Filter and multiplexer
By setting the first element in the filter in parallel with the acoustic resonant network, and compensating the passband bandwidth by the compensation element, the problem of signal interference and insertion loss is solved, and more efficient filtering performance and passband stability are achieved.
Patent Information
- Application Number
- CN202411689044.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-03-14
AI Technical Summary
In communication systems, signal interference leads to a reduced signal transmission efficiency, and existing filters have shortcomings in suppressing out-of-band signal interference and reducing insertion loss.
A filter including an acoustic resonant network, a compensation element and a first element is designed, and the passband bandwidth is compensated by providing the first element with a series resonator and/or a parallel resonator in the acoustic resonant network.
It effectively reduces the insertion loss of the filter, improves the roll-off characteristics and filtering performance, and ensures the stability of the passband bandwidth.
Smart Images
Figure CN119628589A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of signal processing, and in particular to a filter and a multiplexer. Background Art
[0002] In communication systems, signal interference can significantly reduce signal transmission efficiency. Filters can effectively suppress out-of-band signal interference. In modern communications, there is an increasing demand for filters to suppress out-of-band signal interference, improve out-of-band suppression capabilities, and reduce insertion loss in the filter passband. Summary of the invention
[0003] The present invention provides a filter and a multiplexer to improve the roll-off characteristics of the filter and ensure the bandwidth of the passband, reduce the transition bandwidth and the passband insertion loss, and improve the filtering performance of the filter.
[0004] According to one aspect of the present invention, there is provided a filter, comprising a first port, a second port, a third port and at least one filtering unit; The filtering unit comprises an acoustic resonance network, a compensation element and at least one first element; The acoustic resonance network includes a series resonator and a parallel resonator; the series resonator is connected between the first port and the second port, one end of the parallel resonator is connected to the series resonator, and the other end of the parallel resonator is connected to the third port; The first element is connected in series with the compensation element and then connected in parallel with the series resonator, and / or the first element is connected in series with the compensation element and then connected in parallel with the parallel resonator.
[0005] Optionally, the compensation element includes an inductive element, and the first element is connected in series with the inductive element and then connected in parallel with the series resonator, and / or the first element is connected in series with the inductive element and then connected in parallel with the parallel resonator.
[0006] Optionally, the first element includes a capacitive element, which is connected in series with the compensation element and then connected in parallel with the resonator; wherein the resonator includes at least one of the series resonator and the parallel resonator.
[0007] Optionally, the acoustic resonance network includes a first series resonator, a second series resonator and a first parallel resonator, and the filtering unit includes three first elements, the first end of the first series resonator is connected to the first port, the second end of the first series resonator, the first end of the first parallel resonator and the first end of the compensation element are connected to the first end of the second series resonator, the second end of the second series resonator is connected to the second port, and the second end of the first parallel resonator is connected to the third port; the first end of each of the first elements is respectively connected to the first end of the first series resonator, the second end of the second series resonator and the second end of the first parallel resonator, and the second end of each of the first elements is connected to the second end of the compensation element.
[0008] Optionally, an LC filter unit is further included, and the LC filter unit is connected in series between the first port and the second port.
[0009] Optionally, the filter includes at least two filtering units, and at least two filtering units are connected in series between the first port and the second port.
[0010] Optionally, a fourth port is further included, and the fourth port is arranged between the filtering units.
[0011] Optionally, the acoustic resonance network also includes a second parallel resonator and a third parallel resonator; the first end of the second parallel resonator is connected to the first end of the first series resonator, the second end of the second parallel resonator is connected to the third port, the first end of the third parallel resonator is connected to the second end of the second series resonator, and the second end of the third parallel resonator is connected to the third port.
[0012] According to another aspect of the present invention, there is provided a multiplexer comprising the filter described in any one of the first aspects.
[0013] The technical solution provided by the embodiment of the present invention reduces the equivalent impedance value of the branch where the series resonator and / or the parallel resonator are located by setting a first element in parallel with the series resonator and / or the parallel resonator in the acoustic resonance network, while reducing the overall electromechanical coupling coefficient of the resonator and increasing the Q value, thereby reducing the insertion loss of the filter, improving the roll-off characteristics of the filter, and further improving the filtering performance of the filter; by setting a compensation element in series with the first element and then connecting it in parallel with the series resonator and / or the parallel resonator, the passband bandwidth of the filter is compensated, thereby improving the filtering performance of the filter as a whole.
