Differential pair noise suppression structure

Abstract

The present invention relates to a differential pair noise suppression structure. A circuit board includes at least one substrate having opposite first and second surfaces. A pair of plated vias are disposed along a z-axis. The first surface of the substrate is provided with a first metal line, a second metal line, a first plated via opening, and a second plated via opening to form a differential pair circuit structure. A metal ground is provided on the second surface of the substrate, the metal ground having a blank area. From a projection perspective, the metal ground area encompasses both signal lines to eliminate reflection noise caused by a boundary between the blank area and the metal ground so that the differential pair signal lines have a uniform characteristic impedance.

Description

Technical Field

[0001] This invention relates to a noise suppression structure, and more particularly to a noise suppression structure for differential pair signal lines. Background Technology

[0002] In differential signaling, each signal is transmitted using a differential pair. That is, the signal carried by one wire has the same signal level as the signal carried by the other wire, but with opposite polarities. The signal at the receiving end is interpreted as the difference between the two lines that make up the differential pair. If the differential pair signal is interfered with, both lines will experience the same interference simultaneously, but this will not affect the signal difference between the lines. This makes differential signal pairs immune to electrical interference.

[0003] like Figures 1A-1C As shown, US Patent 8,715,006B2 discloses a circuit board having a multi-group differential pair structure. Figure 1A The plan view of the differential pair structure is shown, wherein the substrate 100 has a first surface 101 and a second surface 102. The first surface 101 of the substrate 100 shows a differential pair DP, which has a first plated through-hole PTH1, a second plated through-hole PTH2, a first metal line MT1, and a second metal line MT2. Figure 1B The second surface 102 of the display substrate 100 has a metal ground 11 with a rectangular blank area 12 for a first plated through-hole PTH1 and a second plated through-hole PTH2 to pass through. The blank area 12 does not have metal. Figure 1C Viewed from the second side 102 of the substrate 100, from a projection (perspective) angle, the area of ​​the blank area 12 covers the entire area of ​​the first plated through-hole PTH1, the second plated through-hole PTH2, a portion of the first metal line MT1, and a portion of the second metal line MT2.

[0004] When an electromagnetic wave travels from one medium to another, reflection noise is generated at the boundary B where the two media meet. When the electromagnetic wave encounters boundary B, some energy is transmitted as a signal, and some energy is reflected. For electrical engineers, this effect of the medium boundary is usually described in terms of impedance; that is, boundary B is where the impedance changes. Whenever the impedance in a circuit changes, reflection noise occurs.

[0005] From the perspective of projection, Figure 1C The first metal line MT1 is mostly covered by the area of ​​the ground metal 11, but near the first plated via PTH1, a portion is covered by the area of ​​the blank area 12. Similarly, the second metal line MT2 is mostly covered by the area of ​​the ground metal 11, but near the second plated via PTH2, a portion is covered by the area of ​​the blank area 12. A boundary B is formed between the blank area 12 and the ground metal 11; therefore, reflection noise is generated from boundary B. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, according to the embodiments of the present invention, it is desirable to provide a noise suppression structure for differential pair signal lines, which, from a projection (perspective) perspective, covers the entire metal conductor of the differential pair signal line with the area of ​​the metal ground, so that the entire metal conductor of the differential pair signal line maintains the continuity of characteristic impedance.

[0007] According to an embodiment, the present invention provides a differential pair noise suppression structure, comprising a substrate having a first surface, a second surface opposite to the first surface, a first plated through-hole, and a second plated through-hole, wherein:

[0008] A first metal pad, a second metal pad, a first metal wire, and a second metal wire are disposed on a first surface of a substrate. The first metal pad surrounds the opening of a first plated through-hole, and the second metal pad surrounds the opening of a second plated through-hole. The first metal wire has a first straight region and a first bridging region, and the second metal wire has a second straight region and a second bridging region. The first straight region is parallel to the second straight region. The first bridging region electrically connects the first straight region to the first metal pad, and the second bridging region electrically connects the second straight region to the second metal pad.

[0009] A metal ground is provided on the second side of the substrate. The metal ground has a blank area. From the perspective of projection, the metal ground completely covers the first bridging area and the second bridging area.

[0010] According to one embodiment, in the aforementioned differential pair noise suppression structure of the present invention, from the perspective of projection, the blank area completely covers the entire area of ​​the first metal pad and the second metal pad.

[0011] According to one embodiment, in the aforementioned differential pair noise suppression structure of the present invention, from the perspective of projection, the blank area at least covers a portion of the first metal pad and the second metal pad.

