Elastic wave filter, radio frequency module and electronic equipment
By introducing an Nth-order longitudinal coupling filter and isolation unit into the elastic wave filter, the miniaturization and out-of-band suppression compatibility issues were resolved, achieving both size reduction and performance improvement of the filter.
Patent Information
- Application Number
- CN202520514844.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-21
- Publication Date
- 2026-03-06
- Estimated Expiration
- 2035-03-21
AI Technical Summary
How to achieve miniaturization of elastic wave filters without affecting their out-of-band rejection performance, especially avoiding deterioration of out-of-band rejection when reducing the number of resonators.
Design an elastic wave filter comprising a substrate, multiple series and parallel resonators, an Nth-order longitudinally coupled filter, and an isolation unit. The resonant frequency of the isolation unit is located outside the passband of the filter and is placed in the gap to provide isolation band suppression without increasing the chip area.
Miniaturization of elastic wave filters has been achieved while maintaining or improving out-of-band rejection performance without increasing insertion loss, thus meeting stringent requirements for insertion loss and out-of-band rejection.
Smart Images
Figure CN223978630U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of filter technology, and in particular to an elastic wave filter, a radio frequency module, and an electronic device. Background Technology
[0002] Elastic wave filters are filters that utilize the propagation characteristics of elastic waves (such as surface acoustic waves) in a specific medium to achieve signal processing, playing a crucial role in communication equipment. However, with the trend towards miniaturization in communication equipment, the miniaturization of elastic wave filters has also become an inevitable trend.
[0003] Typically, to achieve miniaturization, elastic wave filters reduce the order of the resonators, i.e., reduce the number of resonators in the filter. However, this leads to a deterioration in the out-of-band rejection of the elastic wave filter. Therefore, how to achieve miniaturization of elastic wave filters without compromising their out-of-band rejection has become a key issue for those skilled in the art. Utility Model Content
[0004] In view of this, this application provides an elastic wave filter, an RF module, and an electronic device. This elastic wave filter facilitates miniaturization of the elastic wave filter without compromising its out-of-band rejection. The solution is as follows:
[0005] An elastic wave filter, comprising:
[0006] Substrate;
[0007] Multiple resonators are located on the substrate, including multiple series resonators and multiple parallel resonators; the multiple series resonators are sequentially connected in series in a first path, and the multiple parallel resonators are connected in a second path; at least one of the first and second ends of the series resonators is grounded through the parallel resonator; the first end of the series resonator is electrically connected to the input end of the elastic wave filter, and the second end is electrically connected to the output end of the elastic wave filter.
[0008] An N-order longitudinal coupling filter, where N is an odd number not less than 3, is disposed in the first path and along the first direction. The input terminal of the N-order longitudinal coupling filter is electrically connected to the second terminal of the series resonator in front, and the output terminal is electrically connected to the first terminal of the series resonator behind. The first direction is parallel to the plane where the substrate is located and extends along the first path from the input terminal of the elastic wave filter to the output terminal. The input terminal of the N-order longitudinal coupling filter is grounded through the first ground terminal on the side where the output terminal is located, and the output terminal is grounded through the second ground terminal on the side where the input terminal is located.
[0009] An isolation unit is electrically connected to at least one of a first gap and a second gap, wherein the first gap is the gap between the input terminal of the Nth-order longitudinal coupling filter along the first direction and the second ground terminal, and the second gap is the gap between the output terminal of the Nth-order longitudinal coupling filter along the first direction and the first ground terminal;
[0010] The resonant frequency of the isolation unit is located outside the passband of the elastic wave filter, but within the isolation band of the elastic wave filter.
[0011] Optionally, the isolation unit is an interdigitated capacitor; or
[0012] The isolation unit is a resonator.
[0013] Optionally, the plurality of series resonators include a first series resonator and a second series resonator, and the plurality of parallel resonators include a first parallel resonator and a second parallel resonator;
[0014] The first series resonator is closer to the input terminal of the elastic wave filter than the second series resonator. The first parallel resonator is electrically connected between the first terminal of the first series resonator and the input terminal of the elastic wave filter. The second parallel resonator is electrically connected between the second terminal of the second series resonator and the output terminal of the elastic wave filter.
