Low-pass filter for FTTR (Fiber To The Rate) equipment, PCB (Printed Circuit Board) and FTTR equipment
By integrating printed microstrip lines onto a PCB substrate to form a filter, the problem of requiring additional components in traditional filters is solved, achieving a highly integrated and low-cost filter design suitable for fiber-to-the-room (FTTR) equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN SKYWORTH DIGITAL TECH CO LTD
- Filing Date
- 2025-03-24
- Publication Date
- 2026-04-17
AI Technical Summary
Traditional low-pass filters with lumped element design and cavity design require additional components, resulting in slightly lower integration.
A filter is formed by integrating printed microstrip lines on a PCB substrate. By utilizing the distributed parameter characteristics of the microstrip lines on the PCB substrate and combining methods such as Richard transform calibration, a corresponding filter microstrip line structure is formed to realize the filter function, such as the function of a low-pass filter.
This improves the integration of filters, reduces costs and manufacturing complexity, eliminates the need for additional components, and meets the requirements of high-performance applications.
Smart Images
Figure CN224138308U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of fiber-to-the-room (FTTR) technology, and in particular to a low-pass filter, PCB board, and FTTR device for FTTR equipment. Background Technology
[0002] A microwave filter is a module used to select or suppress microwave signals within a specific frequency range. It is widely used in communications, radar, and satellite systems, and specifically in hardware products such as Fiber to the Room (FTTR), Fiber to the Room-Business (FTTR-B), and broadband converged terminals. Based on their frequency response characteristics, microwave filters can be classified into low-pass, high-pass, band-pass, and band-stop filters.
[0003] Common design approaches include lumped-element low-pass filters, which use lumped components such as inductors and capacitors and are suitable for low-frequency microwave filters; and cavity filters, which use resonant cavities and have low insertion loss, suitable for high-performance applications. However, the capacitors and inductors used in lumped-element designs have only a limited range of values in the microwave band and are more suitable for low-frequency bands; while cavity filters offer good performance, they have requirements for the component structure and the components are expensive; moreover, both lumped-element and cavity designs require additional components, resulting in slightly lower integration.
[0004] Utility Model Content
[0005] This utility model relates to the field of fiber-to-the-room (FTTR) technology, and provides a low-pass filter, PCB board and FTTR device for FTTR equipment, to solve the technical problem that traditional low-pass filters with lumped component design and cavity design require additional components and have slightly poor integration.
[0006] A filter for use in fiber-to-the-room (FTTR) equipment, the filter being formed by printed microstrip lines integrated on a PCB substrate, the filter comprising:
[0007] The microstrip distribution element includes a central microstrip line portion distributed in a square wave shape, and a first side microstrip line portion and a second side microstrip line portion located at both ends of the central microstrip line portion, wherein the first end of the central microstrip line portion is connected to the first end of the first side microstrip line portion to form a first signal terminal of the microstrip distribution element, and the second end of the central microstrip line portion is connected to the first end of the second side microstrip line portion to form a second signal terminal of the microstrip distribution element;
[0008] The second end of the first side microstrip line portion and the second end of the second side microstrip line portion are in a suspended state.
[0009] Furthermore, the first side-end microstrip line portion and the second side-end microstrip line portion are symmetrically distributed.
[0010] Furthermore, the first side-end microstrip line portion includes a curved line segment formed by a first microstrip line, a second microstrip line, a third microstrip line, and a fourth microstrip line. The first microstrip line is perpendicular to the first end of the middle microstrip line portion. The first microstrip line, the second microstrip line, the third microstrip line, and the fourth microstrip line are perpendicular to each other in sequence, and a notch is formed between the second microstrip line, the third microstrip line, and the fourth microstrip line. The notches formed by the first side-end microstrip line portion and the second side-end microstrip line portion are distributed opposite to each other.
[0011] Furthermore, the first side-end microstrip line portion includes a right-angled line segment formed by a fifth microstrip line and a sixth microstrip line. The fifth microstrip line is perpendicular to the first end of the middle microstrip line portion. The fifth microstrip line and the sixth microstrip line are perpendicular to each other and form a vertical angle between them. The vertical angles formed by the first side-end microstrip line portion and the second side-end microstrip line portion are relatively distributed.
[0012] Furthermore, the linewidth of the first side-end microstrip line portion and the second side-end microstrip line portion is 0.34 mm, the linewidth of the middle microstrip line portion is 0.16 mm, and the distance between the first end and the second end of the middle microstrip line portion is 6.44 mm.
