Packaging structure for reducing high-speed signal crosstalk around AC coupling capacitor

Abstract

The utility model discloses a packaging structure for reducing high-speed signal crosstalk around AC coupling capacitors, a circuit board body comprises AC coupling capacitor pads arranged in pairs, and reference planes of the AC coupling capacitor pads are hollowed on a GND layer adjacent to the AC coupling capacitor pads; high-speed signal line via hole bonding pads are arranged at the two ends of each pair of AC coupling capacitor bonding pads, grounding holes are formed in the peripheries of the AC coupling capacitor bonding pads and the high-speed signal line via hole bonding pads, and the grounding holes correspond to the AC coupling capacitor bonding pads and the high-speed signal line via hole bonding pads in a one-to-one mode. The grounding holes are formed around the AC coupling capacitor bonding pad and the high-speed signal line via hole bonding pad, the grounding holes can effectively absorb electromagnetic radiation of high-speed signals, so that crosstalk is reduced, the reference plane of the GND layer adjacent to the AC coupling capacitor is hollowed out, the grounding holes additionally arranged nearby can reduce a backflow path of plane jumping, and the crosstalk is reduced. And the signal flows back through a nearby grounding hole during layer change, so that crosstalk is further reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of PCB design, and in particular to a packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor. Background Art

[0002] In order to meet consumers' demand for small electronic products and no-delay information transmission, high-speed serial links are increasingly used. With the development of high-speed serial links, AC coupling capacitors are also increasingly used. The main function of AC coupling capacitors is to allow AC signals to pass through and block DC signals, remove the DC bias component in the signal, and allow high-frequency components to pass smoothly. It is similar to a high-bandwidth filter and plays an important role in high-speed signal transmission electronic circuits.

[0003] However, in high-speed circuits, due to the complex frequency components of the signal, the charging and discharging process of the capacitor may not be able to quickly follow the changes in the signal, resulting in reflection and refraction of the signal at both ends of the capacitor. In addition, in high-speed circuits, the faster signal propagation speed makes the introduction of the capacitor change the propagation path and speed of the signal, which may cause the signal to have a phase difference and amplitude change around the capacitor, thereby causing signal crosstalk. Signal crosstalk will cause changes in the signal waveform, causing the signal to lose its original characteristics, resulting in signal distortion, and may also introduce noise. The increase in noise will reduce the signal-to-noise ratio of the signal, reduce the signal quality, and cause data transmission errors or system instability. Reducing the crosstalk of the coupling capacitor has a positive effect on improving the high-quality transmission of high-speed signals.

[0004] In order to reduce the generation of high-speed signal crosstalk, optimization measures such as adding a shielding layer and changing the wiring method are often used. However, adding a shielding layer and changing the wiring method will increase production costs and are not conducive to its widespread use. Utility Model Content

[0005] In order to overcome the disadvantage of high cost in reducing crosstalk around AC coupling capacitors of high-speed signals in the prior art, the utility model provides a packaging structure for reducing crosstalk around AC coupling capacitors of high-speed signals.

[0006] The technical solution of the utility model is as follows:

[0007] A packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor, comprising AC coupling capacitor pads arranged in pairs on a circuit board body, and a reference plane of the AC coupling capacitor pads is hollowed out on a GND layer adjacent to the AC coupling capacitor pads, characterized in that high-speed signal line via pads are provided at both ends of each pair of AC coupling capacitor pads, grounding holes are provided around the AC coupling capacitor pads and the high-speed signal line via pads, and the grounding holes are respectively arranged in one-to-one correspondence with the AC coupling capacitor pads and the high-speed signal line via pads.

[0008] Furthermore, in one embodiment, the grounding holes are arranged on both sides of the AC coupling capacitor pad and the high-speed signal line via pad, and the grounding holes on both sides are symmetrical about the AC coupling capacitor pad.

[0009] Furthermore, in one embodiment, the grounding hole includes a first grounding hole arranged outside the AC coupling capacitor pad, and a second grounding hole arranged outside the high-speed signal line via pad, and the diameter of the second grounding hole is larger than the diameter of the first grounding hole.

[0010] Furthermore, in one embodiment, the diameter of the first grounding hole is 16 mil, and the diameter of the second grounding hole is 18 mil.

[0011] Further, in one embodiment, the minimum distance between the edge of the AC coupling capacitor pad and the edge of the first ground hole is Z, 4.5≤Z≤8, and the unit is mil.

[0012] Furthermore, in one embodiment, there are four AC coupling capacitor pads arranged in a 2×2 matrix, and the center distance between two high-speed signal line via pads at the same end is X1, 26≤X1≤30, in mils.