[0015] The N-order longitudinal coupling filter is located between the first series resonator and the second series resonator. The input terminal of the N-order longitudinal coupling filter is electrically connected to the second terminal of the first series resonator, and the output terminal is electrically connected to the first terminal of the second series resonator.
[0016] Optionally, the Nth-order longitudinal coupling filter includes N coupling units arranged along the second direction, wherein the N coupling units include m first coupling units and n second coupling units, where m≥1, n≥1, and m+n=N; the second direction is parallel to the plane of the substrate and perpendicular to the first direction;
[0017] The first coupling unit and the second coupling unit are arranged alternately along the second direction, and along the first direction, the end of the first coupling unit near the front series resonator is electrically connected to the input terminal of the Nth order longitudinal coupling filter, and the end near the rear series resonator is electrically connected to the first ground terminal; the end of the second coupling unit near the rear series resonator is electrically connected to the output terminal of the Nth order longitudinal coupling filter, and the end near the front series resonator is electrically connected to the second ground terminal.
[0018] The first gap is the gap between the input end of the Nth-order longitudinal coupling filter along the first direction and the second ground end of the corresponding second coupling unit, and the second gap is the gap between the input end of the Nth-order longitudinal coupling filter along the first direction and the first ground end of the corresponding first coupling unit.
[0019] Optionally, N=3, and the Nth-order longitudinal coupling filter is a third-order longitudinal coupling filter; or
[0020] N=5, the Nth-order longitudinal coupling filter is a 5th-order longitudinal coupling filter; or
[0021] N=7, the Nth-order longitudinal coupling filter is a 7th-order longitudinal coupling filter; or
[0022] N=9, and the Nth-order longitudinal coupling filter is a 9th-order longitudinal coupling filter.
[0023] Optionally, the Nth-order longitudinal coupling filter is a 5th-order longitudinal coupling filter, and the N coupling units include 3 first coupling units and 2 second coupling units;
[0024] The first gap includes a first sub-gap corresponding to each of the three first coupling units, and the second gap includes a second sub-gap corresponding to each of the two second coupling units. The isolation unit is electrically connected to at least one of the first sub-gap and the second sub-gap.
[0025] Optionally, the isolation unit includes j first isolation units, 1≤j≤3, wherein the first isolation units are electrically connected to the first sub-gap; or
[0026] The isolation unit includes k second isolation units, where 1 ≤ k ≤ 2, and the second isolation units are electrically connected to the second sub-gap.
[0027] Optionally, the isolation unit includes j first isolation units and k second isolation units, where 1≤j≤3 and 1≤k≤2;
[0028] The first isolation unit is electrically connected to the first sub-gap, and the second isolation unit is electrically connected to the second sub-gap.
[0029] A radio frequency module comprising any of the above-mentioned elastic wave filters.
[0030] An electronic device comprising the aforementioned radio frequency module.
[0031] Compared with related technologies, the beneficial effects of the technical solution of this application are as follows:
[0032] The elastic wave filter includes: a substrate, multiple series resonators and multiple parallel resonators located on the substrate, an N-order longitudinal coupling filter connected in series between the multiple series resonators, and an isolation unit. The input terminal of the N-order longitudinal coupling filter is electrically connected to the second terminal of the series resonator in front of it, and the output terminal of the N-order longitudinal coupling filter is electrically connected to the first terminal of the series resonator behind it. The isolation unit is electrically connected to at least one of a first gap and a second gap. The first gap is the gap between the input terminal of the N-order longitudinal coupling filter and the second ground terminal along the first direction, and the second gap is the gap between the output terminal of the N-order longitudinal coupling filter and the first ground terminal along the first direction. The resonant frequency of the isolation unit is located outside the passband of the elastic wave filter but within its isolation band. Therefore, the elastic wave filter has an isolation unit that can suppress its isolation band. Furthermore, the isolation unit, located in at least one of the first and second gaps, does not require additional chip area, which is beneficial for the miniaturization of the elastic wave filter and does not compromise its out-of-band suppression. Consequently, the elastic wave filter can have a smaller size and higher out-of-band suppression. Attached Figure Description
[0033] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0034] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.
[0035] Figure 1 A schematic diagram of the topology of an elastic wave filter provided in this application;
[0036] Figure 2 A schematic diagram of the layout of an elastic wave filter provided in this application;
[0037] Figure 3 This is a schematic diagram of the topological structure for comparison.