[0013] Further, the filter includes one of the microstrip distribution elements; or, the filter includes a combined microstrip distribution element, which includes a plurality of microstrip distribution elements arranged in sequence, wherein the first signal terminal of the first microstrip distribution element is the first signal terminal of the combined microstrip distribution element, the second signal terminal of the last microstrip distribution element is the second signal terminal of the combined microstrip distribution element, and the signal terminals of the microstrip distribution elements between the first and last positions are connected in sequence.
[0014] Furthermore, the mid-range microstrip line portion includes two recessed notches.
[0015] A PCB board includes a PCB substrate and a filter formed by printed microstrip lines integrated on the PCB substrate, wherein the filter is any of the filters described above.
[0016] Furthermore, the thickness of the PCB substrate is 1.2 mm.
[0017] An FTTR device includes a PCB board as described in any of the preceding claims.
[0018] The aforementioned solution provides a filter formed by printed microstrip lines integrated onto a PCB substrate. Therefore, by utilizing the distributed parameter characteristics of the microstrip lines on a specific PCB structure, combined with methods such as Richard transform calibration, the capacitive and inductive properties required for the corresponding filter design can be equivalently derived from the microstrip lines on the PCB substrate, forming the corresponding filter microstrip line circuit structure. This achieves the filter's function, such as a low-pass filter, to suppress high-order harmonic power. Furthermore, since it utilizes microstrip lines on a specific PCB structure to form the circuit filter, it can be integrated during the PCB layout process, meaning it's integrated into the PCB manufacturing process without requiring additional components. This offers significant advantages in cost and manufacturing. It also solves the technical problem that traditional lumped-element and cavity-designed low-pass filters require additional components and have slightly lower integration, thus improving the filter's integration level. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of a filter structure according to one embodiment of the present invention;
[0021] Figure 2 This is a schematic diagram showing a filter integrated on a PCB substrate in one embodiment of the present invention;
[0022] Figure 3 This is a schematic diagram of a filter and its modified structure according to an embodiment of the present invention;
[0023] Figure 4 This is a schematic diagram of another structure of a filter according to one embodiment of the present invention;
[0024] Figure 5 This is a schematic diagram of the microstrip linewidth in a filter according to one embodiment of the present invention;
[0025] Figure 6 This is a schematic diagram of a PCB board that does not use a filter provided in the embodiments of this application;
[0026] Figure 7 This is a schematic diagram of a PCB board using a filter provided in an embodiment of this application;
[0027] Figure 8 This is a schematic diagram of experimental results without using a filter provided in the embodiments of this application;
[0028] Figure 9 This is a schematic diagram of another experimental result that does not use a filter provided in the embodiments of this application.
[0029] In the picture:
[0030] 11-First side-end microstrip line section; 111-First microstrip line; 112-Second microstrip line; 113-Third microstrip line; 114-Fourth microstrip line; 115-Fifth microstrip line; 116-Sixth microstrip line;
[0031] 12 - Mid-range microstrip circuit section;
[0032] 13-Third side end microstrip circuit section. Detailed Implementation
[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.
[0034] It should be understood that this invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this invention to those skilled in the art. In the drawings, for clarity, the dimensions of layers and regions, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.
[0035] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this utility model, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.
[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.
[0037] To fully understand this utility model, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by this utility model. Preferred embodiments of this utility model are described in detail below; however, in addition to these detailed descriptions, this utility model may have other embodiments.
[0038] Please refer to the online guide. Figure 1 As shown, this application provides a filter for use in hardware products such as Fiber to the Room (FTTR), Fiber to the Room-Business (FTTR-B), and broadband converged terminals. For example, this filter can be a low-pass filter, wherein the filter is formed by printed microstrip lines integrated on a PCB substrate, and is a line filter formed during the PCB printing process.
[0039] like Figure 1As shown, the filter includes a microstrip distribution element, which includes a central microstrip line portion 12 arranged in a square wave shape, and a first side microstrip line portion 11 and a second side microstrip line portion 13 located at both ends of the central microstrip line portion. The first end of the central microstrip line portion 12 is connected to the first end of the first side microstrip line portion 11 to form a first signal terminal of the microstrip distribution element, and the second end of the central microstrip line portion 12 is connected to the first end of the second side microstrip line portion 13 to form a second signal terminal of the microstrip distribution element.