[0013] Furthermore, in one embodiment, the diameter of the second grounding hole is the same as the outer diameter of the high-speed signal line via pad, and the center distance between adjacent second grounding holes and the high-speed signal line via pad is X2, X2=X1.

[0014] Furthermore, in one embodiment, the centers of the two high-speed signal line via pads at the same end are on the same straight line L, the center of the first grounding hole close to the straight line L is Y1 away from the straight line L, and the distance between the center of the second grounding hole close to the straight line L and the straight line L is Y2, and Y1=Y2.

[0015] Furthermore, in one embodiment, the minimum spacing between the edge of the high-speed signal line via pad and the edge of the AC coupling capacitor is K, 8≤K≤12, and the unit is mil.

[0016] Further, in one embodiment, the AC coupling capacitor pad is suitable for welding a 0201 coupling capacitor or a 0402 coupling capacitor.

[0017] According to the above scheme, the utility model has the beneficial effect that grounding holes are set around the AC coupling capacitor pad and the high-speed signal line via pad, and the grounding holes can effectively absorb the electromagnetic radiation of the high-speed signal, thereby reducing crosstalk. And because the reference plane of the GND layer adjacent to the AC coupling capacitor is hollowed out, the grounding holes added nearby can reduce the return path of this part of the plane jump, and the signal returns through the nearby grounding holes when changing layers. Therefore, the packaging structure for reducing the crosstalk of high-speed signals around the AC coupling capacitor described in this application can reduce the crosstalk around the AC coupling capacitor as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the utility model.

[0019] In the figure, 1, circuit board body; 2, AC coupling capacitor pad; 3, high-speed signal line via pad; 4, grounding hole; 401, first grounding hole; 402, second grounding hole. DETAILED DESCRIPTION

[0020] The utility model is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The terms "vertical", "horizontal", "left", "right", "inside", "outside" and similar expressions used in this specification are for illustrative purposes only. In the description of the utility model, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, unless otherwise specified, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; the meaning of "multiple" is two or more. The term "include" and any variation thereof means non-exclusive inclusion, and one or more other features, integers, steps, operations, units, components and / or combinations thereof may be present or added.

[0021] In addition, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or a connection between two components. All technical and scientific terms used in this specification have the same meaning as those generally understood by technicians in the technical field of the present utility model. The terms used in the specification of the present utility model are only for the purpose of describing specific embodiments and are not used to limit the present utility model. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0022] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] like Figure 1 As shown, the present application provides a packaging structure for reducing the crosstalk of high-speed signals around AC coupling capacitors. The circuit board body 1 includes AC coupling capacitor pads arranged in pairs. On the GND layer adjacent to the AC coupling capacitor pads, the reference plane of the AC coupling capacitor pads is hollowed out; both ends of each pair of AC coupling capacitor pads are provided with high-speed signal line via pads 3, and grounding holes 4 are provided around the AC coupling capacitor pads and the high-speed signal line via pads 3. The grounding holes 4 are respectively arranged in a one-to-one correspondence with the AC coupling capacitor pads and the high-speed signal line via pads 3. The grounding holes 4 are arranged around the AC coupling capacitor pads and the high-speed signal line via pads 3, and the grounding holes 4 can effectively absorb the electromagnetic radiation of the high-speed signal, thereby reducing the crosstalk. And because the reference plane of the GND layer adjacent to the AC coupling capacitor is hollowed out, the grounding holes 4 added nearby can reduce the return path of this part of the plane jump, and the signal returns through the nearby grounding holes 4 when changing layers. Therefore, the packaging structure of the present application for reducing the crosstalk of high-speed signals around the AC coupling capacitor can reduce the crosstalk around the AC coupling capacitor as much as possible.

[0024] like Figure 1 As shown, in one embodiment, the grounding holes 4 are arranged on both sides of the AC coupling capacitor pad and the high-speed signal line via pad 3, and the grounding holes 4 on both sides are symmetrical about the AC coupling capacitor pad. The regular distribution of the grounding holes 4 makes the signal transmission return current of the two AC coupling capacitors consistent and will not affect each other to generate crosstalk. In addition, the regular arrangement of the grounding holes 4 is convenient for the early packaging design drawing.

[0025] like Figure 1As shown, in one embodiment, the grounding hole 4 includes a first grounding hole 401 disposed outside the AC coupling capacitor pad, and a second grounding hole 402 disposed outside the high-speed signal line via pad 3, and the diameter of the second grounding hole 402 is larger than the diameter of the first grounding hole 401. Since the welding surfaces of the AC coupling capacitor pad and the high-speed signal line via pad 3 are not the same, the size of the grounding hole 4 is adjusted according to the corresponding pad, and the volume of the grounding hole 4 can also be reduced.