[0038] Figure 4 This is a schematic diagram of the map to scale.
[0039] Figure 5 A performance comparison diagram of an elastic wave filter provided in this application;
[0040] Figure 6 A performance comparison diagram of an elastic wave filter provided in this application;
[0041] Figure 7 A schematic diagram of another elastic wave filter provided in this application;
[0042] Figure 8 A schematic diagram of another elastic wave filter provided in this application;
[0043] Figure 9 A schematic diagram of another elastic wave filter provided in this application. Detailed Implementation
[0044] The embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely one area of this application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0045] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0046] As described in the background section, miniaturizing elastic wave filters by reducing the number of resonators leads to a deterioration in the out-of-band rejection of the elastic wave filters.
[0047] Typically, improving out-of-band rejection of filters involves increasing the order of the resonator. However, this leads to an increase in the chip area of the elastic filter, which contradicts the trend of miniaturization in elastic wave filters. This makes it impossible to achieve both miniaturization and out-of-band rejection in elastic wave filters, thus limiting their application and development.
[0048] In addition, for elastic wave filters, increasing the order of the resonator will also worsen the insertion loss of the elastic wave filter to a certain extent, making it difficult for the elastic wave filter to simultaneously meet the strict requirements of insertion loss and out-of-band suppression, which also limits the application and development of elastic wave filters.
[0049] Based on the above, this application provides an elastic wave filter, such as... Figure 1 and Figure 2 As shown, Figure 1 This is a schematic diagram of the topology of an elastic wave filter provided in this application. Figure 2This application provides a schematic diagram of an elastic wave filter, which includes:
[0050] Substrate 100 may be made of any one or more suitable materials, such as piezoelectric materials and semiconductor materials.
[0051] Multiple resonators are located on the substrate 100, including multiple series resonators 210 and multiple parallel resonators 220. The multiple series resonators 210 are sequentially connected in series in a first path. The multiple parallel resonators 220 are disposed in a second path. At least one of the first and second ends of the series resonators 210 is grounded through the parallel resonators 220. For example, the first end of the series resonator 210 can be grounded through the parallel resonator 220, or the second end of the series resonator 210 can be grounded through the parallel resonator 220, or both the first and second ends of the series resonator 210 can be grounded through different parallel resonators 220.
[0052] It should be noted that the first end of the series resonator 210 is electrically connected to the input terminal IN of the elastic wave filter, and the second end of the series resonator 210 is electrically connected to the output terminal OUT of the elastic wave filter. That is, the first end of each series resonator 210 is electrically connected to the input terminal IN of the elastic wave filter, and the second end of each series resonator 210 is electrically connected to the output terminal OUT of the elastic wave filter. For example, the first series resonator is the one closest to the input terminal IN of the elastic wave filter among the multiple series resonators 210, and the last series resonator is the one closest to the output terminal OUT of the elastic wave filter among the multiple series resonators 210, arranged sequentially. Then, the first end of the first series resonator is directly electrically connected to the input terminal IN of the elastic wave filter, and the second end of the last series resonator is directly electrically connected to the output terminal OUT of the elastic wave filter. The second end of the first series resonator is electrically connected to the output terminal OUT of the elastic wave filter through the second series resonator to the last series resonator. The first end of the last series resonator is electrically connected to the input terminal IN of the elastic wave filter through the penultimate series resonator to the first series resonator. The first end of any series resonator 210 other than the first and last series resonators is electrically connected to the input terminal IN of the elastic wave filter through the series resonator in front of it, and the second end is electrically connected to the output terminal OUT of the elastic wave filter through the series resonator behind it. That is to say, the multiple series resonators 210 are connected in series through the first and second ends of each series resonator and electrically connected between the input terminal IN and the output terminal OUT of the elastic wave filter.
[0053] The N-order longitudinal coupling filter 300, also known as the N-order longitudinal elastic wave coupling filter, is an odd number of not less than 3. The N-order longitudinal coupling filter 300 is disposed in the first path and along the first direction. The input terminal 1 of the N-order longitudinal coupling filter 300 is electrically connected to the second terminal of the series resonator 210 located in front of the N-order longitudinal coupling filter 300, and the output terminal 2 of the N-order longitudinal coupling filter 300 is electrically connected to the first terminal of the series resonator 210 located behind the N-order longitudinal coupling filter 300. In other words, the N-order longitudinal coupling filter 300 is disposed in the first path and connected in series between multiple series resonators 210.
