Structure for reducing incontinuity of impedance at equal-length position in differential wire winding pair and circuit board

Abstract

The utility model discloses a structure and a circuit board for reducing the impedance discontinuity at the inner equal-length part of a differential wire winding pair, which comprises a first transmission line and a second transmission line, the first transmission line is provided with an equal-length winding section, the equal-length winding section is provided with a first impedance adjusting part, and the second transmission line is provided with a second impedance adjusting part. The line width of the first impedance adjusting part is larger than that of other parts of the first transmission line, a second impedance adjusting part is arranged at the position, corresponding to the first impedance adjusting part, of the second transmission line, and the line width of the second impedance adjusting part is larger than that of other parts of the second transmission line. According to the utility model, the line widths of the first impedance adjusting part and the second impedance adjusting part are increased, and the impedance of the equilong winding sections is reduced, so that impedance abrupt change points caused by winding are slowed down or eliminated, the impedance of the whole differential line is more continuous and stable, adverse effects of signal reflection, crosstalk and the like are reduced, and the integrity and reliability of signals are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of differential lines, and more particularly to a structure and a circuit board for reducing impedance discontinuity at equal lengths within a differential line winding pair. Background Art

[0002] In PCB (printed circuit board) design, differential wiring technology is widely used for high-speed signal transmission, particularly in communication interfaces and high-speed digital systems. Differential wiring transmits signals via two coupled transmission lines (usually labeled P and N, or + and -). These two lines have equal amplitude but opposite phases, effectively reducing the effects of common-mode noise and improving the signal's immunity to interference.

[0003] However, during actual routing, differential lines often inevitably encounter turning points. At these turning points, the inner transmission line is shorter, while the outer differential line is longer, resulting in a length difference between the two. To meet the timing requirements of high-speed differential lines, equal-length windings are often added to the inner transmission line to compensate for the length difference.

[0004] Although equal-length winding can ensure the consistency of the total length of the P and N lines, winding will cause the distance between the two transmission lines to increase at the turning point, which in turn causes impedance discontinuity, affecting the signal transmission quality and possibly causing signal reflection, crosstalk and loss of signal integrity.

[0005] The above shortcomings need to be improved. Summary of the Invention

[0006] In order to solve or alleviate the problem of impedance discontinuity in equal-length winding segments of existing differential lines, the utility model provides a structure and a circuit board for reducing impedance discontinuity at equal-length locations within a differential line winding pair.

[0007] The technical solution of this utility model is as follows:

[0008] A structure and circuit board for reducing impedance discontinuity at equal lengths within a differential winding pair, comprising a first transmission line and a second transmission line. The first transmission line is provided with winding segments of equal length, each of which is provided with a first impedance adjustment portion, wherein the width of the first impedance adjustment portion is greater than the width of other portions of the first transmission line. A second impedance adjustment portion is provided at a position on the second transmission line corresponding to the first impedance adjustment portion, wherein the width of the second impedance adjustment portion is greater than the width of other portions of the second transmission line.

[0009] Furthermore, the trunk line width of the first transmission line is not less than 4 mil.

[0010] Furthermore, a first distance between the trunk line of the first transmission line and the trunk line of the second transmission line is not less than a width of the trunk line of the first transmission line.

[0011] Furthermore, a second distance between the first impedance adjustment portion and the second impedance adjustment portion is not greater than twice the first distance.

[0012] Furthermore, the length of the first impedance adjustment portion is not less than three times the trunk line width of the first transmission line.

[0013] Furthermore, the first impedance adjustment portion and the second impedance adjustment portion have the same length.

[0014] Furthermore, transition portions are provided at both ends of the first impedance adjustment portion and the second impedance adjustment portion, and the line width of the transition portion gradually increases from the trunk line width of the first transmission line to the line width of the first impedance adjustment portion.

[0015] Furthermore, the equal-length winding segment includes two inclined segments connected to the trunk line of the first transmission line and a parallel segment arranged between the two inclined segments, and the angle between the inclined segment and the trunk line of the first transmission line is 135°.

[0016] Furthermore, the first impedance adjustment portion is located in the parallel section, and the line width of the inclined section is equal to the line width of the trunk line of the first transmission line.

[0017] A circuit board comprises the above-mentioned structure for reducing impedance discontinuity at equal lengths within a differential winding pair.

