Filter and communication equipment comprising same

Abstract

The utility model relates to a filter and communication equipment. The filter comprises an input terminal, an output terminal, a filter network, a first matching unit and a second matching unit, the filter network is arranged between the input terminal and the output terminal and comprises M series branches and N parallel branches, wherein M and N are natural numbers; the first matching unit is arranged between the input terminal and the filter network, and the second matching unit is arranged between the filter network and the output terminal; each series branch comprises a resonance unit, one end of the parallel branch is connected to a node between the series branches, and the other end of the parallel branch is grounded; each parallel branch, the first matching unit and the second matching unit at least comprise an inductor; when any three or more inductors in the filter are coupled, the current flow directions of the coupled inductors on the printed circuit board of the filter cannot be set in the same direction.

Description

Technical Field

[0001] The utility model relates to a filter, and more particularly to a radio frequency filter and a communication device comprising the radio frequency filter. Background Art

[0002] Portable communication devices, such as mobile phones, laptops, and personal digital assistants, need to acquire and transmit signals. Different signals require different communication methods and frequency ranges. For example, cellular, Wi-Fi, and GPS-based communication methods are used to acquire and transmit different signals. To meet the signal acquisition and transmission needs of portable communication devices, RF filters have emerged. With the increasing commercialization of 5G, the demand for RF filters is also increasing.

[0003] See also Figure 1 , Figure 1 The following is a block diagram of the architecture of a conventional radio frequency filter, which includes an input terminal IN, an output terminal OUT, and a filter network. The filter network is connected between the input terminal IN and the output terminal OUT and includes a series branch and a parallel branch. The boxes in the series and parallel branches represent resonant units. The resonant units can be composed of LC lumped elements or acoustic wave resonators. They can also be composed of different types of devices, such as a resonant unit composed of an LC lumped element and a surface acoustic wave resonator (SMR), or a resonant unit composed of an SMR acoustic wave resonator and a film bulk acoustic resonator (FBAR).

[0004] In the prior art, RF filters typically use winding on a printed circuit board (PCB) to form inductors in each parallel branch. The winding inductors on the PCB achieve different out-of-band suppression requirements. However, their relatively small Q value affects overall performance, especially out-of-band suppression. Utility Model Content

[0005] In response to the above technical problems, the utility model has carefully designed a radio frequency filter, avoiding the above technical problems of existing filters, and successfully developed a high-performance radio frequency filter that can use coupling to enhance the suppression of special frequency bands while ensuring the suppression of high frequency bands.

[0006] The following is a brief overview of the present invention to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important aspects of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is simply to present certain concepts in a simplified form as a prelude to the more detailed description discussed later.

[0007] According to one aspect of the present invention, a filter is provided, comprising: an input terminal, an output terminal, a filter network, a first matching unit, and a second matching unit; the filter network is arranged between the input terminal and the output terminal and comprises M series branches and N parallel branches, where M and N are natural numbers; the first matching unit is arranged between the input terminal and the filter network, and the second matching unit is arranged between the filter network and the output terminal; each series branch comprises a resonant unit, one end of the parallel branch is connected to a node between the series branches, and the other end of the parallel branch is grounded; each parallel branch, the first matching unit, and the second matching unit comprises at least one inductor; when any three or more inductors in the filter are coupled, the current flows of the coupled inductors on the filter printed circuit board cannot all be arranged in the same direction.

[0008] Furthermore, the mutual coupling is regulated by adjusting the distance between the coupled inductor whose current flow direction on the filter printed circuit board is different from that of the other inductors.

[0009] Furthermore, different couplings are achieved by adjusting the number of metal layers on the filter printed circuit board of the inductors with the same current flow direction in the coupled inductors.

[0010] Furthermore, the coupling is adjusted by sharing a ground with the filter chip with one of the coupled inductors having the same current flow direction.

[0011] Furthermore, the filtering network constitutes a T-type filtering network, including 5 series branches and 5 parallel branches, each series branch and each parallel branch has a resonance unit, and the resonance unit is selected from: a resonance unit composed of LC lumped elements, a resonance unit composed of surface acoustic wave resonators, a resonance unit composed of bulk acoustic wave resonators, a resonance unit composed of LC lumped elements and surface acoustic wave resonators, a resonance unit composed of LC lumped elements and bulk acoustic wave resonators, and at least one of a resonance unit composed of surface acoustic wave resonators and bulk acoustic wave resonators.

