An acoustic wave filter, a method of improving the performance thereof, a multiplexer, and an electronic device

Abstract

The embodiment of the present application discloses a kind of acoustic wave filters, filter includes multiple resonators and the sealing ring around the periphery of multiple resonators, multiple resonators include at least two series resonators and at least two parallel resonators, specified section of sealing ring is grounded, wherein, the sealing ring on the side of target series resonator is as the specified section of sealing ring, target series resonator satisfies the following conditions: the number of target series resonator is greater than or equal to 50% of the number of series resonators in filter, one side of target series resonator is close to sealing ring and there is no parallel resonator between one side of target series resonator and sealing ring.The embodiment of the present application also discloses a kind of method for improving the performance of acoustic wave filter, a multiplexer and an electronic device.The present application can solve the problem of unequal potential of sealing ring by grounding the specified section of sealing ring, avoid the coupling between series resonators, improve the out-of-band rejection and isolation.

Description

Technical Field

[0001] This invention relates to the field of filter technology, and more specifically, to an acoustic filter and a method for improving its performance, a multiplexer, and an electronic device. Background Technology

[0002] In acoustic filters, a sealing ring structure is usually added. On the one hand, it is used to encapsulate the resonator structure in the filter between two wafers to avoid the external physical environment from affecting the structure of the internal resonator. On the other hand, it forms an isolation structure to prevent adverse electrical coupling between the internal resonator and the outside, which would degrade the filter performance.

[0003] In filter structures, to achieve electrical coupling isolation, the sealing ring structure needs to be grounded. Typically, one of the filter's ground pins is connected to the sealing ring. Connecting multiple ground pins to the sealing ring can cause drift in the filter's transmission zero. However, when only one ground pin is connected to the sealing ring, the sealing ring is not at an ideal equipotential, creating a strong coupling path between resonators, which severely degrades the filter's out-of-band rejection performance. This deterioration is particularly pronounced when coupling occurs between series resonators. Summary of the Invention

[0004] The purpose of this invention is to provide an acoustic filter and a method, multiplexer and electronic device for improving its performance. By grounding a designated section of the sealing ring, the problem of unequal potential of the sealing ring can be solved, coupling between series resonators can be avoided, and out-of-band suppression and isolation can be improved.

[0005] This invention provides an acoustic wave filter, which includes multiple resonators and a sealing ring surrounding the multiple resonators. The multiple resonators include at least two series resonators and at least two parallel resonators.

[0006] A designated segment of the sealing ring is grounded, wherein the designated segment of the sealing ring is located on one side of the target series resonator, and the target series resonator satisfies the following condition:

[0007] The number of the target series resonators is greater than or equal to 50% of the number of series resonators in the filter. One side of the target series resonator is close to the sealing ring and there are no parallel resonators located between one side of the target series resonator and the sealing ring.

[0008] As a further improvement of the present invention, when one side of all series resonators in the filter is close to the sealing ring and no parallel resonator is located between one side of all series resonators and the sealing ring, the sealing ring located on one side of all series resonators is designated as a segment of the sealing ring.

[0009] As a further improvement of the present invention, when the specified segment of the sealing ring is greater than 1, at least one specified segment of the sealing ring is grounded.

[0010] As a further improvement of the invention, a designated section of the sealing ring is grounded via at least one grounding pin.

[0011] As a further improvement of the present invention, the filter includes an existing ground pin, the number of which is greater than or equal to 1.

[0012] The designated segment of the sealing ring is grounded through at least one existing grounding pin and / or at least one additional grounding pin.

[0013] This invention also provides a method for improving the performance of an acoustic filter, wherein the filter includes a plurality of resonators and a sealing ring surrounding the plurality of resonators, and the plurality of resonators includes at least two series resonators and at least two parallel resonators.

[0014] The method includes:

[0015] When the number of target series resonators is greater than or equal to 50% of the number of series resonators in the filter, and one side of the target series resonator is close to the sealing ring and no parallel resonator is located between one side of the target series resonator and the sealing ring, the sealing ring located on one side of the target series resonator is designated as the designated segment of the sealing ring, and the designated segment of the sealing ring is grounded.

[0016] As a further improvement of the present invention, when one side of all series resonators in the filter is close to the sealing ring and no parallel resonator is located between one side of all series resonators and the sealing ring,

[0017] The method includes:

[0018] The sealing ring located on one side of all series resonators is designated as the segment of the sealing ring, and the designated segment of the sealing ring is grounded.

[0019] As a further improvement of the present invention, when the designated segment of the sealing ring is greater than 1, at least one designated segment of the sealing ring is grounded.