[0026] In one embodiment, the diameter of the first grounding hole 401 is 16 mil, and the diameter of the second grounding hole 402 is 18 mil.

[0027] like Figure 1 As shown, in one embodiment, the minimum distance between the edge of the AC coupling capacitor pad and the edge of the first grounding hole 401 is Z, 4.5≤Z≤8, in mil. There are four AC coupling capacitor pads, arranged in a 2×2 matrix, and the center spacing between the two high-speed signal line via pads 3 at the same end is X1, 26≤X1≤30, in mil. The disk diameter of the second grounding hole 402 is the same as the outer diameter of the high-speed signal line via pad 3, and the center spacing between the adjacent second grounding holes 402 and the high-speed signal line via pad 3 is X2, X2=X1, that is, the center spacing between the adjacent second grounding holes 402 and the high-speed signal line via pad 3 is consistent with the center spacing between the two high-speed signal line via pads 3 at the same end. The centers of the two high-speed signal line via pads 3 at the same end are on the same straight line L, the center distance of the first grounding hole 401 close to the straight line L is Y1, and the center spacing of the second grounding hole 402 close to the straight line L is Y2, Y1=Y2. The minimum spacing between the edge of the high-speed signal line via pad 3 and the edge of the AC coupling capacitor is K, 8≤K≤12, in mils.

[0028] In one embodiment, the second ground hole 402 and the high-speed signal line via pad 3 are 18 mils, and the drill hole is 8 mils.

[0029] In one embodiment, the AC coupling capacitor pad 2 is suitable for welding of 0201 capacitors, or in other embodiments, the AC coupling capacitor is suitable for welding of 0402 capacitors. That is, the packaging structure for reducing high-speed signal crosstalk around the AC coupling capacitor can be suitable for packaging of 0201 coupling capacitors, or for packaging of 0402 coupling capacitors.

[0030] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the claims attached to the utility model.

[0031] The above is an exemplary description of the utility model patent in conjunction with the accompanying drawings. It is obvious that the implementation of the utility model patent is not limited to the above-mentioned method. As long as various improvements are made by adopting the method concept and technical solution of the utility model patent, or the concept and technical solution of the utility model patent are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor, wherein a circuit board body includes AC coupling capacitor pads arranged in pairs, and a reference plane of the AC coupling capacitor pads is hollowed out on a GND layer adjacent to the AC coupling capacitor pads, characterized in that: Both ends of each pair of the AC coupling capacitor pads are provided with high-speed signal line via pads, and grounding holes are provided around the AC coupling capacitor pads and the high-speed signal line via pads, and the grounding holes are respectively arranged in one-to-one correspondence with the AC coupling capacitor pads and the high-speed signal line via pads.

2. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to claim 1, characterized in that: The grounding holes are arranged on both sides of the AC coupling capacitor pad and the high-speed signal line via pad, and the grounding holes on both sides are symmetrical with respect to the AC coupling capacitor pad.

3. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to claim 2, characterized in that: The grounding hole includes a first grounding hole arranged outside the AC coupling capacitor pad and a second grounding hole arranged outside the high-speed signal line via pad, and the diameter of the second grounding hole is larger than the diameter of the first grounding hole.

4. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to claim 3, characterized in that: The diameter of the first grounding hole is 16 mil, and the diameter of the second grounding hole is 18 mil.

5. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to claim 3, characterized in that: The minimum distance between the edge of the AC coupling capacitor pad and the edge of the first ground hole is Z, 4.5≤Z≤8, and the unit is mil.

6. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to claim 5, characterized in that: There are four AC coupling capacitor pads arranged in a 2×2 matrix, and the center distance between the two high-speed signal line via pads at the same end is X1, 26≤X1≤30, and the unit is mil.

7. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to claim 6, characterized in that: The diameter of the second grounding hole is the same as the outer diameter of the high-speed signal line via pad, and the center distance between adjacent second grounding holes and the high-speed signal line via pad is X2, where X2=X1.

8. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to claim 6, characterized in that: The centers of the two high-speed signal line via pads at the same end are on the same straight line L, the center of the first grounding hole close to the straight line L is Y1 away from the straight line L, and the distance between the center of the second grounding hole close to the straight line L and the straight line L is Y2, Y1=Y2.

9. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to claim 6, characterized in that: The minimum spacing between the edge of the high-speed signal line via pad and the edge of the AC coupling capacitor is K, 8≤K≤12, and the unit is mil.

10. The packaging structure for reducing high-speed signal crosstalk around an AC coupling capacitor according to any one of claims 1 to 9, characterized in that: The AC coupling capacitor pad is suitable for welding a 0201 coupling capacitor or a 0402 coupling capacitor.

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