[0012] Furthermore, the first end of the inductor L1 on the first parallel branch is connected to the resonant unit on the first parallel branch, and the second end of the inductor L1 is grounded; the first end of the inductor L2 on the second parallel branch is connected to the resonant unit on the second parallel branch, and the second end of the inductor L2 is grounded; the first end of the inductor L3 on the third parallel branch is connected to the resonant unit on the third parallel branch, and the second end of the inductor L3 is grounded; the first end of the inductor L4 on the fourth parallel branch is connected to the resonant unit on the fourth parallel branch, and the second end of the inductor L4 is grounded; the first end of the inductor L5 on the fifth parallel branch is connected to the resonant unit on the fifth parallel branch, and the second end of the inductor L5 is grounded.

[0013] Furthermore, the first matching unit includes a first matching inductor, and the second matching unit includes a second matching inductor and a third matching inductor, wherein the first end of the first matching inductor is connected to the input terminal, and the second end of the first matching inductor is grounded; the first end of the second matching inductor is connected to the output end of the filter network, and the second end of the second matching inductor is connected to the output terminal; the first end of the third matching inductor is connected to the output terminal, and the second end of the third matching inductor is grounded.

[0014] Furthermore, when there is coupling between the inductor L3, the inductor L5 and the third matching inductor, the current flow direction of the inductor L3 and the inductor L5 on the filter printed circuit board is set to a first flow direction, and the current flow direction of the third matching inductor on the filter printed circuit board is set to a second flow direction opposite to the first flow direction; or the current flow direction of the inductor L3 and the second matching inductor on the filter printed circuit board is set to the second flow direction, and the current flow direction of the inductor L5 on the filter printed circuit board is set to the first flow direction opposite to the second flow direction.

[0015] Furthermore, when coupling exists between the inductor L3, the inductor L5, the second matching inductor, and the third matching inductor, the current flow direction of the inductor L3 and the inductor L5 on the filter printed circuit board is set to a first flow direction, and the current flow direction of the second matching inductor and the third matching inductor on the filter printed circuit board is set to a second flow direction opposite to the first flow direction.

[0016] According to another aspect of the present invention, a communication device is provided, comprising any one of the above filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The following description of the present invention will provide a more comprehensive understanding of the above and other purposes, features, and advantages of the present invention, with reference to the accompanying drawings. The accompanying drawings are intended only to illustrate the principles of the present invention. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale.

[0018] Figure 1 The following is a block diagram showing the architecture of a radio frequency filter in the prior art;

[0019] Figure 2 Showing a structural block diagram of the filter provided by the utility model;

[0020] Figure 3 A schematic diagram showing the current flow between coupled inductors in one embodiment of the filter provided by the present invention;

[0021] Figure 4 A schematic diagram showing the current flow between coupled inductors in another embodiment of the filter provided by the present invention;

[0022] Figure 5 A schematic diagram showing the current flow between coupled inductors in another embodiment of the filter provided by the present invention. DETAILED DESCRIPTION

[0023] The following describes exemplary embodiments of the present invention in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features that implement the present invention are described in this specification. However, it should be understood that in developing any such implementation of the present invention, many decisions specific to the invention may be made to achieve the developer's specific goals, and these decisions may vary from one invention to another.

[0024] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, the accompanying drawings only show device structures closely related to the solutions according to the present invention, while other details that are not closely related to the present invention are omitted.

[0025] It should be understood that the present invention is not limited to the described embodiments due to the following description with reference to the accompanying drawings. In the present invention, features between different embodiments may be replaced or borrowed, and one or more features may be omitted in one embodiment, where feasible.

[0026] See also Figure 2 , Figure 2The structure block diagram of the filter provided by the present invention is shown. The filter includes an input terminal IN, an output terminal OUT, and a filter network 100. The filter network 100 is connected between the input terminal IN and the output terminal OUT. The filter network 100 includes a series branch and a parallel branch, wherein the boxes on the series branch and the parallel branch represent resonant units. The resonant unit can be a resonant unit composed of LC lumped elements; a resonant unit composed of one or more surface acoustic wave resonators; a resonant unit composed of one or more bulk acoustic wave resonators; or a resonant unit composed of different types of devices, such as a resonant unit composed of an LC lumped element and a surface acoustic wave resonator, a resonant unit composed of an LC lumped element and an FBAR resonator, or a resonant unit composed of an SMR acoustic wave resonator and an FBAR acoustic wave resonator. Each parallel branch of the filter can include an inductor connected to ground.

[0027] A filter network 100 provided in this embodiment has at least M series branches and N parallel branches, where M and N are natural numbers. Figure 2 The filter network 100 schematically includes five series branches and five parallel branches. The first parallel branch includes an inductor L1, the second parallel branch includes an inductor L2, the third parallel branch includes an inductor L3, the fourth parallel branch includes an inductor L4, and the fifth parallel branch includes an inductor L5.