[0054] It should be noted that the first direction is parallel to the plane where the substrate 100 is located, and extends along the first path from the input terminal IN of the elastic wave filter to the output terminal OUT. That is, the first direction is parallel to the mounting plane of the multiple series resonators 210, and is the direction from the first series resonator 210 to the last series resonator 210. In addition, the input terminal 1 of the N-order longitudinal coupling filter 300 is grounded through the first ground terminal 3 located on the side where the output terminal 2 is located, and the output terminal 2 of the N-order longitudinal coupling filter 300 is grounded through the second ground terminal 4 located on the side where the input terminal 1 is located. In other words, the input terminal 1 and the output terminal 2 of the N-order longitudinal coupling filter 300 are located on opposite sides, and the ground terminal corresponding to the input terminal 1 of the N-order longitudinal coupling filter 300 is located on the opposite side of the side where the input terminal 1 is located. Similarly, the ground terminal corresponding to the output terminal 2 of the N-order longitudinal coupling filter 300 is located on the opposite side of the side where the output terminal 2 is located.
[0055] An isolation unit 400 is electrically connected to at least one of a first gap L1 and a second gap L2. The first gap L1 is the gap between the input terminal 1 of the Nth-order longitudinal coupling filter 300 along the first direction and the second ground terminal 4. The second gap L2 is the gap between the output terminal 2 of the Nth-order longitudinal coupling filter 300 along the first direction and the first ground terminal 3. It should be noted that for the isolation unit 400 to be electrically connected to at least one of the first gap L1 and the second gap L2, the isolation unit 400 is electrically connected to the first gap L1 in that it is electrically connected to both the input terminal 1 and the second ground terminal 4; the isolation unit 400 is electrically connected to the second gap L2 in that it is electrically connected to both the output terminal 2 and the first ground terminal 3. In other words, the isolation unit 400 is arranged in series in the first path.
[0056] The resonant frequency of the aforementioned isolation unit 400 is located outside the passband of the elastic wave filter but within its isolation band. The isolation units 400 are arranged in series in the first path, allowing them to suppress frequencies near their resonant frequency within the elastic wave filter. Thus, the isolation unit 400 suppresses the isolation band of the elastic wave filter but does not affect its passband.
[0057] As described above, the elastic wave filter has an isolation unit 400 that can suppress its isolation frequency band, and the isolation unit 400 is disposed in at least one of the first gap L1 and the second gap L2. That is, the elastic wave filter provides an isolation unit 400 that suppresses the isolation frequency band in the gap between the input terminal 1 and the second ground terminal 4 of the Nth-order longitudinal coupling filter 300 and / or the gap between the output terminal 2 and the first ground terminal 3 of the Nth-order longitudinal coupling filter 300. Compared to Figure 3 and Figure 4 It can be seen that, Figure 3 and Figure 4 The diagrams show the circuit topology and layout of the elastic wave filter without the isolation unit 400. The isolation unit 400 in the elastic wave filter provided in this application is disposed in at least one of the first gap L1 and the second gap L2. No additional space is required for the isolation unit 400, that is, no additional chip area is required for the isolation unit 400. This is beneficial for the miniaturization of the elastic wave filter and does not impair the out-of-band rejection of the elastic wave filter. As a result, the elastic wave filter can be smaller in size and has higher out-of-band rejection.
[0058] In one embodiment of this application, for example Figure 5 and Figure 6 As shown, Figure 5 This is a performance comparison chart of the elastic wave filter provided in this application. Figure 6 for Figure 5 Enlarged view of the area within the dashed box. Figure 6 and Figure 5 Curve 1 and curve 2 represent the admittance curves of the elastic wave filter with and without isolation unit 400, respectively. Figure 5 Curve 3 represents the admittance curve of isolation unit 400. Figure 5 and Figure 6 The horizontal axis represents frequency (Frep), in GHz, and the vertical axis represents decibels (dB). According to Figure 5It can be seen that the passband of the elastic wave filter can be the B40 band, with a frequency range of 2300MHz to 2400MHz, and the isolation band can be the B41 band, with a frequency range of 2500MHz to 2700MHz. The resonant frequency of the isolation unit 400 is located outside the passband of the elastic wave filter and within the isolation band of the elastic wave filter, thus having a strong isolation and suppression effect on the isolation band. Compared with curve 2, the suppression of the isolation band is improved by 2dB.