[0040] The second end of the first side microstrip line portion 11 and the second end of the second side microstrip line portion 13 are in a suspended state.
[0041] This embodiment provides a filter for use in hardware products such as Fiber to the Room (FTTR), enterprise-level FTTR-B equipment, and broadband converged terminals. This filter is formed by printed microstrip lines integrated onto a PCB substrate. Therefore, by utilizing the distributed parameter characteristics of the microstrip lines on the PCB substrate within a specific PCB structure, combined with methods such as Richard transform calibration, the capacitive and inductive properties required for the corresponding filter design can be equivalently derived from the microstrip lines on the PCB substrate, forming the corresponding filter microstrip line circuit structure. This achieves the filter's function, such as a low-pass filter, to suppress high-order harmonic power. Furthermore, since it is a circuit filter formed using microstrip lines on a specific PCB structure, it can be integrated during the PCB layout process, meaning it's integrated into the PCB manufacturing process without the need for additional components. This offers significant advantages in cost and manufacturing. It also solves the technical problem that traditional lumped-element and cavity-designed low-pass filters require additional components and have slightly lower integration, thus improving the filter's integration level.
[0042] In one embodiment, such as Figure 1 As shown, the first side-end microstrip line portion 11 and the second side-end microstrip line portion 13 are symmetrically distributed; the symmetrical design is beneficial for designing and adjusting the parameters of the formed filter.
[0043] It should be noted that the components of the microstrip line in this filter can have different geometric shapes to adapt to actual filter requirements.
[0044] In one embodiment, such as Figure 1 or Figure 3The diagram illustrates a microstrip line structure design for one type of microstrip distribution element. The first side-end microstrip line portion 11 includes a curved segment formed by a first microstrip line 111, a second microstrip line 112, a third microstrip line 113, and a fourth microstrip line 114. The first microstrip line 111 is perpendicular to the first end of the middle-end microstrip line portion 12. The first microstrip line 111, the second microstrip line 112, the third microstrip line 113, and the fourth microstrip line 114 are sequentially perpendicular to each other, and a notch is formed between the second microstrip line 112, the third microstrip line 113, and the fourth microstrip line 114. Similarly, since the second side-end microstrip line portion 12 and the first side-end microstrip line portion 11 are symmetrically designed, they have the same structural design as the first side-end microstrip line portion 11, which will not be elaborated here; the two are mirror images of each other. The notches formed by the first side-end microstrip line portion 11 and the second side-end microstrip line portion 12 are distributed opposite to each other, that is, the notches formed by the first side-end microstrip line portion 11 and the second side-end microstrip line portion 12 do not face each other. Specifically, as shown below... Figure 1 or Figure 3 As shown.
[0045] In one embodiment, such as Figure 3 As shown, Figure 3 The image shows a modified design of the first side-end microstrip line portion 11 and the second side-end microstrip line portion 12, representing another microstrip line structure design for a microstrip distribution element. The first side-end microstrip line portion 11 includes a right-angled line segment formed by a fifth microstrip line 115 and a sixth microstrip line 116. The fifth microstrip line 115 is perpendicular to the first end of the middle microstrip line portion 12. The fifth microstrip line 115 and the sixth microstrip line 116 are perpendicular to each other, forming a vertical angle between them. The vertical angles formed by the first side-end microstrip line portion 11 and the second side-end microstrip line portion 12 are relatively distributed, meaning that the right angles formed by the first side-end microstrip line portion 11 and the second side-end microstrip line portion 12 are facing each other. Specifically, as shown below... Figure 3 The substitution relationship is shown in the middle circle.
[0046] In this embodiment, at least two structural forms of microstrip distributed elements integrated on PCB substrates are provided to ensure the feasibility of the solution; in addition, a suitable filter can be selected according to the actual filter design requirements and PCB characteristics.
[0047] In one embodiment, the filter includes one of the microstrip distribution elements; or, as... Figure 4As shown, the filter includes a combined microstrip distribution element, which comprises a plurality of microstrip distribution elements arranged sequentially. The first signal terminal of the first microstrip distribution element is the first signal terminal of the combined microstrip distribution element, and the second signal terminal of the last microstrip distribution element is the second signal terminal of the combined microstrip distribution element. The signal terminals of the microstrip distribution elements between the first and last elements are connected sequentially. For example, exemplarily, there can be five such elements. Figure 1 or Figure 3 The microstrip distribution element shown is configured such that the first signal terminal of the first microstrip distribution element serves as the first signal terminal of the combined microstrip distribution element; the second signal terminal of the first microstrip distribution element is connected to the first signal terminal of the second microstrip distribution element; the second signal terminal of the second microstrip distribution element is connected to the first signal terminal of the third microstrip distribution element; the second signal terminal of the third microstrip distribution element is connected to the first signal terminal of the fourth microstrip distribution element; the second signal terminal of the fourth microstrip distribution element is connected to the first signal terminal of the fifth microstrip distribution element; and the second signal terminal of the fifth microstrip distribution element serves as the second signal terminal of the combined microstrip distribution element. For other quantities, the connection relationships follow the same pattern, and are not illustrated here.