[0018] The beneficial effect of the present invention according to the above scheme is that the present invention reduces the impedance of the winding segments of equal length by increasing the line width of the first impedance adjustment part and the second impedance adjustment part, thereby slowing down or eliminating the impedance mutation point caused by the winding, making the impedance of the overall differential line more continuous and stable, reducing adverse effects such as signal reflection and crosstalk, and thus improving the integrity and reliability of the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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 embodiments or the description of the prior art. 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 paying any creative work.

[0020] Figure 1 It is a structural diagram of the present utility model.

[0021] Among them, the reference numerals in the figure are: 1, first transmission line; 101, equal-length winding segment; 102, inclined segment; 103, parallel segment; 104, first impedance adjustment part; 105, transition part; 2, second transmission line; 201, second impedance adjustment part. DETAILED DESCRIPTION

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0023] It should be noted that when a component is referred to as being "fixed" or "set" or "connected" to another component, it may be located directly or indirectly on the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on this technical solution. The terms "first", "second", etc. are only used for the convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0024] like Figure 1 As shown, a structure for reducing impedance discontinuity at equal lengths within a differential winding pair, according to one embodiment of the present invention, includes a first transmission line 1 and a second transmission line 2. The first transmission line 1 is provided with an equal-length winding segment 101, and the equal-length winding segment 101 is provided with a first impedance adjustment portion 104. The line width of the first impedance adjustment portion 104 is greater than the line width of other locations on the first transmission line 1. A second impedance adjustment portion 201 is provided at a position on the second transmission line 2 corresponding to the first impedance adjustment portion 104. The line width of the second impedance adjustment portion 201 is greater than the line width of other locations on the second transmission line 2.

[0025] A first impedance adjustment section 104 is provided on the equal-length winding segment 101, with a line width greater than that of the rest of the first transmission line 1. Accordingly, a second impedance adjustment section 201 is provided on the second transmission line 2 at a location corresponding to the first impedance adjustment section 104, also with a line width greater than that of the rest of the second transmission line 2. Increasing the line width reduces the impedance of the transmission line, achieving impedance continuity. Simultaneously, adjusting the line spacing between the first impedance adjustment section 104 and the second impedance adjustment section 201 further optimizes the coupling effect between the differential lines, helping to maintain differential signal balance and reduce common-mode noise.

[0026] In this embodiment, by increasing the line width of the first impedance adjustment part 104 and the second impedance adjustment part 201, the impedance of the equal-length winding segment 101 is reduced, thereby slowing down or eliminating the impedance mutation point caused by winding, making the impedance of the overall differential line more continuous and stable, reducing adverse effects such as signal reflection and crosstalk, thereby improving signal integrity and reliability.

[0027] In a preferred embodiment, the trunk line width of the first transmission line 1 is not less than 4 mil.

[0028] In this embodiment, a trunk line width of 4 mil (i.e., 0.1 mm) or greater reduces the resistance of the first transmission line 1, thereby reducing signal attenuation during transmission, ensuring signal integrity and strength, and helping to maintain signal quality and reduce signal loss, especially in long-distance or high-frequency transmission scenarios. At the same time, a larger line width facilitates factory production, and the line width is related to the copper thickness of the differential trace layer. The thicker the copper thickness, the wider the line width needs to be. The specific size is calculated based on the impedance calculation tool and the impedance requirement.

[0029] In actual application, the trunk line width of the first transmission line 1 can be determined according to the factory's process capabilities and product requirements, and the specific size can be 2 mil, 3 mil, etc.

[0030] like Figure 1 As shown, in a preferred embodiment, the first spacing between the trunk line of the first transmission line 1 and the trunk line of the second transmission line 2 is not less than the trunk line width of the first transmission line 1 .

[0031] In this embodiment, increasing the first spacing can effectively improve the coupling effect between the differential lines. In differential signal transmission, the coupling between the two transmission lines is a key factor in maintaining signal balance and reducing common-mode noise. When the first spacing is not less than the trunk line width of the first transmission line 1, the coupling strength between the two transmission lines is optimized, which can not only ensure the tight synchronization of the differential signal, but also effectively suppress the impact of external interference on the signal, helping to improve the signal's anti-interference ability and transmission quality. In addition, a larger first spacing facilitates factory production, has lower requirements for production equipment, and has lower production costs.