[0059] In addition, according to Figure 6 As can be seen from m100, at 2.300GHz, the elastic wave filter with isolation unit 400 corresponds to -1.844dB, while the elastic wave filter without isolation unit 400 corresponds to -1.802dB. According to... Figure 6 As can be seen from m101, at 2.400 GHz, the elastic wave filter with isolation unit 400 corresponds to -2.189 dB, while the elastic wave filter without isolation unit 400 corresponds to -2.191 dB. According to... Figure 6 As shown in m93, at 2.466 GHz, the elastic wave filter with isolation unit 400 corresponds to -30.142 dB, while the elastic wave filter without isolation unit 400 corresponds to -28.508 dB. This demonstrates that the isolation unit 400 does not affect the passband of the elastic wave filter, but at 2.466 GHz, which is relatively close to the passband, the suppression capability is improved by approximately 1.6 dB. Therefore, the roll-off characteristic of the elastic wave filter provided in this application is also improved by approximately 1.6 dB, without causing a deterioration in the loss at the frequency conversion point of the elastic wave filter.
[0060] In summary, the elastic wave filter provided in this application can be miniaturized, has strong out-of-band suppression capability, and also has improved roll-off characteristics. That is, the elastic wave filter has a small size and good working performance.
[0061] In one embodiment of this application, the isolation unit 400 can be an interdigital capacitor or a resonator. Therefore, the resonant frequency of the isolation unit 400 can be adjusted by the pitch of the interdigital electrodes in the isolation unit 400, so that the resonant frequency of the isolation unit 400 is within the isolation band of the elastic wave filter, but as far away as possible from the passband band of the elastic wave filter, for example... Figure 5 As shown, this allows the isolation band to be suppressed without affecting the passband, thus ensuring the performance of the elastic wave filter.
[0062] In one embodiment of this application, such as Figure 1As shown, the multiple series resonators 210 include a first series resonator S1 and a second series resonator S2, and the multiple parallel resonators 220 include a first parallel resonator P1 and a second parallel resonator P2.
[0063] The first series resonator S1 is closer to the input terminal IN of the elastic wave filter than the second series resonator S2, meaning the first series resonator S1 and the second series resonator S2 are arranged sequentially along the first direction. The first parallel resonator P1 is electrically connected between the first terminal of the first series resonator S1 and the input terminal IN of the elastic wave filter, and the second parallel resonator P2 is electrically connected between the second terminal of the second series resonator S2 and the output terminal OUT of the elastic wave filter. In other words, the first series resonator S1 is grounded through the first parallel resonator P1, and the second series resonator S2 is grounded through the second parallel resonator P2.
[0064] The N-order longitudinal coupling filter 300 is located between the first series resonator S1 and the second series resonator S2. The input terminal 1 of the N-order longitudinal coupling filter 300 is electrically connected to the second terminal of the first series resonator S1, and the output terminal 2 of the N-order longitudinal coupling filter 300 is electrically connected to the first terminal of the second series resonator S2.
[0065] As can be seen from the above, the elastic wave filter provided in this application can have two series resonators 210 and two parallel resonators 220. The number is small, that is, the resonator order of the elastic wave filter is low, which can effectively reduce the size of the elastic wave filter and achieve miniaturization.
[0066] It should be noted that in the above embodiments, the number of series resonators 210 is two, and the number of parallel resonators 220 is two. However, this application does not limit this. In other embodiments of this application, the number of series resonators 210 can also be other, such as 3, 4, 5, or even more, etc., and the number of parallel resonators 220 varies with the number of series resonators 210. Simultaneously, the number of N-order longitudinal coupling filters 300 can also be at least two. When the number of N-order longitudinal coupling filters 300 is at least two, any N-order longitudinal coupling filter 300 is disposed between two adjacent series resonators 210. Alternatively, multiple N-order longitudinal coupling filters 300 can be connected in series and disposed between any two adjacent series resonators 210. Or, a portion of at least two N-order longitudinal coupling filters 300 can be connected in series and disposed between any two adjacent series resonators 210, while the other portion of any N-order longitudinal coupling filter 300 is disposed between two adjacent series resonators 210, etc. This application will not be elaborated further here, but as long as the isolation unit 400 is connected in series between the series resonator 210 and the Nth-order longitudinal coupling filter 300, any structural variation is within the scope of this application.