[0048] In this embodiment, multiple microstrip distributed element units can be used in combination to form a combined microstrip distributed element to meet the filtering parameter requirements of different products.
[0049] In one embodiment, the mid-range microstrip line portion 12 includes two recessed notches, such as... Figure 3 As shown.
[0050] It should be noted that for more detailed shape information, please refer to the accompanying drawings; they will not be described in words here.
[0051] In one embodiment, such as Figure 1 as well as Figure 2 As shown, the linewidth of the first side-end microstrip line portion 11 and the second side-end microstrip line portion 13 is 0.34 mm, the linewidth of the middle microstrip line portion 12 is 0.16 mm, and the distance L between the first end and the second end of the middle microstrip line portion 12 is 6.44 mm. It should be noted that this embodiment specifically defines the linewidth design for different positions of the microstrip distribution element. Experiments have shown that the above design has good filtering characteristics in actual products.
[0052] It is worth noting that, such as Figure 4 As shown, in some embodiments, the specific linewidth of the microstrip distribution element can also be changed. Figure 4In the diagram, H1 represents the height of the reference layer in the current PCB board, Er1 represents the cross-section, and the linewidths W1 and W2 of the microstrip distribution element can be changed. T1 represents the height of the microstrip line of the cross-section microstrip distribution element exposed above the reference layer.
[0053] like Figure 6 and Figure 7 This is a PCB board diagram of one of the designs provided in this embodiment. Figure 6 This represents the original state of the PCB board. Figure 7 A PCB board integrating one of the filters provided in the embodiments of this application includes a PCB substrate and a microstrip printed circuit of copper foil, the microstrip printed circuit forming the filter in the embodiments of this application. As an example, the PCB motherboard may be a standard FR4 board, a 4-layer board, with a board thickness of 1.2 mm.
[0054] As an example, this filter can be a low-pass filter for the 2.4 GHz Wi-Fi band, with no signal attenuation in the 2.412-2.482 GHz range, and attenuation greater than 15 dB for the second and third harmonics. The area on the board can be as follows: Figure 1 As shown, the board structure is 6.44mm*4.47mm with 50 ohms RF impedance matching.
[0055] As an example scenario, this filter can be a low-pass filter, based on a 3rd-order Chebyshev LPF design. By appropriately selecting the cutoff frequency fc and utilizing the distributed parameter characteristics of the microstrip line on the PCB stack structure, the filter's design parameters can be calibrated. The Richard transform principle is used for parameter transformation, and finally, the impedance value of the microstrip line is calculated. Simultaneously, to reduce the board area, a curved layout is adopted to complete the design. The laboratory results meet expectations. The design results and actual test effects are as follows: Figure 8 and 9 As shown. Figure 8 The experimental results are for the filter not provided in the embodiments of this application. Figure 9 The experimental results are shown below, employing the filter provided in the embodiments of this application. It can be seen that, as... Figure 8 As shown, in the 2.4-2.5GHz operating frequency band: S11 < -20dB (matching a 50-ohm RF system), S21 > -0.5dB (small transmission attenuation); for the second harmonic (4.8GHz), S21 < -20dB; for the third harmonic (7.2GHz), S21 < -17dB (suppression of higher harmonic power is greater than 15dB). Here, S11 represents the input reflection coefficient of the first signal port, and S21 represents the forward transmission coefficient / gain. Furthermore, while ensuring stable power in the communication frequency band, it significantly suppresses the second and third harmonic power (e.g., ...). Figure 8 and 9(As shown), this ensures that the overall performance of the machine meets regulatory requirements.
[0056] It should be noted that the above-mentioned filter linewidth and other parameters are merely illustrative examples and do not limit the embodiments of this application.