[0032] Secondly, a larger first spacing also helps reduce crosstalk between differential lines. Crosstalk is a common signal interference issue in PCB design, especially in high-speed signal transmission. Increasing the first spacing reduces electromagnetic field interaction between the two transmission lines, thereby lowering the probability of crosstalk. This helps maintain signal clarity and integrity, improving the stability and reliability of the entire system.

[0033] like Figure 1As shown, in a preferred embodiment, the second distance between the first impedance adjustment portion 104 and the second impedance adjustment portion 201 is not greater than twice the first distance.

[0034] In this embodiment, controlling the second spacing to no more than twice the first spacing helps maintain the overall impedance continuity of the differential line pair. The impedance adjustment unit is used to compensate for impedance mismatch. By limiting the second spacing to a reasonable range, it can ensure appropriate electromagnetic field interaction between the impedance adjustment unit and the adjacent transmission line trunk, thereby avoiding unnecessary impedance changes or reflections, helping to maintain the transmission quality of the differential signal and reducing signal distortion and attenuation.

[0035] Secondly, a smaller second spacing also helps optimize the signal synchronization and common-mode suppression capabilities of the differential line pair. The advantage of differential signals is that they can use the signal differences between the two transmission lines to transmit information and effectively suppress common-mode noise. When the second spacing is appropriate, the coupling between the first impedance adjustment unit 104 and the second impedance adjustment unit 201 can further enhance the synchronization of the differential signal, while improving the suppression of common-mode noise, optimizing the signal transmission environment, and helping to improve the signal-to-noise ratio and signal integrity of the entire system.

[0036] like Figure 1 As shown, in a preferred embodiment, the length of the first impedance adjustment portion 104 is not less than three times the trunk line width of the first transmission line 1 .

[0037] In this embodiment, by providing a first impedance adjustment portion 104 of sufficient length, the impedance change can be made smoother, reducing signal reflection and loss caused by sudden changes. The smooth impedance transition helps maintain signal integrity and stability, which is particularly important in high-speed signal transmission. At the same time, the longer first impedance adjustment portion 104 is easy to produce, has lower requirements on production equipment, and has lower production costs.

[0038] like Figure 1 As shown, in a preferred embodiment, the first impedance adjustment portion 104 and the second impedance adjustment portion 201 have the same length.

[0039] In this embodiment, by making the first impedance adjustment portion 104 and the second impedance adjustment portion 201 of comparable length, it helps to ensure that the differential line pair has consistent impedance characteristics in the equal-length winding segments 101, thereby preventing impedance mismatch caused by length differences, helping to maintain the integrity and stability of the differential signal, and improving the quality of signal transmission.

[0040] like Figure 1As shown, in a preferred embodiment, transition portions 105 are respectively provided at both ends of the first impedance adjustment portion 104 and the second impedance adjustment portion 201 , and the line width of the transition portion 105 gradually increases from the trunk line width of the first transmission line 1 to the line width of the first impedance adjustment portion 104 .

[0041] In the above technical description, transition sections 105 are introduced, which are respectively provided at both ends of the first impedance adjustment section 104 and the second impedance adjustment section 201. The line width of these transition sections 105 gradually increases from the line width of the main line of the first transmission line 1 to the line width of the first impedance adjustment section 104. This design brings the following significant technical effects:

[0042] In this embodiment, a smooth transition of impedance is achieved by providing a transition portion 105. In PCB design, when the line width of the transmission line suddenly changes, it often leads to impedance discontinuity, which in turn causes signal reflection and loss. By providing a transition portion 105 between the impedance adjustment portion and the trunk line and gradually increasing its line width, the rate of impedance change can be effectively slowed down, making the impedance transition smoother, helping to reduce reflection and loss of the signal during transmission and improving the transmission quality of the signal. Secondly, the transition portion 105 makes the impedance change smoother, so that the differential signal can maintain a more stable waveform and phase relationship during transmission, reducing signal distortion and phase shift caused by impedance discontinuity, improving the signal's anti-interference ability and reliability, and enhancing the stability and reliability of the differential signal.

[0043] like Figure 1 As shown, in a preferred embodiment, the equal-length winding segment 101 includes two inclined segments 102 connected to the trunk line of the first transmission line 1 and a parallel segment 103 arranged between the two inclined segments 102, and the angle between the inclined segment 102 and the trunk line of the first transmission line 1 is 135°.