[0014] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0016] Figure 1 A schematic diagram of the structure of a filter provided by an embodiment of the present invention; Figure 2 A schematic diagram of the structure of another filter provided by an embodiment of the present invention; Figure 3 A schematic diagram of the structure of another filter provided by an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a filter provided by the prior art; Figure 5 A schematic diagram for comparing the performance of different filters provided by an embodiment of the present invention; Figure 6 for Figure 5 A partial enlarged schematic diagram of the passband portion in the provided performance comparison schematic diagram; Figure 7 for Figure 5 A partial enlarged schematic diagram of the adjacent band portion in the provided performance comparison schematic diagram; Figure 8 A schematic diagram of the structure of another filter provided by an embodiment of the present invention; Fig. 9 A schematic diagram of the structure of another filter provided by an embodiment of the present invention; Fig.10 A schematic diagram of the structure of another filter provided by an embodiment of the present invention; Fig.11 A schematic diagram of the structure of another filter provided by an embodiment of the present invention; Fig.12 A schematic diagram of the structure of a multiplexer provided in an embodiment of the present invention. DETAILED DESCRIPTION
[0017] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.
[0018] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0019] Figure 1 A schematic diagram of the structure of a filter provided by an embodiment of the present invention. Figure 1 As shown, the filter comprises a first port A, a second port B, a third port C and at least one filtering unit 10; the filtering unit 10 comprises an acoustic resonance network 100, a compensation element 200 and at least one first element 300; the acoustic resonance network 100 comprises a series resonator 110 and a parallel resonator 120; the series resonator 110 is connected between the first port A and the second port B, one end of the parallel resonator 120 is connected to the series resonator 110, and the other end of the parallel resonator 120 is connected to the third port C; the first element 300 is connected in series with the compensation element 200 and then connected in parallel with the series resonator 110, and / or the first element 300 is connected in series with the compensation element 200 and then connected in parallel with the parallel resonator 120.
[0020] Specifically, the series resonator 110 is connected in series between the first port A and the second port B. At this time, the first port A and the second port B can be respectively used as two ports of the acoustic resonance network 100. At the same time, one end of the parallel resonator 120 is connected to the series resonator 110, and one end of the parallel resonator 120 connected to the third port C can be used as another port of the acoustic resonance network 100. Exemplarily, Figure 1It is shown that the acoustic resonance network 100 includes two series resonators 110 and a parallel resonator 120. One end of the parallel resonator 120 is connected to the node O between the two series resonators 110, and the other end is connected to the third port C. The first port A, the second port B and the third port C can be connected to the elements of the external circuit respectively, so that the filter can be connected to different types of external circuits, thereby increasing the application range of the filter. The series resonator 110 and the parallel resonator 120 can be acoustic wave resonators. Exemplarily, the resonator 12 can be at least one of a bulk acoustic wave (BAW) resonator, a surface acoustic wave (SAW) resonator and a film bulk acoustic resonator (FBAR) filter. The present embodiment does not specifically limit the number of the first element 300, and the first element 300 can be connected in parallel with any number of series resonators 110 or parallel resonators 120 in the acoustic resonance network 100. Exemplarily, Figure 1 It is shown that the second end of the compensation element 200 is connected in series with the three first elements 300 respectively, and then connected in parallel with the branches of the two series resonators 110 and the parallel resonator 120 respectively. The first end of the compensation element 200 is connected to the node O between the two series resonators 110, and the second end of the compensation element 200 is connected in series with the first element 300 and then connected in parallel with the series resonator 110 and / or the parallel resonator 120. After the first element 300 is connected in parallel with the series resonator 110 or the parallel resonator 120, the equivalent impedance value of the branch where the series resonator 110 or the parallel resonator 120 is located is reduced, and the loss of the branch where the resonator is located can be reduced, the insertion loss of the filter is reduced, and the quality factor Q of the filter is improved, thereby improving the roll-off characteristics of the filter and the filtering performance of the filter. When the quality factor of the first element 300 itself is less than the quality factor of the series resonator 110 or the parallel resonator 120, the compensation element 200 is connected in series with the first element 300 and then connected in parallel with the series resonator 110 or the parallel resonator 120, which can compensate for the degree of decrease in the electromechanical coupling coefficient Kp of the resonator caused by the first element 300, so as to ensure the passband bandwidth of the filter. The electromechanical coupling coefficient Kp of the resonator represents the conversion capability between the mechanical energy and the electrical energy of the resonator, and can also be numerically represented as the relative bandwidth between the resonator resonance point and the anti-resonance point. Generally, the larger the coupling coefficient Kp of the resonator, the larger the relative bandwidth of the filter. Therefore, by setting the compensation element 200 to be connected in series with the first element 300 and then connected in parallel with the series resonator 110 or the parallel resonator 120, the electromechanical coupling coefficient Kp can be improved, so that the passband bandwidth of the filter can be guaranteed on the basis of improving the roll-off characteristics and the quality factor of the filter, thereby improving the filtering performance of the filter.
