CN220273928U - PCB structure for improving surface layer microstrip line crosstalk - Google Patents

Abstract

The utility model discloses a PCB structure that improves the crosstalk of surface microstrip lines. It includes a surface layer and a reference layer arranged below the surface layer. The surface layer is provided with a surface microstrip line. The surface microstrip line includes a first microstrip line and a reference layer. The second microstrip line, the first microstrip line and the second microstrip line are parallel to each other. The space between the first microstrip line and the second microstrip line forms a reflow area between the projections of the reference layer. The reflow area A hollowed-out partition zone is provided inside to separate the reflow area along the direction of the surface microstrip line. The utility model provides a PCB structure that improves the crosstalk of surface microstrip lines, so that the microstrip line has a cut-off hollowed-out area inside the projection area of the reference layer, so that the return ground of the two parallel lines that constitute the microstrip line has a cut-off space to avoid complete intersection of the electromagnetic fields generated by two parallel traces during the reflow process, thereby improving the signal crosstalk phenomenon in microstrip line transmission and improving signal transmission quality.

Description

A PCB structure that improves surface microstrip line crosstalk

Technical field

The utility model relates to the technical field, and more specifically, to a PCB structure that improves surface microstrip line crosstalk.

Background technique

Microstrip line is a kind of transmission line, which is composed of conductor, medium and ground. Microstrip line is set on the printed circuit board and is used to transmit microwave signals. Microstrip lines can be seen as evolving from double conductors, usually an extension of parallel double lines. A metal conductive plate is placed on the center surface of the parallel double lines. The metal conductive plate is perpendicular to all power lines, maintaining the original electromagnetic field structure. , so that when one of the wires is removed, the electromagnetic field structure of the other wire remains unchanged, so the remaining wires and metal conductive plates form a microstrip line.

In layman's terms, microstrip lines can be considered as parallel traces set on the surface of the PCB, that is, surface traces. Since the medium in contact with the surface traces above is air, and the medium in contact with the bottom is the board, there is a difference in the dielectric constant of the air and the board. Normally, the relative dielectric constant of air is 1, and the relative dielectric constant of the board is 4. , in this case, there is a difference in the transmission speed of the differential mode and common mode signals of the microstrip line. If the spacing between the two parallel lines that constitute the microstrip line is small, the crosstalk phenomenon of the signals transmitted by the microstrip line will be relatively small. Seriously, it affects the quality of signal transmission.

Contents of the invention

In order to improve the problem that the spacing between two parallel lines of microstrip lines is small and affects the signal transmission quality, the utility model provides a PCB structure that improves the crosstalk of surface microstrip lines.

The technical solution of the present utility model is as follows:

A PCB structure that improves crosstalk of surface microstrip lines, including a surface layer and a reference layer provided below the surface layer. The surface layer is provided with a surface microstrip line, and the surface microstrip line includes a first microstrip line and a second microstrip line. , the first microstrip line and the second microstrip line are parallel to each other, the space between the first microstrip line and the second microstrip line forms a reflow area between the projections of the reference layer, and a hollowed-out partition is provided in the reflow area strip, so that the reflow area is separated along the direction of the surface microstrip line.

Since the surface microstrip line needs to reflow through the reference layer, during the reflow process of the first microstrip line and the second microstrip line, the first microstrip line and the second microstrip line generate their own reflow electromagnetic fields. The two reflow electromagnetic fields are not restricted in the reference layer, so the two can completely intersect, resulting in serious crosstalk in the transmission signals of the surface microstrip line. Therefore, in the present utility model, in the reference layer where the surface microstrip line realizes reflow, the reflow area shared by the first microstrip line and the second microstrip line, that is, the first microstrip line and the second microstrip line are In the area between the projections of the reference layer, along the wiring path of the first surface layer microstrip line, hollow out to form a strip-shaped hollow partition zone, thereby blocking the first microstrip line and the second microstrip line. The intersection between the backflow electromagnetic fields of the first microstrip line and the second microstrip line will be relatively small, which can effectively improve the crosstalk phenomenon of the transmission signal.

In the above-mentioned PCB structure for improving crosstalk of surface microstrip lines, the distance between the first microstrip line and the second microstrip line is less than or equal to 30 mils.

In the above-mentioned PCB structure that improves the crosstalk of surface microstrip lines, the distance between the projection line of the first microstrip line or the second microstrip line on the reference layer and the hollowed-out partition zone is at least the distance between the surface layer and the reference layer. three times the distance.

In order to ensure that the reference processing of the surface microstrip line is normal, according to the radiation theory of the electromagnetic field, an area with a width three times the distance between the surface layer and the reference layer is reserved in the reflow area, which can wrap 97% of the energy and basically not It affects the signal quality transmitted by the surface microstrip line.