[0044] The first impedance adjustment portion 104 is located in the parallel section 103 , and the line width of the inclined section 102 is equal to the line width of the trunk line of the first transmission line 1 .

[0045] In this embodiment, the 135° angle not only complies with the recommended routing rules in most PCB design software, facilitating design, but also helps achieve smooth transitions in signal transmission paths. This reduces signal reflections and crosstalk caused by sudden angle changes, improving signal integrity and signal-to-noise ratio, and ensuring stable and reliable high-speed signal transmission. Furthermore, a larger angle prevents "sour angles." At smaller routing angles, the topographical solution can accumulate at transitions, leading to excessive corrosion.

[0046] Secondly, as the relatively stable portion of the equal-length winding segment 101, the impedance characteristics of the parallel segment 103 are easier to control. Placing the impedance adjustment unit here allows for more precise adjustment of the impedance of this area, aligning it with the impedance of the main line and other components. Furthermore, the line width of the inclined segment 102 is consistent with that of the main line, ensuring a smooth impedance transition across the entire equal-length winding segment 101, further improving signal transmission quality.

[0047] A circuit board in one embodiment of the present invention includes the above-mentioned structure for reducing impedance discontinuity at equal lengths within a differential winding pair.

[0048] In this embodiment, the aforementioned differential line structure maintains impedance continuity and consistency during the differential line's routing, reducing reflection, attenuation, and distortion during signal transmission, thereby ensuring the integrity and stability of the differential signal. Therefore, this circuit board is particularly suitable for applications requiring high signal quality, such as high-speed data transmission and high-frequency signal processing.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A structure for reducing impedance discontinuity at equal lengths within a differential winding pair, characterized in that: The invention comprises a first transmission line and a second transmission line, wherein the first transmission line is provided with an equal-length winding segment, the equal-length winding segment is provided with a first impedance adjustment part, the line width of the first impedance adjustment part is greater than the line width of other parts of the first transmission line, and the second transmission line is provided with a second impedance adjustment part at a position corresponding to the first impedance adjustment part, the line width of the second impedance adjustment part is greater than the line width of other parts of the second transmission line.

2. A structure for reducing impedance discontinuity at equal lengths within a differential winding pair according to claim 1, characterized in that: The trunk line width of the first transmission line is not less than 4 mil.

3. The structure for reducing impedance discontinuity at equal lengths within a differential winding pair according to claim 1, wherein: A first distance between the trunk line of the first transmission line and the trunk line of the second transmission line is not less than a line width of the trunk line of the first transmission line.

4. The structure for reducing impedance discontinuity at equal lengths within a differential winding pair according to claim 3, wherein: A second distance between the first impedance adjustment portion and the second impedance adjustment portion is no greater than twice the first distance.

5. The structure for reducing impedance discontinuity at equal lengths within a differential winding pair according to claim 1, wherein: The length of the first impedance adjustment portion is not less than three times the trunk line width of the first transmission line.

6. The structure for reducing impedance discontinuity at equal lengths within a differential winding pair according to claim 1, wherein: The first impedance adjusting portion and the second impedance adjusting portion have the same length.

7. The structure for reducing impedance discontinuity at equal lengths within a differential winding pair according to claim 1, wherein: Transition portions are respectively provided at both ends of the first impedance adjustment portion and the second impedance adjustment portion, and the line width of the transition portion gradually increases from the trunk line width of the first transmission line to the line width of the first impedance adjustment portion.

8. The structure for reducing impedance discontinuity at equal lengths within a differential winding pair according to claim 1, wherein: The equal-length winding segments include two inclined segments connected to the trunk line of the first transmission line and a parallel segment arranged between the two inclined segments. The angle between the inclined segment and the trunk line of the first transmission line is 135°.

9. The structure for reducing impedance discontinuity at equal lengths within a differential winding pair according to claim 8, wherein: The first impedance adjustment portion is located in the parallel section, and the line width of the inclined section is equal to the line width of the trunk line of the first transmission line.

10. A circuit board, characterized in that: The invention comprises the structure for reducing impedance discontinuity at equal lengths within a differential winding pair as described in any one of claims 1 to 9.

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