[0067] In one embodiment of this application, such as Figure 7 As shown, the N-order longitudinally coupled filter 300 includes N coupling units arranged along the second direction. The N coupling units include m first coupling units 311 and n second coupling units 312, where m ≥ 1, n ≥ 1, and m + n = N. The second direction is parallel to the plane of the substrate 100 and perpendicular to the first direction, that is, the first and second directions are parallel to the same plane and perpendicular to each other.
[0068] The first coupling unit 311 and the second coupling unit 312 are arranged alternately along the second direction. Along the first direction, one end of the series resonator 210 of the first coupling unit 311, near the front of the N-order longitudinal coupling filter 300, is electrically connected to the input terminal 1 of the N-order longitudinal coupling filter 300. One end of the series resonator 210 near the rear of the N-order longitudinal coupling filter 300 is electrically connected to the first ground terminal 3 of the N-order longitudinal coupling filter 300. One end of the series resonator 210 of the second coupling unit 312, near the rear of the N-order longitudinal coupling filter 300, is electrically connected to the output terminal 2 of the N-order longitudinal coupling filter 300. One end of the series resonator 210 near the front of the N-order longitudinal coupling filter is electrically connected to the second ground terminal 4 of the N-order longitudinal coupling filter.
[0069] The first gap L1 is the gap between the input terminal 1 of the Nth-order longitudinal coupling filter 300 along the first direction and the second ground terminal 4 of the corresponding second coupling unit 312, and the second gap L2 is the gap between the output terminal 2 of the Nth-order longitudinal coupling filter 300 along the first direction and the first ground terminal 3 of the corresponding first coupling unit 311, so that no additional space is needed to set up the isolation unit 400, which is beneficial to the miniaturization of the elastic wave filter.
[0070] In one embodiment of this application, N=3, meaning the Nth-order longitudinal coupling filter can be a 3rd-order longitudinal coupling filter; N=5, meaning the Nth-order longitudinal coupling filter can be a 5th-order longitudinal coupling filter; N=7, meaning the Nth-order longitudinal coupling filter can be a 7th-order longitudinal coupling filter; and N=9, meaning the Nth-order longitudinal coupling filter can be a 9th-order longitudinal coupling filter. However, this application does not limit this, and the aforementioned Nth-order longitudinal coupling filter can also be other higher-order longitudinal coupling filters, depending on the specific circumstances.
[0071] In one embodiment of this application, such as Figure 7As shown, the N-order longitudinal coupling filter can be a 5th-order longitudinal coupling filter, and the N coupling units can include three first coupling units 311 and two second coupling units 312. Correspondingly, the first gap L1 includes first sub-gap corresponding to each of the three first coupling units 311, and the second gap L2 includes second sub-gap corresponding to each of the two second coupling units 312. The isolation unit 400 is electrically connected to at least one of the first and second sub-gap, eliminating the need for additional space for the isolation unit 400, which is beneficial for the miniaturization of the elastic wave filter. It should be noted that the N-order longitudinal coupling filter can be a 5th-order longitudinal coupling filter, and the N coupling units can also include two first coupling units 311 and three second coupling units 312, depending on the specific situation.
[0072] Based on the above, in one embodiment of this application, such as Figure 7 As shown, the isolation unit 400 may include j first isolation units 401, 1≤j≤3. The first isolation unit 401 is electrically connected to the first sub-gap. That is, the isolation unit 400 may include the first isolation unit 401 disposed in the first sub-gap. At this time, the first isolation unit 401 is electrically connected between the input terminal 1 and the second ground terminal 4 of the Nth order longitudinal coupling filter 300, and the first isolation unit 401 may be disposed in at least one of the three first sub-gap.