[0020] As a further improvement of the invention, a designated section of the sealing ring is grounded via at least one grounding pin.

[0021] As a further improvement of the present invention, the filter includes an existing ground pin, the number of which is greater than or equal to 1.

[0022] The designated segment of the sealing ring is grounded via at least one existing grounding pin and / or at least one additional grounding pin.

[0023] This invention also provides a multiplexer, which includes the aforementioned filter.

[0024] This invention also provides a communication device, which includes the aforementioned filter.

[0025] The beneficial effects of this invention are as follows:

[0026] By grounding a designated section of the sealing ring, the problem of unequal sealing ring potentials can be solved, coupling between series resonators can be avoided, and out-of-band rejection and isolation can be improved. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of an acoustic filter according to an exemplary embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of another acoustic filter according to an exemplary embodiment of the present invention;

[0030] Figure 3 for Figure 1 and Figure 2 The diagram shows the equivalent topology of the acoustic filter.

[0031] Figure 4 This is a schematic diagram of the equivalent topology of the electrical coupling generated by the sealing ring described in the exemplary comparative example.

[0032] Figure 5 A schematic diagram of the equivalent topology of electrical coupling generated by the sealing ring according to an exemplary embodiment;

[0033] Figure 6 for Figure 4 and Figure 5 A comparative diagram of out-of-band suppression. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0036] Furthermore, the terminology used in the description of this invention is for illustrative purposes only and is not intended to limit the scope of the invention. The terms "comprising" and / or "including" are used to specify the presence of said elements, steps, operations, and / or components, but do not exclude the presence or addition of one or more other elements, steps, operations, and / or components. The terms "first," "second," etc., may be used to describe various elements, do not represent an order, and do not limit these elements. Moreover, in the description of this invention, unless otherwise stated, "a plurality of" means two or more. These terms are used only to distinguish one element from another. These and / or other aspects become apparent in conjunction with the following drawings, and those skilled in the art will more readily understand the description of the embodiments of the invention. The drawings are used for illustrative purposes only to depict the embodiments of the invention. Those skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods shown in the invention can be employed without departing from the principles of the invention.

[0037] An acoustic wave filter according to an embodiment of the present invention includes a plurality of resonators and a sealing ring surrounding the plurality of resonators. The plurality of resonators includes at least two series resonators and at least two parallel resonators.

[0038] A designated segment of the sealing ring is grounded, wherein the designated segment of the sealing ring is located on one side of the target series resonator, and the target series resonator satisfies the following condition:

[0039] The number of the target series resonators is greater than or equal to 50% of the number of series resonators in the filter. One side of the target series resonator is close to the sealing ring and there are no parallel resonators located between one side of the target series resonator and the sealing ring.

[0040] The present invention proposes an acoustic filter in which a designated section of the sealring is grounded. The designated section of the sealring is adaptively determined according to the position of each series resonator in the acoustic filter. By changing the grounding position of the sealring and increasing the number of grounding points, the problem of unequal potentials in the designated section of the sealring can be solved, coupling between the series resonators can be avoided, the isolation can be improved, and the out-of-band rejection performance of the filter can be improved.

[0041] It is understandable that the target series resonator is a combination of multiple series resonators arranged adjacent to each other, for example... Figure 1 The series resonators S1 to S3 in the target series resonator must meet the following conditions: 1) their number is half or more of the total number of series resonators; 2) one side is entirely close to the sealing ring; 3) there are no parallel resonators between the side close to the sealing ring and the sealing ring. When the above conditions are met, the sealing ring on one side of the target series resonator is designated as the sealing ring segment, and this segment of the sealing ring is grounded.

[0042] An acoustic filter is a multi-layered structure. Multiple resonators exist between the input and output terminals of the filter, consisting of multiple series resonators and multiple parallel resonators. Each resonator may include, but is not limited to, multiple layers such as a substrate, an acoustic mirror cavity and a bottom electrode, a piezoelectric layer, and a top electrode. It may also include one or more of the following layers: a temperature compensation layer, a mass loading layer, a protective layer (passivation layer), and a sacrificial layer. This invention does not specifically limit the layer structure of each resonator.