[0021] The technical solution provided by the embodiment of the present invention reduces the equivalent impedance value of the branch where the series resonator and / or the parallel resonator are located by setting a first element in parallel with the series resonator and / or the parallel resonator in the acoustic resonance network, thereby reducing the insertion loss of the filter, improving the roll-off characteristics of the filter, and further improving the filtering performance of the filter; by setting a compensation element in series with the first element and then connecting it in parallel with the series resonator and the parallel resonator, the passband bandwidth of the filter is guaranteed, thereby improving the filtering performance of the filter as a whole.
[0022] Optionally, Figure 2 A schematic diagram of the structure of another filter provided by an embodiment of the present invention. Figure 2 The compensation element 200 includes an inductive element L, the first element 300 is connected in series with the inductive element L and then connected in parallel with the series resonator 110 , and / or the first element 300 is connected in series with the inductive element L and then connected in parallel with the parallel resonator 120 .
[0023] Specifically, the inductive element L may be an inductor. After being connected in series with the first element 300, the inductor L is connected in parallel with the series resonator 110 and the parallel resonator 120, which can compensate for the decrease in the electromechanical coupling coefficient Kp of the resonator caused by the first element 300, and improve the electromechanical coupling coefficient Kp of the branch where the series resonator 110 and the parallel resonator 120 are located, thereby ensuring the passband bandwidth of the filter and improving the filtering performance of the filter on the basis of improving the roll-off characteristics and quality factor of the filter.
[0024] Optionally, Figure 3 A schematic diagram of the structure of another filter provided by an embodiment of the present invention. Figure 3 The first element 300 includes a capacitive element C, which is connected in series with the compensation element 200 and then connected in parallel with the resonator; wherein the resonator includes at least one of a series resonator 110 and a parallel resonator 120 .
[0025] Specifically, the first element 300 may be a capacitor C. For example, Figure 3As shown, the three first elements are set as three capacitors C, which are connected in parallel with the series resonator 110 and the parallel resonator 120 respectively. The first element 300 can be used to reduce the equivalent impedance of the branch where the series resonator 110 and the parallel resonator 120 are located, so as to reduce the loss of the branch where the resonator is located, reduce the insertion loss of the filter, and improve the roll-off characteristics of the filter. Moreover, the series resonator 110 and the parallel resonator 120 can be equivalent to the Modified butterworth-van dyke (MBVD) model, that is, a circuit structure composed of a series LC circuit and a capacitor in parallel. The first element 300 is set to be connected in parallel with the capacitor C to avoid the first element 300 affecting the resonant characteristics of the resonator, so that the filter can reduce the insertion loss of the filter, improve the roll-off characteristics of the filter, and improve the filtering performance of the filter without affecting the resonant characteristics of the resonator.
[0026] Optionally, based on the above embodiment, continue to refer to Figure 3 The acoustic resonance network 100 includes a first series resonator 1101, a second series resonator 1102 and a first parallel resonator 1201, and the filtering unit 10 includes three first elements, a first end of the first series resonator 1101 is connected to the first port A, a second end of the first series resonator 1101, a first end of the first parallel resonator 1201 and a first end of the compensation element L are connected to the first end of the second series resonator 1102, a second end of the second series resonator 1102 is connected to the second port B, and a second end of the first parallel resonator 1201 is connected to the third port C; a first end of the first element 300 is respectively connected to the first end of the first series resonator 1101, the second end of the second series resonator 1102 and the second end of the first parallel resonator 1201, and a second end of each first element 300 is connected to the second end of the compensation element L.