[0073] In another embodiment of this application, such as Figure 8 As shown, the isolation unit 400 may include k second isolation units 402, 1≤k≤2. The second isolation units 402 are electrically connected to the second sub-gap. That is, the isolation unit 400 may include the second isolation units 402 disposed in the second sub-gap. At this time, the second isolation units 402 are electrically connected between the output terminal 2 of the Nth order longitudinal coupling filter 300 and the first ground terminal 3, and the second isolation unit 402 may be disposed in at least one of the two second sub-gap.
[0074] In yet another embodiment of this application, as Figure 9 As shown, the isolation unit 400 may include j first isolation units 401 and k second isolation units 402, where 1≤j≤3 and 1≤k≤2. The first isolation units 401 are electrically connected to the first sub-gap, and the second isolation units 402 are electrically connected to the second sub-gap.
[0075] As described above, the isolation unit 400 can be positioned between the input terminal 1 and the second ground terminal 4 of the N-order longitudinal coupling filter 300, or between the output terminal 2 and the first ground terminal 3 of the N-order longitudinal coupling filter 300. Alternatively, the isolation unit 400 can be positioned between both the input terminal 1 and the second ground terminal 4 of the N-order longitudinal coupling filter 300 and between the output terminal 2 and the first ground terminal 3 of the N-order longitudinal coupling filter 300. In other words, the position and number of the isolation units 400 can be flexibly arranged, allowing for customization based on actual needs to suit a wider range of applications. Furthermore, when the elastic wave filter has high capacitance requirements for the isolation units 400, this can be achieved by increasing the number of isolation units 400, thus meeting the needs of even more application scenarios.
[0076] Based on the elastic wave filter described in any of the above embodiments, this application also provides a radio frequency module, which includes the elastic wave filter described in any of the above embodiments.
[0077] Based on the above-described radio frequency module, this application also provides an electronic device that includes the above-described radio frequency module.
[0078] In summary, this application provides an elastic wave filter, a radio frequency module, and an electronic device. The elastic wave filter includes: a substrate, a plurality of series resonators and a plurality of parallel resonators located on the substrate, an N-order longitudinal coupling filter connected in series between the plurality of series resonators, and an isolation unit. The input terminal of the N-order longitudinal coupling filter is electrically connected to the second terminal of the series resonator in front of it, and the output terminal of the N-order longitudinal coupling filter is electrically connected to the first terminal of the series resonator behind it. The isolation unit is electrically connected to at least one of a first gap and a second gap. The first gap is the gap between the input terminal of the N-order longitudinal coupling filter and a second ground terminal along a first direction, and the second gap is the gap between the output terminal of the N-order longitudinal coupling filter and a first ground terminal along the first direction. The resonant frequency of the isolation unit is located outside the passband of the elastic wave filter and within the isolation band of the elastic wave filter. Therefore, the elastic wave filter has an isolation unit that can suppress its isolation frequency band. Moreover, the isolation unit does not require additional chip area for setting up at least one of the first gap and the second gap, which is beneficial to the miniaturization of the elastic wave filter and does not impair the out-of-band suppression of the elastic wave filter. Consequently, the elastic wave filter can be smaller in size and have higher out-of-band suppression.
[0079] The various embodiments in this specification are described in a progressive, parallel, or combined manner. Each embodiment focuses on its differences from other embodiments, and similar or identical areas between embodiments can be referred to interchangeably. For the apparatuses disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant details can be found in the description of the method area.
[0080] It should be noted that, in the description of this application, the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component centrally located at the same time.
[0081] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.
[0082] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An elastic wave filter characterized by, The elastic wave filter comprises: a substrate; a plurality of resonators on the substrate, the plurality of resonators comprising a plurality of series resonators and a plurality of parallel resonators; the plurality of series resonators are arranged in series in a first path, and the plurality of parallel resonators are arranged in a second path; at least one of the first end and the second end of the series resonator is grounded through the parallel resonator; the first end of the series resonator is electrically connected to the input end of the elastic wave filter, and the second end is electrically connected to the output end of the elastic wave filter; an N-order longitudinal coupling filter, N being an odd number not less than 3; the N-order longitudinal coupling filter is arranged in the first path and along a first direction; the input end of the N-order longitudinal coupling filter is electrically connected to the second end of the series resonator in front, and the output end is electrically connected to the first end of the series resonator behind; the first direction is parallel to the plane in which the substrate is located, and along the first path, the input end of the N-order longitudinal coupling filter points to the output end from the input end of the elastic wave filter; the input end of the N-order longitudinal coupling filter is grounded through the first grounding end on the side of the output end, and the output end is grounded through the second grounding end on the side of the input end; an isolation unit electrically connected to at least one of a first gap and a second gap; the first gap is a gap between the input end of the N-order longitudinal coupling filter and the second grounding end along the first direction; the second gap is a gap between the output end of the N-order longitudinal coupling filter and the first grounding end along the first direction; wherein the resonant frequency of the isolation unit is located outside the passband frequency range of the elastic wave filter and inside the isolation frequency range of the elastic wave filter.