[0043] Understandably, when coupling occurs between the input and output of an acoustic filter, it significantly impacts the filter's out-of-band rejection (OBS). The farther apart the coupling points (i.e., the series resonators causing the coupling) are, the greater the impact on OBS. When only a few series resonators in the acoustic filter are close to the sealing ring on one side, and there are no parallel resonators between this side and the sealing ring, the coupling generated through the sealing ring has a relatively small impact on the acoustic filter's performance. For example... Figure 1 The positions of the series resonators S1 to S5 span a considerable distance, significantly impacting out-of-band suppression. And when... Figure 1When only a small number of series resonators (e.g., only series resonators S1 and S2) are located near the sealring on one side, and there are no parallel resonators between these series resonators and the sealring, the coupling generated by the sealring has a relatively small impact on the acoustic filter. Therefore, the filter of this invention specifies that when at least 50% of the series resonators in the filter are located near the sealring on one side, and at least 50% of the series resonators are located without parallel resonators between them and the sealring on one side, this portion of the series resonators is used as the target series resonator, and this section of the sealring needs to be directly grounded. This section of the sealring resolves the issue of unequal potentials, reduces coupling between series resonators, and improves out-of-band rejection.

[0044] In one optional implementation, when one side of all series resonators in the filter is close to the sealing ring and no parallel resonator is located between one side of all series resonators and the sealing ring, the sealing ring located on one side of all series resonators is designated as a segment of the sealing ring.

[0045] In an acoustic filter, there may be a situation where one side of all series resonators is close to the sealring, and there are no parallel resonators between this side of any series resonator and the sealring. In this case, all series resonators are the target series resonators (e.g., Figure 2 The series resonators S1 to S5 are connected in series, so the sealring on this side of all series resonators is directly grounded. This section of the sealring can also solve the problem of unequal potentials, reduce the coupling between all series resonators, and improve out-of-band rejection.

[0046] In one alternative implementation, when a designated segment of the sealing ring is greater than 1, at least one designated segment of the sealing ring is grounded.

[0047] It should be noted that, due to differences in the number and placement of resonators in the filter, the number of specified segments of the sealing ring that meet the conditions may be greater than one. When the number of specified segments is greater than one, one of the specified segments, a portion of the specified segments, or all of the specified segments can be grounded. This invention does not specifically limit the number of specified segments that meet the conditions that are grounded. For example... Figure 1 In this process, the number of specified segments of the sealing ring that meet the conditions is 2 (the upper sealing ring of series resonators S1, S2, and S3, and the lower sealing ring of series resonators S3, S4, and S5). One or both of the two specified segments can be grounded.

[0048] In one alternative implementation, a designated segment of the sealing ring is grounded via at least one grounding pin.

[0049] In one optional implementation, the filter includes an existing ground pin, the number of which is greater than or equal to one.

[0050] The designated segment of the sealing ring is grounded through at least one existing grounding pin and / or at least one additional grounding pin.

[0051] When grounding a designated section of the sealing ring, grounding is achieved through a grounding pad (pin) and a corresponding via (the via is fabricated on the grounding pad). This is a preferred implementation. Grounding can also be achieved through a grounding pad or other methods. It is understood that the acoustic filter already has grounding pins, and an existing grounding pad (e.g.) can be utilized. Figure 1 One or more of the grounding pins (G1 to G4) in the filter can be grounded. Alternatively, a new grounding pad can be added, meaning a separate grounding pad can be used, with the number of new grounding pads being greater than or equal to one. Grounding can also be performed using both existing and new grounding pads. When grounding, one or more grounding pads can be selected based on the structural adaptability of the acoustic filter.

[0052] The structure of the filter described in this invention will be explained below through specific embodiments.

[0053] like Figure 1 As shown, an example of an acoustic wave filter is provided, which consists of five series resonators S1 to S5 connected in series and four parallel resonators P1 to P4 connected in parallel. This includes ground pads G1 to G4 for one end (ground end) of each of the four parallel resonators P1 to P4. One end of each of the parallel resonators (P1 to P4) can also be grounded through the same ground pad. Figure 1 For illustrative purposes only, there is no limit to the number of series and parallel resonators, nor to the number and connection of grounding pads. Figure 1 The connection relationship between multiple resonators is not shown in the figure. The connecting lines between the resonators are omitted and only their relative positions are shown. Figure 1 The area surrounding the center is the seal ring. The seal ring has a certain width to ensure the reliability of the seal, and it also needs to be a certain distance from the internal resonator to isolate the internal resonator from the external environment.

[0054] from Figure 1As can be seen, the upper side of series resonators S1, S2, and S3 is close to the sealring, and there are no parallel resonators located between the upper side of series resonators S1, S2, and S3 and the sealring. The number of series resonators meeting this condition is 3, which is greater than 50% of the total number of series resonators (5). Therefore, series resonators S1 to S3 are used as target series resonators. The sealring on the upper side of the target series resonators (i.e., series resonators S1, S2, and S3) is grounded through a grounding pad and its corresponding through-hole. One or more grounding pads from G1 to G4 can be selected to ground this section of the sealring, or one or more additional grounding pads can be added to ground this section of the sealring.