[0027] Specifically, the acoustic resonance network 100 may be a "T" type network consisting of a first series resonator 1101, a second series resonator 1102, and a first parallel resonator 1201. The three first elements may be capacitor C1, capacitor C2, and capacitor C3. Capacitor C1 is connected in series with the inductor L and then connected in parallel with the first series resonator 1101, capacitor C2 is connected in series with the inductor L and then connected in parallel with the second series resonator 1102, and capacitor C3 is connected in series with the inductor L and then connected in parallel with the third series resonator 1103.
[0028] For example, Figure 4 A schematic diagram of a filter structure provided by the prior art, the specific structure of which is similar to Figure 3 The “T” type resonant network 100 is the same as in FIG. Figure 5A performance comparison diagram of different filters provided by an embodiment of the present invention, wherein the horizontal axis is frequency and the vertical axis is insertion loss. Figure 6 for Figure 5 The partial enlarged schematic diagram of the passband part in the performance comparison diagram provided, Figure 7 for Figure 5 The performance comparison diagram provided is a partial enlarged diagram of the adjacent band part. Curve L1 is Figure 3 The frequency-insertion loss curve of the filter provided in the embodiment, curve L2 is Figure 4 The frequency-insertion loss curve of the filter provided by the prior art is shown in FIG. Figure 6 and Figure 7 As shown, the insertion loss of curve L1 in the passband is about -0.2dB, while the insertion loss of curve L2 in the passband is about -0.3dB. Compared with the filter structure of the prior art, Figure 3 The filter structure provided in the embodiment reduces the insertion loss in the passband by 0.1 dB. Moreover, when the center frequency of the filter is 5.1 GHz, the frequency corresponding to the first notch point M1 of the curve L1 in the adjacent band is 5.24 GHz, and the frequency corresponding to the first notch point M2 of the curve L2 in the adjacent band is 5.315 GHz. Compared with the filter structure of the prior art, Figure 3 The filter structure provided in the embodiment reduces the transition bandwidth by about 75MHz and improves the roll-off characteristics of the filter. Figure 4 The filter structure provided in the embodiment can reduce the transition bandwidth of the filter, significantly improve the adjacent band suppression capability and roll-off characteristics of the filter, and reduce the insertion loss of the filter passband, thereby improving the filtering performance of the filter.
[0029] Optionally, Figure 8 A schematic diagram of the structure of another filter provided by an embodiment of the present invention. Figure 8 The filter further includes an LC filter unit 20 , which is connected in series between the first port A and the second port B.
[0030] Specifically, the LC filter unit 20 can adjust the passband of the filter so that the filter has a wider passband. When the filter includes both the LC filter unit 20 and the filter unit 10, it can ensure that the filter has a wider passband, and at the same time improve the roll-off slope of the filter's adjacent band, thereby improving the filter's adjacent band suppression capability and thus improving the filter's filtering performance. For example, Fig.10 As shown, the filter includes two filter units 10 , the two filter units 10 are connected in series between the first port A and the second port B, and the LC filter unit 20 is connected in series between the two filter units 10 .
[0031] It should be noted that, in other embodiments, the LC filter unit 20 may also be disposed between the first port A and the first filter unit 10 , or between the second filter unit 10 and the second port B, which is not limited here.
[0032] Optionally, Fig. 9 A schematic diagram of the structure of another filter provided by an embodiment of the present invention. Fig. 9 The filter comprises at least two filter units 10 , and the at least two filter units 10 are connected in series between the first port A and the second port B.
[0033] Specifically, when at least two filter units 10 are connected in series between the first port A and the second port B, different filter units 10 can respectively reduce the bandwidth of the adjacent band within the adjacent band of the filter, thereby further improving the roll-off slope of the adjacent band, further improving the adjacent band suppression capability of the filter, and thus improving the filtering performance of the filter. It should be noted that, in other embodiments, the filter may include multiple filter units 10, each of which may be connected in series between the first port A and the second port B, which is not limited here.
[0034] Optionally, Fig.10 A schematic diagram of the structure of another filter provided by an embodiment of the present invention. Fig.10 The filter further includes a fourth port D, which is disposed between the filter units 10 .
[0035] Specifically, Fig.10 exemplarily shows that the filter includes two filter units 10, and a fourth port D is provided between the two filter units 10. The fourth port D can be used to connect to components of an external circuit, so that the filter can be connected to different types of external circuits, further increasing the application range of the filter.