[0057] In one embodiment, a PCB board is also provided, such as Figure 1 , Figure 7 As shown, the PCB board includes a PCB substrate and a filter formed by printed microstrip lines integrated on the PCB substrate, wherein the filter is the filter described in any of the foregoing embodiments.
[0058] In one embodiment, the thickness of the PCB substrate is 1.2 mm.
[0059] In one embodiment, an FTTR device is also provided, including a PCB board as described in the foregoing embodiments.
[0060] This invention provides a PCB board and an FTTR device. The filter used in both the PCB board and the FTTR device is a filter formed by printed microstrip lines integrated on the PCB substrate. Utilizing the distributed parameter characteristics of the microstrip lines on the PCB substrate within a specific PCB structure, and combining methods such as Richard transform calibration, the capacitive and inductive properties required for the corresponding filter design are equivalently derived from the microstrip lines on the PCB substrate, forming the corresponding filter microstrip line circuit structure. This achieves the filter function, such as the function of a low-pass filter, to suppress high-order harmonic power. Furthermore, since the filter is formed by microstrip lines on the PCB substrate within a specific PCB structure, it can be integrated during the PCB layout process, meaning it is integrated into the PCB manufacturing process without the need for additional components. This offers significant advantages in cost and manufacturing. It also solves the technical problem that traditional lumped component designs and cavity designs for low-pass filters require additional components and have slightly lower integration levels. This reduces the material cost and layout space of the PCB board, improving the integration level of the PCB board and the FTTR device.
[0061] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.
Claims
1. A filter applied to a fiber to the room (FTTR) device, characterized in that, The filter is formed by printed microstrip lines integrated on a PCB substrate, and the filter includes: A microstrip distribution element includes a central microstrip line portion distributed in a square wave shape, and a first side microstrip line portion and a second side microstrip line portion located at both ends of the central microstrip line portion, wherein a first end of the central microstrip line portion is connected to a first end of the first side microstrip line portion to form a first signal terminal of the microstrip distribution element, and a second end of the central microstrip line portion is connected to a first end of the second side microstrip line portion to form a second signal terminal of the microstrip distribution element; The second end of the first side microstrip line portion and the second end of the second side microstrip line portion are in a suspended state.
2. The filter of claim 1, wherein, The first side-end microstrip line portion and the second side-end microstrip line portion are symmetrically distributed.
3. The filter of claim 2, wherein, The first side-end microstrip line portion includes a curved line segment formed by a first microstrip line, a second microstrip line, a third microstrip line, and a fourth microstrip line. The first microstrip line is perpendicular to the first end of the middle microstrip line portion. The first microstrip line, the second microstrip line, the third microstrip line, and the fourth microstrip line are perpendicular to each other in sequence, and a notch is formed between the second microstrip line, the third microstrip line, and the fourth microstrip line. The notches formed by the first side-end microstrip line portion and the second side-end microstrip line portion are distributed opposite to each other.
4. The filter of claim 2, wherein, The first side-end microstrip line portion includes a right-angle line segment formed by a fifth microstrip line and a sixth microstrip line. The fifth microstrip line is perpendicular to the first end of the middle microstrip line portion. The fifth microstrip line and the sixth microstrip line are perpendicular to each other and form a vertical angle between them. The vertical angles formed by the first side-end microstrip line portion and the second side-end microstrip line portion are relatively distributed.
5. The filter of claim 2, wherein, The linewidth of the first side-end microstrip line portion and the second side-end microstrip line portion is 0.34 mm, the linewidth of the middle microstrip line portion is 0.16 mm, and the distance between the first end and the second end of the middle microstrip line portion is 6.44 mm.
6. The filter of claim 2, wherein, The filter includes one microstrip distribution element; or, the filter includes a combined microstrip distribution element, which includes a plurality of microstrip distribution elements arranged in sequence, wherein the first signal terminal of the first microstrip distribution element is the first signal terminal of the combined microstrip distribution element, the second signal terminal of the last microstrip distribution element is the second signal terminal of the combined microstrip distribution element, and the signal terminals of the microstrip distribution elements between the first and last positions are connected in sequence.
7. The filter of claim 2, wherein, The mid-range microstrip line section includes two recessed notches.
8. A PCB assembly, characterized by The filter includes a PCB substrate and a printed microstrip line integrated on the PCB substrate, the filter being the filter as described in any one of claims 1-7.
9. The PCB board piece of claim 8, wherein, The thickness of the PCB substrate is 1.2 mm.
10. An FTTR device, characterized by, Includes the PCB board as described in any one of claims 8-9.