[0012] According to one embodiment, in the aforementioned differential pair noise suppression structure of the present invention, from a projection perspective, the blank area does not cover the first bridging area and the second bridging area.

[0013] According to one embodiment, in the aforementioned differential pair noise suppression structure of the present invention, from a projection perspective, the blank area does not cover the first bridging area and the second bridging area.

[0014] According to one embodiment, in the aforementioned differential pair noise suppression structure of the present invention, the blank area is capsule-shaped and has a groove, disposed between the first metal pad and the second metal pad.

[0015] According to one embodiment, in the aforementioned differential pair noise suppression structure of the present invention, the blank area is a kidney-shaped or crescent-shaped block with a groove disposed between the first metal pad and the second metal pad.

[0016] Compared to existing technologies, this invention extends the metal ground, making the entirety of the metal lines MT1 and MT2 covering the differential pair DP in the projection view, in order to eliminate boundary effects. This ensures that the characteristic impedance of the first metal line MT1 and the second metal line MT2 before they are connected to the corresponding first metal pad MP1 and second metal pad MP2 is continuous, thereby eliminating reflection noise. Attached Figure Description

[0017] Figures 1A-1C This is a schematic diagram of a common circuit board with multiple differential pair structures. Figure 1A Show the planar diagram of the difference pair structure. Figure 1B The structure of the second side 102 of the display substrate 100, Figure 1C This shows a projection (perspective) view as seen from the second surface 102 of the substrate 100.

[0018] Figure 2This is a schematic diagram of the first embodiment of the differential pair noise suppression structure of the present invention.

[0019] Figure 3 This is a schematic diagram of the second embodiment of the differential pair noise suppression structure of the present invention.

[0020] Figure 4 This is a schematic diagram of the third embodiment of the differential pair noise suppression structure of the present invention.

[0021] Figure 5 This is a schematic diagram of the fourth embodiment of the differential pair noise suppression structure of the present invention.

[0022] Wherein: 100 is the substrate; 101 is the first surface; 102 is the second surface; 11 is the metal ground; 22A, 22B, 32A, 32B are blank areas; B is the boundary; BP1 is the first bridging area; BP2 is the second bridging area; MP1 is the first metal pad; MP2 is the second metal pad; MT1 is the first metal line; MT2 is the second metal line; PTH1 is the first plated through-hole; PTH2 is the second plated through-hole; R1, R2 are grooves; SP1 is the first straight line area; SP2 is the second straight line area. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. These embodiments should be understood as illustrative only and not as limiting the scope of protection of the present invention. After reading the description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

[0024] First embodiment.

[0025] Figure 2 This diagram shows a circuit board comprising at least one substrate 100 having a first surface 101 and a second surface 102, the first surface 101 and the second surface 102 being positioned opposite each other. A first plated through-hole PTH1 and a second plated through-hole PTH2 are formed therein, passing through the first surface 101 and the second surface 102. Figure 2 It is a projection view, which is an angle from the second surface 102 of the substrate 100 to the first surface 101 of the substrate 100 to observe the relative position of the circuit.

[0026] On the first surface 101 of the substrate 100, multiple sets of metal lines, including a first metal line MT1 and a second metal line MT2, are formed. A first metal pad MP1 surrounds the opening of a first plated through-hole PTH1, and a second metal pad MP2 surrounds the opening of a second plated through-hole PTH2. The first metal line MT1 has a first straight region SP1 and a first bridging region BP1, and the second metal line MT2 has a second straight region SP2 and a second bridging region BP2. The first straight region SP1 and the second straight region SP2 are arranged parallel to each other. The first bridging region BP1 electrically couples the first straight region SP1 to the first metal pad MP1, and the second bridging region BP2 electrically couples the second straight region SP2 to the second metal pad MP2.

[0027] On the second surface 102 of the substrate 100, a metal ground 11 is formed. The material of the metal ground 11 is typically copper, which provides electrical grounding for the substrate 100 of the circuit board. A blank area 22A is formed within the metal ground 11. From a projection perspective, the area of ​​the blank area 22A completely or almost completely covers the first metal pad MP1 and the second metal pad MP2.

[0028] From a projection perspective, the area of ​​metal ground 11 covers the entire area of ​​the first bridging region BP1 and the second bridging region BP2.

[0029] From the perspective of projection, the area of ​​blank region 22A does not cover any area of ​​metal lines MT1 and MT2; while at the same time, the area of ​​metal ground 11 covers the entire first metal line MT1 and the second metal line MT2. Therefore, the characteristic impedance of the entire first metal line MT1 and the second metal line MT2 can be kept the same throughout the entire line.