[0028] The first end of inductor L1 in the first parallel branch is connected to the resonant unit in the first parallel branch, and the second end of inductor L1 is grounded. The first end of inductor L2 in the second parallel branch is connected to the resonant unit in the second parallel branch, and the second end of inductor L2 is grounded. The first end of inductor L3 in the third parallel branch is connected to the resonant unit in the third parallel branch, and the second end of inductor L3 is grounded. The first end of inductor L4 in the fourth parallel branch is connected to the resonant unit in the fourth parallel branch, and the second end of inductor L4 is grounded. The first end of inductor L5 in the fifth parallel branch is connected to the resonant unit in the fifth parallel branch, and the second end of inductor L5 is grounded. It is understood that any two of inductors L1, L2, L3, L4, and L5 can be coupled, or a T-type coupling grounding can be formed by sharing a common inductor.

[0029] Furthermore, the filter further comprises a first matching unit arranged between the input terminal IN and the filter network; and a second matching unit arranged between the filter network and the output terminal OUT. Figure 2As shown in FIG, the first matching unit includes an inductor Lin (i.e., a first matching inductor), and the second matching unit includes an inductor Lout_se (i.e., a second matching inductor) and an inductor Lout_sh (i.e., a third matching inductor). A first end of the inductor Lin is connected to the input terminal IN, and a second end of the inductor Lin is grounded. A first end of the inductor Lout_se is connected to the output terminal of the filter network, and a second end of the inductor Lout_se is connected to the output terminal OUT. A first end of the inductor Lout_sh is connected to the output terminal OUT, and a second end of the inductor Lout_sh is grounded. It should be noted that the inductor of the first matching unit and / or the second matching unit can also be a single lumped element (such as an inductor and / or a capacitor) connected in series with the series branch, or the first matching unit and / or the second matching unit can also be a resonant unit composed of a resonator with capacitive or inductive properties connected in series with the series branch; the first matching unit and / or the second matching unit can also be other lumped elements connected in parallel to the ground, such as a capacitor, an inductor, or a resonant unit with capacitive or inductive properties, and the first matching unit and the second matching unit can also form lumped elements such as capacitors and inductors into a form of one parallel and one series or one series and one parallel; the first matching unit can also be a resonant unit with more degrees of freedom. The first matching unit and the second matching unit are not further limited in the present invention.

[0030] It should be noted that when any three or more inductors are coupled in the circuit structure of the filter provided by the present invention, it is necessary to ensure that the current flows of the coupled inductors on the filter printed circuit board are not all set in the same direction. For example, the current flow direction of two of the inductors on the filter printed circuit board can be set to a first direction, and the current flow direction of the remaining inductors on the filter printed circuit board can be set to a second direction opposite to the first direction, to control out-of-band suppression.

[0031] In one embodiment, see Figure 3 , Figure 3 A schematic diagram showing the current flow between coupled inductors in an embodiment of the filter provided by the present invention is shown. Figure 3 As shown, there is coupling between the inductor L3, the inductor L5 and the inductor Lout_sh in the second matching unit. The current flow directions of the inductor L3 and the inductor L5 can be set to the same first direction, and the current flow direction of the inductor Lout_sh can be set to a second direction opposite to the first direction.

[0032] Furthermore, the relevant coupling can be regulated by adjusting the distance between the coupled inductors. More preferably, the relevant coupling can be regulated by preferentially adjusting the distance between the inductor whose current flow direction is different from that of the other inductors. For example, because the current flow direction of the inductor Lout_sh is different from that of the inductor L3 and the inductor L5, the mutual coupling can be regulated by adjusting the distance between the inductor Lout_sh in the parallel branch of the second matching unit and the two inductors L3 and L5 with the same current flow direction.

[0033] It is understandable that different couplings can also be achieved by adjusting the specific metal layer positions of the inductors with the same current flow direction in the coupled inductors on the filter printed circuit board. For example, the coupling can be adjusted by sharing the ground of the filter chip with the inductor L3 or the inductor L5.

[0034] In another embodiment, see Figure 4 , Figure 4 FIG. 1 is a schematic diagram showing the current flow between coupled inductors in another embodiment of the filter provided by the present invention. Figure 4 As shown, there is coupling between the inductor L3, the inductor L5 and the inductor Lout_se and the inductor Lout_sh in the second matching unit. The current flow direction of the inductor L3 and the inductor L5 can be set to the same as the first flow direction, and the current flow direction of the inductor Lout_se and the inductor Lout_sh can be set to the second flow direction opposite to the first flow direction.

[0035] In yet another embodiment, see Figure 5 , Figure 5 FIG. 1 is a schematic diagram showing the current flow between coupled inductors in another embodiment of the filter provided by the present invention. Figure 5 As shown, there is coupling between the inductor L3, the inductor L5 and the inductor Lout_se in the second matching unit. The current flow directions of the inductor L3 and the inductor Lout_se can be set to the same second direction, and the current flow direction of the inductor L5 can be set to a first direction opposite to the second direction.