According to the above solution, the beneficial effect of the present utility model is that the present utility model provides a PCB structure that improves the crosstalk of surface microstrip lines. The surface layer below the surface layer of the microstrip line is used as a reference ground plane for the microstrip line. The reference layer is hollowed out, so that the microstrip line has a cut-off hollowed-out area inside the projection area of the reference layer, so that there is a cut-off space in the return ground of the two parallel traces that constitute the microstrip line, preventing the two parallel traces from There is a complete intersection between the electromagnetic fields generated during the reflow process, thereby improving the signal crosstalk phenomenon in microstrip line transmission and improving the signal transmission quality.

Description of drawings

In order to explain the technical solutions in the embodiments of the present invention more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the purpose of the present utility model. For some embodiments of the new type, those of ordinary skill in the art can also obtain other drawings based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of the utility model.

Among them, each figure in the figure is marked with:

1. The first microstrip line; 2. The second microstrip line; 3. Reflow area; 4. Hollowed partition strip; 5. PCB board; 6. Surface layer; 7. Reference layer.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model more clear, the present utility model will be further described in detail below with reference to the drawings and examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

A PCB structure that improves the crosstalk of surface microstrip lines. As shown in Figure 1, the PCB board 5 includes a surface layer 6 and a reference layer 7 provided below the surface layer 6. The surface layer 6 is provided with surface microstrip lines. The reference layer Layer 7 is the layer where the surface microstrip line reflow is located, usually the reference ground plane layer.

The surface microstrip line includes a first microstrip line 1 and a second microstrip line 2. The first microstrip line 1 and the second microstrip line 2 are parallel to each other, forming a parallel double line structure, as shown in Figure 1. A microstrip line 1 and a second microstrip line 2 form a strip structure.

In this embodiment, the distance between the first microstrip line 1 and the second microwire is 30 mils. Under this distance, the crosstalk phenomenon caused by the signals transmitted by the surface microstrip line is more serious, affecting the signal transmission quality.

The projection lines of the first microstrip line 1 and the second microstrip line 2 in the reference layer 7 are set as the first projection line and the second projection line. A reflow area 3 is formed between the first projection line and the second projection line. . The reflow region 3 is the common reflow ground for the first microstrip line 1 and the second microstrip line 2. The reflow electromagnetic fields formed by the first microstrip line 1 and the second microstrip line 2 completely intersect in the reflow region 3.

A hollow partition strip 4 is provided in the reflow area 3 so that the reflow area 3 is separated along the direction of the surface microstrip line. As shown in Figure 1, the hollowed-out partition strips 4 are distributed in a strip shape along the path of the surface microstrip lines, so that there is a partition space in the return flow area 3, and the first projection line and the second projection line are respectively located in the hollowed-out partition strips 4 On both sides, the spaces where the two are located are separated by hollowed-out partition strips 4. In this way, by hollowing out the partition strip 4 , there is a hollow space for the common reflow of the first microstrip line 1 and the second microstrip line 2 , and the first microstrip line 1 and the second microstrip line 2 are in the reference layer 7 The backflow is interrupted by the hollow space, so that the intersection of the backflow between the first microstrip line 1 and the second microstrip line 2 is reduced, thereby improving the crosstalk phenomenon of the surface microstrip line transmission signal.

In order to ensure that the reference processing of the surface microstrip line is normal, according to the radiation theory of the electromagnetic field, an area with a width three times the distance between the surface layer 6 and the reference layer 7 is reserved in the reflow area 3, that is, between the surface layer 6 and the reference layer 7 The distance between the first projection line or the second projection line and the reflow area 3 is at least 3R. This strip-shaped area with a width of at least 3R in the reflow area 3 can wrap 97% of the energy and will basically not affect the signal quality transmitted by the surface microstrip line.

The above descriptions are only preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present utility model shall be included in the present utility model. Within the protection scope of utility model.

Claims (3)

1. The PCB structure is characterized by comprising a surface layer and a reference layer arranged below the surface layer, wherein the surface layer is provided with the surface layer microstrip line, the surface layer microstrip line comprises a first microstrip line and a second microstrip line, the first microstrip line and the second microstrip line are parallel to each other, a backflow area is formed in a space between projections of the reference layer, and a hollowed partition belt is arranged in the backflow area, so that the backflow area is partitioned along the direction of the surface layer microstrip line.

2. The PCB structure of claim 1, wherein a pitch between the first microstrip line and the second microstrip line is 30 mils or less.

3. The PCB structure of claim 1, wherein a distance between a projection line of the reference layer and the hollowed-out strip of the first microstrip line or the second microstrip line is at least three times a distance between the surface layer and the reference layer.