[0030] The area of ​​blank region 22A is capsule-shaped and has a groove R1 disposed between the first metal pad MP1 and the second metal pad MP2. From a projection perspective, the area of ​​blank region 22A does not cover the first bridging region BP1 and the second bridging region BP2.

[0031] Second embodiment.

[0032] Figure 3 yes Figure 2 The modified embodiment, from the perspective of projection, Figure 3 The area of ​​the blank region 22B is shifted to the left to ensure that the area of ​​the metal ground 11 completely covers the entire area of ​​the first metal line MT1 and the second metal line MT2. The area of ​​the blank region 22B is shaped like a capsule, with a groove R1 disposed between the first metal pad MP1 and the second metal pad MP2. From the projection angle, the area of ​​the blank region 22B does not cover the first bridging region BP1 and the second bridging region BP2.

[0033] Third embodiment.

[0034] Figure 4 Is with Figure 2 Similar noise suppression structures, the only difference being the area and shape of the blank region 32A. Figure 4 The area of ​​the blank region 32A is kidney-shaped or crescent-shaped, and the groove R2 is disposed between the first metal pad MP1 and the second metal pad MP2. From the projection angle, the area of ​​the blank region 32A does not cover the first bridging region BP1 and the second bridging region BP2.

[0035] Fourth embodiment.

[0036] Figure 5 It is similar to Figure 3 The only difference in the noise suppression structure is the area and shape of the blank region 32B. Relative to... Figure 4 The area and shape of the blank area 32B are shifted entirely to the left to ensure that the area of ​​the metal ground 11 can completely cover the first bridging area BP1 and the second bridging area BP2. From the projection perspective, Figure 5 The blank area 32B, shaped like a kidney or crescent, has a groove R2 and is positioned between the first metal pad MP1 and the second metal pad MP2. From a projection perspective, the area of ​​the blank area 32B does not encompass the first bridging area BP1 and the second bridging area BP2. (Compared to...) Figure 4 The area of ​​the blank region 32A, Figure 5 The area of ​​the blank area 32B is shifted to the left. From the projection angle, this ensures that the area of ​​the blank area 32B does not cover the first bridging area BP1 and the second bridging area BP2. At the same time, it ensures that the area of ​​the metal ground 11 covers the entire first metal line MT1 and the second metal line MT2.

Claims

1. A differential pair noise suppression structure comprising a substrate, characterized by, The substrate has a first surface, a second surface opposite to the first surface, a first plated through-hole, and a second plated through-hole, wherein A first metal pad, a second metal pad, a first metal wire, and a second metal wire are provided on the first surface of the substrate. The first metal pad surrounds the opening of the first plated through hole, and the second metal pad surrounds the opening of the second plated through hole. The first metal wire has a first straight region and a first bridging region, and the second metal wire has a second straight region and a second bridging region. The first straight region is parallel to the second straight region. The first bridging region electrically connects the first straight region to the first metal pad, and the second bridging region electrically connects the second straight region to the second metal pad. A metal ground is provided on the second side of the substrate. The metal ground has a blank area. From the perspective of projection, the metal ground completely covers the first bridging area and the second bridging area.

2. The differential pair noise suppression structure of claim 1, wherein, From the perspective of projection, the blank area completely covers the entire area of ​​the first metal pad and the second metal pad.

3. The differential pair noise suppression structure of claim 1, wherein, From a projection perspective, the blank area at least covers a portion of the first metal pad and the second metal pad.

4. The differential pair noise suppression structure of claim 2, wherein, From a projection perspective, the blank area does not cover the first bridging area or the second bridging area.

5. The differential pair noise suppression structure of claim 3, wherein, From a projection perspective, the blank area does not cover the first bridging area or the second bridging area.

6. The differential pair noise suppression structure of claim 4, wherein, The blank area is capsule-shaped and has a groove, which is disposed between the first metal pad and the second metal pad.

7. The differential pair noise suppression structure of claim 5, wherein, The blank area is capsule-shaped and has a groove, which is disposed between the first metal pad and the second metal pad.

8. The differential pair noise suppression structure of claim 4, wherein, The blank area is kidney-shaped or crescent-shaped and has a groove, which is disposed between the first metal pad and the second metal pad.

9. The differential pair noise suppression structure of claim 5, wherein, The blank area is a kidney-shaped or crescent-shaped block with a groove, located between the first metal pad and the second metal pad.

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