[0036] The radio frequency filter provided by the utility model can realize the suppression requirements of different out-of-bands without affecting the Q value and the overall performance.

[0037] The filter of the embodiment of the present invention can further be widely used in communication devices, exemplified by mobile phones, personal digital assistants, electronic game devices, wearable terminals, etc.

[0038] The present invention has been described above with reference to specific embodiments. However, those skilled in the art should understand that these descriptions are merely illustrative and are not intended to limit the scope of protection of the present invention. Those skilled in the art may make various variations and modifications to the present invention based on the spirit and principles of the present invention, and such variations and modifications are also within the scope of the present invention.

Claims

1. A filter, characterized in that: include: An input terminal, an output terminal, a filter network, a first matching unit, and a second matching unit; the filter network is arranged between the input terminal and the output terminal and includes M series branches and N parallel branches, where M and N are natural numbers; the first matching unit is arranged between the input terminal and the filter network, and the second matching unit is arranged between the filter network and the output terminal; Each series branch includes a resonant unit, one end of the parallel branch is connected to a node between the series branches, and the other end of the parallel branch is grounded; each parallel branch, the first matching unit, and the second matching unit includes at least one inductor; When any three or more inductors in the filter are coupled, the current flows of the coupled inductors on the filter printed circuit board cannot all be arranged in the same direction.

2. The filter according to claim 1, wherein: The mutual coupling is regulated by adjusting the distance between the coupled inductor, whose current flow direction on the filter printed circuit board is different from that of the other inductors, and the other inductors.

3. The filter according to claim 1, wherein: Different couplings are achieved by adjusting the number of metal layers on the filter printed circuit board of the inductors with the same current flow direction in the coupled inductors.

4. The filter according to claim 3, wherein: The coupling is adjusted by grounding one of the coupled inductors with the same current flow direction to the ground of the filter chip.

5. The filter according to any one of claims 1 to 4, characterized in that: The filtering network constitutes a T-type filtering network, including 5 series branches and 5 parallel branches, each of the series branches and each parallel branch has a resonance unit, and the resonance unit is selected from: a resonance unit composed of LC lumped elements, a resonance unit composed of surface acoustic wave resonators, a resonance unit composed of bulk acoustic wave resonators, a resonance unit composed of LC lumped elements and surface acoustic wave resonators, a resonance unit composed of LC lumped elements and bulk acoustic wave resonators, and at least one resonance unit composed of surface acoustic wave resonators and bulk acoustic wave resonators.

6. The filter according to claim 5, wherein: A first end of the inductor L1 on the first parallel branch is connected to the resonant unit on the first parallel branch, and a second end of the inductor L1 is grounded; a first end of the inductor L2 on the second parallel branch is connected to the resonant unit on the second parallel branch, and a second end of the inductor L2 is grounded; a first end of the inductor L3 on the third parallel branch is connected to the resonant unit on the third parallel branch, and a second end of the inductor L3 is grounded; a first end of the inductor L4 on the fourth parallel branch is connected to the resonant unit on the fourth parallel branch, and a second end of the inductor L4 is grounded; A first end of the inductor L5 on the fifth parallel branch is connected to the resonant unit on the fifth parallel branch, and a second end of the inductor L5 is grounded.

7. The filter according to claim 6, wherein: The first matching unit includes a first matching inductor, and the second matching unit includes a second matching inductor and a third matching inductor, wherein the first end of the first matching inductor is connected to the input terminal, and the second end of the first matching inductor is grounded; the first end of the second matching inductor is connected to the output end of the filter network, and the second end of the second matching inductor is connected to the output terminal; the first end of the third matching inductor is connected to the output terminal, and the second end of the third matching inductor is grounded.

8. The filter according to claim 7, wherein: When coupling exists between the inductor L3, the inductor L5 and the third matching inductor, the current flow direction of the inductor L3 and the inductor L5 on the filter printed circuit board is set to a first flow direction, and the current flow direction of the third matching inductor on the filter printed circuit board is set to a second flow direction opposite to the first flow direction; or the current flow direction of the inductor L3 and the second matching inductor on the filter printed circuit board is set to the second flow direction, and the current flow direction of the inductor L5 on the filter printed circuit board is set to the first flow direction opposite to the second flow direction.

9. The filter according to claim 7, wherein: When coupling exists among the inductor L3, the inductor L5, the second matching inductor, and the third matching inductor, the current flow direction of the inductor L3 and the inductor L5 on the filter printed circuit board is set to a first flow direction, and the current flow direction of the second matching inductor and the third matching inductor on the filter printed circuit board is set to a second flow direction opposite to the first flow direction.

10. A communication device, characterized in that: The communication device comprises the filter according to any one of claims 1 to 9.

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