[0055] The lower sides of series resonators S3, S4, and S5 are close to the sealring, and there are no parallel resonators located between the lower sides of series resonators S3, S4, and S5 and the sealring. The number of series resonators meeting this condition is 3, which is greater than 50% of the total number of series resonators (5). Therefore, series resonators S3 to S5 are selected as the target series resonators. The sealring on the lower side of the target series resonators (series resonators S3, S4, and S5) is grounded through a grounding pad and its corresponding through-hole. One or more grounding pads from G1 to G4 can be selected to ground this section of the sealring, or one or more additional grounding pads can be added to ground this section of the sealring.

[0056] Alternatively, the upper sealring of series resonators S1, S2, and S3 can be grounded, the lower sealring of series resonators S3, S4, and S5 can be grounded, or both the upper sealring of series resonators S1, S2, and S3 and the lower sealring of series resonators S3, S4, and S5 can be grounded simultaneously.

[0057] like Figure 2 As shown, another acoustic filter is illustrated, which is similar to... Figure 1 The difference in the acoustic filter shown is that the upper sides of the series resonators S1 to S5 are all close to the sealring, and there are no parallel resonators located between the upper sides of the series resonators S1 to S5 and the sealring. Therefore, the sealring on the upper side of the series resonators S1 to S5 is grounded through the grounding pad and the corresponding through-hole. One or more grounding pads can be selected from G1 to G4 to ground this section of the sealring, or one or more additional grounding pads can be added to ground this section of the sealring.

[0058] like Figure 3 As shown, Figure 1 and 2The equivalent topology of the acoustic filter shown illustrates the connection configuration of the series resonators, parallel resonators, and ground inductor, wherein the number of both series and parallel resonators is greater than or equal to two. It should be noted that variations in the connection configuration of the series resonators, parallel resonators, and ground inductor do not affect the structure of the filter described in this invention.

[0059] like Figure 4 As shown, Figure 2 The diagram illustrates the equivalent topology of electrical coupling generated by the sealring of the acoustic filter, where the sealring is grounded via G1. Due to the presence of the sealring, there is a certain distance between the sealring and the input (IN) and output (OUT) terminals of the acoustic filter, resulting in parasitic inductance and capacitance. Furthermore, the grounding location is far from the series resonators, meaning the sealring is not an ideal ground and the potentials on the sealring are unequal. Feedthrough paths exist between the multiple series resonators, and the resulting coupling significantly degrades the performance of the acoustic filter.

[0060] like Figure 5 As shown, Figure 2 The acoustic filter shown uses the structure proposed in this invention (with a designated segment of the sealring grounded), resulting in an equivalent electrical coupling topology for the sealring. The example illustrates a designated segment of the sealring grounded via G1. From... Figure 5 As can be seen, multiple grounding points are formed near the series resonators. Through these grounding points, the potential of each segment of the sealring (i.e., the designated section of the sealring) above the series resonators is close to the same potential, preventing the transmission of feedthrough signals. Therefore, no feedthrough path can be formed between the multiple series resonators, avoiding coupling between them. By grounding the designated section of the seal ring using the structure of the acoustic filter proposed in this invention, the potential between multiple equivalent inductances (parasitic inductances) can be eliminated, leaving only parasitic capacitance. The presence of these parasitic capacitances also prevents the formation of a feedthrough path between the multiple series resonators; therefore, the parasitic capacitances do not affect the structure of the acoustic filter proposed in this invention.

[0061] like Figure 6 As shown, an embodiment of the present invention is illustrated. Figure 5 The equivalent topology of the acoustic filter shown is (i.e., the sealring on one side of the series resonator is grounded) and the comparative example ( Figure 4 The diagram shows a comparison of out-of-band suppression for the equivalent topology of the acoustic filter (i.e., without grounding the sealring on the series resonator side). The solid line represents the out-of-band suppression curve corresponding to the embodiment of the invention, while the dashed line represents the out-of-band suppression curve corresponding to the comparative model. From... Figure 6As can be seen, the out-of-band suppression of the embodiments of the present invention is improved to varying degrees in the ranges of 3.0G-3.3G and 3.7G-4G. Specifically, the transmission zero point near the right side drifts to around 3.7G, thereby ensuring improved suppression above 3.7G, especially in the 3.7G-4G range. The transmission zero point near the left side drifts to around 3.0G, thereby ensuring improved suppression above 3.0G, especially in the 3.0G-3.3G range.