[0036] Optionally, Fig.11 A schematic diagram of the structure of another filter provided by an embodiment of the present invention. Fig.11 The parallel resonator 120 also includes a second parallel resonator 1202 and a third parallel resonator 1203; one end of the second parallel resonator 1202 is connected to the first series resonator 1101, the other end of the second parallel resonator 1202 is connected to the first parallel resonator 1201, one end of the third parallel resonator 1203 is connected to the second series resonator 1102, and the other end of the third parallel resonator 1203 is connected to the first parallel resonator 1201.
[0037] Specifically, the parallel resonator 120 may also include a plurality of parallel resonators. Fig.11As shown, the parallel resonator 120 also includes a second parallel resonator 1202 and a third parallel resonator 1203. The second parallel resonator 1202 and the third parallel resonator 1203. The capacitor C can be connected in series with the inductor L and then connected in parallel with any parallel resonator, thereby reducing the equivalent impedance value of the branch where the parallel resonator is located, thereby reducing the insertion loss of the filter, improving the roll-off characteristics of the filter, and further improving the filtering performance of the filter.
[0038] An embodiment of the present invention further provides a multiplexer. Fig.12 A schematic diagram of the structure of a multiplexer provided by an embodiment of the present invention. Fig.12 As shown, the multiplexer includes the filter provided by any embodiment of the present invention.
[0039] Specifically, the multiplexer includes a first terminal IN and at least two second terminals; each filter is connected in series between the first terminal IN and any second terminal of the multiplexer. Specifically, the multiplexer includes a first terminal IN and n second terminals, which are OUT1, OUT2...OUTn. Each filter is connected in series between the first terminal IN and a second terminal. For example, the first filter is connected in series between the first terminal IN and the first second terminal OUT1, the second filter is connected in series between the first terminal IN and the first second terminal OUT2...and so on. Since the multiplexer has the filter provided by any embodiment of the present invention, it has the same beneficial effects as the filter, which will not be repeated here.
[0040] It should be noted that the multiplexer may also include other filters, which are connected in series between the first end IN and any second end. The other filters may be low-pass filters, high-pass filters or band-pass filters, which are not limited in the embodiment of the present invention.
[0041] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.
[0042] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A filter, characterized in that: comprising a first port, a second port, a third port and at least one filtering unit; The filtering unit comprises an acoustic resonance network, a compensation element and at least one first element; The acoustic resonance network includes a series resonator and a parallel resonator; the series resonator is connected between the first port and the second port, one end of the parallel resonator is connected to the series resonator, and the other end of the parallel resonator is connected to the third port; The first element is connected in series with the compensation element and then connected in parallel with the series resonator, and / or the first element is connected in series with the compensation element and then connected in parallel with the parallel resonator.
2. The filter according to claim 1, characterized in that The compensation element includes an inductive element, and the first element is connected in series with the inductive element and then connected in parallel with the series resonator, and / or the first element is connected in series with the inductive element and then connected in parallel with the parallel resonator.
3. The filter according to claim 1, characterized in that The first element includes a capacitive element, which is connected in series with the compensation element and then connected in parallel with the resonator; wherein the resonator includes at least one of the series resonator and the parallel resonator.
4. The filter according to any one of claims 1 to 3, characterized in that: The acoustic resonance network includes a first series resonator, a second series resonator and a first parallel resonator, and the filtering unit includes three first elements, the first end of the first series resonator is connected to the first port, the second end of the first series resonator, the first end of the first parallel resonator and the first end of the compensation element are connected to the first end of the second series resonator, the second end of the second series resonator is connected to the second port, and the second end of the first parallel resonator is connected to the third port; the first end of each of the first elements is respectively connected to the first end of the first series resonator, the second end of the second series resonator and the second end of the first parallel resonator, and the second end of each of the first elements is connected to the second end of the compensation element.
5. The filter according to claim 1, characterized in that The device also includes an LC filter unit connected in series between the first port and the second port.
6. The filter according to claim 1, characterized in that The filter includes at least two filter units, and the at least two filter units are connected in series between the first port and the second port.
7. The filter according to claim 6, characterized in that It also includes a fourth port, which is arranged between the filter units.
8. The filter according to claim 4, characterized in that The acoustic resonance network also includes a second parallel resonator and a third parallel resonator; the first end of the second parallel resonator is connected to the first end of the first series resonator, the second end of the second parallel resonator is connected to the third port, the first end of the third parallel resonator is connected to the second end of the second series resonator, and the second end of the third parallel resonator is connected to the third port.
9. A multiplexer, characterized in that: A filter comprising the filter described in any one of claims 1 to 8.