / or, at least two connection structures 23 are provided on the second sub-resonator 220. In the parallel connection relationship between the first sub-resonator 210 and the second sub-resonator 220, due to the setting of multiple connection structures 23, the impedance after the parallel connection of the first sub-resonator 210 and the second sub-resonator 220 can be made smaller, thereby optimizing the overall performance of the filter.

[0071] It can be understood that, in order to ensure the parallel connection of the first sub-resonator 210 and the second sub-resonator 220, at least one connection structure 23 is provided in the first sub-resonator 210, and at least one connection structure 23 is provided in the second sub-resonator 220. In order to further reduce the impedance after the parallel connection of the first sub-resonator 210 and the second sub-resonator 220, the connection structure 23 can be increased in the first sub-resonator 210 and / or the second sub-resonator 220, so that the impedance of the connected first sub-resonator 210 and second sub-resonator 220 is reduced, further optimizing the overall performance of the filter.

[0072] Optionally, continuing to refer to Figure 1 As shown, one end of the second resonator 2 is electrically connected to the adjacent first resonator 1, and the other end is grounded.

[0073] Among them, the second resonator 2 can be connected in parallel with the first resonator 1. One end of the second resonator 2 is electrically connected to the adjacent first resonator 1, and the other end is grounded.

[0074] Specifically, the second resonator 2 is set while ensuring that the filtering frequency range of the filter remains unchanged. Therefore, one of the third resonators 3 in the filter can be replaced by the second resonator 2, and the impedance of the second resonator 2 is equal to the impedance of the replaced resonator, thereby ensuring that the working performance of the filter does not change.

[0075] Optionally, Figure 7 is a schematic diagram of the circuit connection of the third filter provided by the embodiment of the present invention. As Figure 7 shown, the second resonator 2 is serially arranged between the signal input end of the filter and the first resonator 1.

[0076] Among them, since the first resonator 1 is serially arranged, the first resonator 1 serially arranged starting from the signal input end gradually shares the power of the signal input at the signal input end. However, the non-linear component has existed since it is input at the signal input end, and the amplitude of the non-linear signal without the power shared by the first resonator 1 is the largest. In the embodiment of the present invention, the second resonator 2 is arranged between the signal input end of the filter and the first resonator 1, which can cancel or weaken the influence of the non-linear component on the filter when the amplitude of the non-linear signal is the largest, and further improves the working performance of the filter.

[0077] The technical solution of the embodiment of the present invention is to set a first sub-resonator group and a second sub-resonator group in parallel in the filter. The first sub-resonator group includes at least two first sub-resonators serially arranged, and the second sub-resonator group includes at least one second sub-resonator. The effective working area of the first sub-resonator group and the second sub-resonator group is approximately the same, which weakens or eliminates the influence of the non-linear component while ensuring the normal working performance of the filter. Compared with two parallel sub-resonators, the second resonator in the embodiment of the present invention has a larger adjustable space, which can reduce the setting difficulty of the second resonator and improve the suppression effect of the non-linear component; the series connection of multiple sub-resonators can also reduce the power of the non-linear signal and further weaken the influence of the non-linear component on the filter.

[0078] The above specific implementation manners do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A filter, characterized in that, Comprising: At least two first resonators connected in series; Further comprising a second resonator, which is connected in parallel or in series with the first resonator; The second resonator comprises a first sub-resonator group and a second sub-resonator group arranged in parallel; The first sub-resonator group comprises at least two first sub-resonators, and at least two of the first sub-resonators in the same first sub-resonator group are connected in series; the second sub-resonator group comprises at least one second sub-resonator; The sum S1 of the effective working area areas of at least two of the first sub-resonators in the first sub-resonator group and the sum S2 of the effective working area areas of at least one of the second sub-resonators in the second sub-resonator group satisfy 2. The filter according to claim 1, characterized in that, A common bottom electrode layer is shared between at least two of the first sub-resonators in the same first sub-resonator group, and the top electrode layers are not connected to each other.

3. The filter according to claim 1, characterized in that, At least two of the first sub-resonators in the same first sub-resonator group are connected in series through one of the second sub-resonators.

4. The filter according to claim 1, wherein The first resonator group comprises two of the first sub-resonators; the second sub-resonator group comprises one of the second sub-resonators; The second sub-resonator is connected in parallel with one of the first sub-resonators; the first sub-resonators are connected in series; the effective working area of each first sub-resonator is the same.

5. The filter according to claim 1, wherein The first sub-resonator group comprises two of the first sub-resonators; the second sub-resonator group comprises one of the second sub-resonators; The second sub-resonator is connected in parallel with each of the first sub-resonators; the effective working area of each first sub-resonator is the same.

6. The filter according to claim 1, characterized in that, Both the first sub-resonator and the second sub-resonator comprise connection structures; the connection structures penetrate through the piezoelectric layer to connect the top electrode layer of the first sub-resonator and the bottom electrode layer of the second sub-resonator or to connect the bottom electrode layer of the first sub-resonator and the top electrode layer of the second sub-resonator.

7. The filter according to claim 6, wherein The connection structure of the first sub-resonator comprises at least two; and / or, the connection structure of the second sub-resonator comprises at least two.

8. The filter according to claim 1, wherein One end of the second resonator is electrically connected to the adjacent first resonator, and the other end is grounded.

9. The filter according to claim 1, wherein The second resonator is connected in series between the signal input end of the filter and the first resonator.

10. The filter according to claim 1, characterized in that, The filter further comprises a third resonator; The third resonator is connected in parallel between adjacent first resonators.

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