[0062] An embodiment of the present invention provides a method for improving the performance of an acoustic wave filter. The filter includes multiple resonators and a sealing ring surrounding the multiple resonators. The multiple resonators include at least two series resonators and at least two parallel resonators.

[0063] The method includes:

[0064] When the number of target series resonators is greater than or equal to 50% of the number of series resonators in the filter, and one side of the target series resonator is close to the sealing ring and no parallel resonator is located between one side of the target series resonator and the sealing ring, the sealing ring located on one side of the target series resonator is designated as the designated segment of the sealing ring, and the designated segment of the sealing ring is grounded.

[0065] In one alternative implementation, when one side of all series resonators in the filter is close to the sealing ring and no parallel resonators are located between one side of all series resonators and the sealing ring,

[0066] The method includes:

[0067] The sealing ring located on one side of all series resonators is designated as the segment of the sealing ring, and the designated segment of the sealing ring is grounded.

[0068] In one alternative implementation, when a designated segment of the sealing ring is greater than 1, at least one designated segment of the sealing ring is grounded.

[0069] In one alternative implementation, a designated section of the sealing ring is grounded via at least one grounding pin.

[0070] In one optional implementation, the filter includes an existing ground pin, the number of which is greater than or equal to one.

[0071] The designated segment of the sealing ring is grounded via at least one existing grounding pin and / or at least one additional grounding pin.

[0072] An embodiment of the present invention provides a multiplexer, which includes the filter described in the foregoing embodiments.

[0073] The present invention provides a communication device, which includes the filter described in the foregoing embodiments.

[0074] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0075] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0076] Those skilled in the art will understand that although the invention has been described with reference to exemplary embodiments, various changes may be made and its elements may be substituted with equivalents without departing from the scope of the invention. Furthermore, many modifications may be made to adapt particular situations or materials to the teachings of the invention without departing from the essential scope of the invention. Therefore, the invention is not limited to the specific embodiments disclosed, but rather the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An acoustic wave filter, the filter comprising a plurality of resonators and a sealing ring surrounding the plurality of resonators, characterized in that, The plurality of resonators includes at least two series resonators and at least two parallel resonators. A designated segment of the sealing ring is grounded via at least one grounding pin, wherein the sealing ring located on one side of the target series resonator is designated as the designated segment of the sealing ring, and the target series resonator satisfies the following condition: The number of the target series resonators is greater than or equal to 50% of the number of series resonators in the filter, and one side of the target series resonator is close to the sealing ring and there are no parallel resonators located between the side of the target series resonator and the sealing ring; When one side of all series resonators in the filter is close to the sealing ring and no parallel resonator is located between one side of all series resonators and the sealing ring, the sealing ring located on one side of all series resonators is designated as the segment of the sealing ring.

2. The filter as claimed in claim 1, wherein, When the specified segment of the sealing ring is greater than 1, at least one specified segment of the sealing ring is grounded.

3. The filter as described in claim 1, wherein, The filter includes an existing ground pin, and the number of the existing ground pins is greater than or equal to 1. The designated segment of the sealing ring is grounded through at least one existing grounding pin and / or at least one additional grounding pin.

4. A method for improving the performance of an acoustic wave filter, the filter comprising a plurality of resonators and a sealing ring surrounding the plurality of resonators, characterized in that, The plurality of resonators includes at least two series resonators and at least two parallel resonators. The method includes: When the number of target series resonators is greater than or equal to 50% of the number of series resonators in the filter, and one side of the target series resonator is close to the sealing ring and there is no parallel resonator located between one side of the target series resonator and the sealing ring, the sealing ring located on one side of the target series resonator is designated as the designated segment of the sealing ring, and the designated segment of the sealing ring is grounded through at least one grounding pin. When one side of all series resonators in the filter is close to the sealing ring and no parallel resonator is located between one side of all series resonators and the sealing ring, the sealing ring located on one side of all series resonators is designated as the designated segment of the sealing ring, and the designated segment of the sealing ring is grounded.

5. The method of claim 4, wherein, When the specified segment of the sealing ring is greater than 1, at least one specified segment of the sealing ring is grounded.

6. The method of claim 4, wherein, The filter includes an existing ground pin, and the number of the existing ground pins is greater than or equal to 1. The designated segment of the sealing ring is grounded via at least one existing grounding pin and / or at least one additional grounding pin.

7. A multiplexer, characterized in that, The multiplexer includes the filter according to any one of claims 1-3.

8. A communication device, characterized in that, The communication device includes the filter according to any one of claims 1-3.

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