2. The elastic wave filter according to claim 1, wherein: the isolation unit is an interdigital capacitor; or the isolation unit is a resonator.
3. The elastic wave filter according to claim 1, characterized by, The plurality of series resonators comprises a first series resonator and a second series resonator, and the plurality of parallel resonators comprises a first parallel resonator and a second parallel resonator; the first series resonator is closer to the input end of the elastic wave filter than the second series resonator; the first parallel resonator is electrically connected between the first end of the first series resonator and the input end of the elastic wave filter; and the second parallel resonator is electrically connected between the second end of the second series resonator and the output end of the elastic wave filter; the N-order longitudinal coupling filter is located between the first series resonator and the second series resonator; the input end of the N-order longitudinal coupling filter is electrically connected to the second end of the first series resonator, and the output end is electrically connected to the first end of the second series resonator.
4. The elastic wave filter according to claim 1, wherein: the N-order longitudinal coupling filter comprises N coupling units arranged along a second direction; the N coupling units comprise m first coupling units and n second coupling units, m≥1, n≥1, and m+n=N; the second direction is parallel to the plane in which the substrate is located, and the second direction is perpendicular to the first direction. The first coupling units and the second coupling units are arranged alternately along the second direction, and along the first direction, one end of the first coupling unit close to the front series resonator is electrically connected to the input end of the N-stage longitudinal coupled filter, and one end of the first coupling unit close to the rear series resonator is electrically connected to the first ground end, one end of the second coupling unit close to the rear series resonator is electrically connected to the output end of the N-stage longitudinal coupled filter, and one end of the second coupling unit close to the front series resonator is electrically connected to the second ground end; The first gap is a gap between the input end of the N-stage longitudinal coupled filter and the second ground end corresponding to the second coupling unit along the first direction, and the second gap is a gap between the output end of the N-stage longitudinal coupled filter and the first ground end corresponding to the first coupling unit along the first direction.
5. The elastic wave filter of claim 4, wherein N = 3, and the N-stage longitudinal coupled filter is a 3-stage longitudinal coupled filter; or N = 5, and the N-stage longitudinal coupled filter is a 5-stage longitudinal coupled filter; or N = 7, and the N-stage longitudinal coupled filter is a 7-stage longitudinal coupled filter; or N = 9, and the N-stage longitudinal coupled filter is a 9-stage longitudinal coupled filter.
6. The elastic wave filter of claim 5, wherein the N-stage longitudinal coupled filter is a 5-stage longitudinal coupled filter, and the N coupling units include 3 first coupling units and 2 second coupling units; the first gap includes a first sub-gap corresponding to each of the 3 first coupling units, the second gap includes a second sub-gap corresponding to each of the 2 second coupling units, and the isolation unit is electrically connected to at least one of the first sub-gap and the second sub-gap.
7. The elastic wave filter of claim 6, wherein the isolation unit includes j first isolation units, 1 ≤ j ≤ 3, and the first isolation units are electrically connected to the first sub-gap; or the isolation unit includes k second isolation units, 1 ≤ k ≤ 2, and the second isolation units are electrically connected to the second sub-gap.
8. The elastic wave filter of claim 6, wherein the isolation unit includes j first isolation units and k second isolation units, 1 ≤ j ≤ 3, 1 ≤ k ≤ 2; the first isolation units are electrically connected to the first sub-gap, and the second isolation units are electrically connected to the second sub-gap.
9. A radio frequency module, characterized by An elastic wave filter according to any one of claims 1-8.
10. An electronic device, comprising: A radio frequency module according to claim 9.