Signal via hole positioning method for optimizing via hole crosstalk between signals

Abstract

The invention relates to a signal via hole positioning method for optimizing via hole crosstalk between signals. The method comprises the following steps: step 1, establishing a preliminary model; 2, disassembling the model and redefining the model; step 3, parameterization setting of the model; step 4, scanning variables and simulation results; and step 5, positioning the position of the second pair of differential signal via hole structures according to the simulation result. According to the invention, the problem of lack of enough layout space in the direction of conventionally pulling the distance between the via holes is solved; the method comprises the following steps: establishing a preliminary model, accurately inserting and aligning two pairs of differential signal via hole structures, fixing one pair of differential signal via hole structures, opening up a new direction to move the second pair of differential signal via hole structures, and establishing a variable and scanning the variable. The finally obtained optimal interval result is not the interval that the two pairs of differential signal via holes are pulled open to the maximum, but is located at a certain distance in the middle, the space problem of design engineers is solved, and a better crosstalk design scheme is obtained.

Description

Technical Field

[0001] The present invention relates to the field of circuit design, and in particular to a signal via positioning method for optimizing via crosstalk between signals. Background Art

[0002] In the field of circuit board design, a pair of differential signal vias is two paired vias used to transmit differential signals. Both vias run from the top layer of the PCB to the bottom layer or a certain inner layer, and the two vias are located in an anti-pad area. The function of the anti-pad is to reduce unnecessary capacitive coupling between the via and the adjacent plane layer. On the top layer, the two traces of the differential signal are connected to the corresponding via pads respectively, so that the signal can reach the bottom layer or inner layer through the via, and finally lead out from the lower layer; whether on the top layer or the lower layer, the two differential signal lines generally maintain a fixed spacing throughout the entire process.

[0003] If the distance between two pairs of differential signal vias is too close, the electromagnetic radiation fields between them will overlap and interfere with each other, resulting in obvious signal crosstalk. The general practice is to increase the distance between the two pairs of differential signal vias in the direction of the vertical distance between the edges of the two anti-pad areas (defined as the X direction) to increase the physical spacing, thereby weakening the strength of the electromagnetic coupling between them. The greater the distance, the better the effect of reducing crosstalk. The optimization of high-speed differential signal vias can be performed through 3D simulation software. Only a distance parameter needs to be entered in the software to change the distance between the two pairs of differential signal vias in the X direction.

[0004] However, in the circuit design layout of a certain project, it was found that there was not enough space in the X direction of the two pairs of differential signal vias to increase the spacing between the two pairs of differential signal vias. In addition, it was found that there was sufficient layout space in another direction perpendicular to the X direction (defined as the Y direction). So, can we break the conventional thinking and solve the problem of the two pairs of differential signal vias being too close in the Y direction? Summary of the invention

[0005] In order to overcome the problem in the existing circuit layout that two pairs of differential signal vias are too close to each other, there is obvious signal crosstalk, and there is insufficient layout space in the direction of conventionally increasing the via spacing, the present invention provides a signal via positioning method for optimizing the via crosstalk between signals.

[0006] The technical solution of the present invention is as follows:

[0007] A signal via positioning method for optimizing via crosstalk between signals, comprising the following steps:

[0008] Step 1: Establish a preliminary model;

[0009] Inserting a first pair of differential signal via structures and a second pair of differential signal via structures, and aligning the two pairs of differential signal via structures;

[0010] Step 2: Disassemble the model and redefine the model;

[0011] Define fixed differential signal via structures and mobile differential signal via structures;

[0012] Step 3: Model parameterization setting;

[0013] Define the moving direction and displacement of the mobile differential signal via structure, and set the displacement as a variable;

[0014] Step 4, scan variables and simulate results;

[0015] The software iterates the variable value within the set range and simulates to obtain multiple sets of crosstalk results;

[0016] Step 5: Locate and move the differential signal via structure according to the simulation results.

[0017] As a preferred technical solution of the present invention, the step 1 comprises the following steps:

[0018] Step 101, open the simulation software and create a blank PCB project file;

[0019] Step 102, retrieve a pair of differential signal via structures from the component library, and place them in the initial setting area of ​​the PCB model;

[0020] Step 103, retrieve another pair of differential signal via structures from the component library, place them on one side of the first pair of differential signal via structures, and align them with the first pair of differential signal via structures;

[0021] Step 104 , fill in various parameters of the differential signal via structure.

[0022] Furthermore, the differential signal via structure includes two pairs of signal vias, two pairs of return ground vias and an anti-pad area.

[0023] Furthermore, the parameters in step 104 include via aperture, routing path and line width, fan-out routing layer position, and anti-pad area size.

[0024] As a preferred technical solution of the present invention, the step 2 specifically includes the following steps:

[0025] Step 201, setting a first pair of differential signal via structures as fixed objects;

[0026] Step 202, splitting the second pair of differential signal via structures into a signal via pair, a return ground via pair, and an anti-pad area;

[0027] Step 203: define the signal via pair and the reflow ground via pair as a three-dimensional structure and set them as the first moving part that moves synchronously; define the anti-pad area as a two-dimensional surface structure and set it as the second moving part.

[0028] As a preferred technical solution of the present invention, the step 3 specifically includes the following steps:

[0029] Step 301, establishing a coordinate system;

[0030] The center of one of the signal vias of the first pair of differential signal via structures is taken as the origin, the direction from the origin to the center of the other signal via in the same pair is taken as the Y axis, and the direction from the origin to the second pair of differential signal via structures is taken as the X axis;

[0031] Step 302, defining the moving direction;

[0032] Define the moving direction of the first moving part and the second moving part of the second pair of differential signal via structures as the positive direction of the Y axis;

[0033] Step 303: setting variable parameters;

[0034] The displacements of the first moving part and the second moving part are set to be equal and represented by a displacement variable parameter S; and the range and step value of the displacement variable parameter S are set.

[0035] Further, the range of the displacement variable parameter S is 0 to 100 mil.

[0036] Furthermore, the step value of the displacement variable parameter S is 10 mil, 8 mil or 5 mil.

[0037] Furthermore, the step 4 specifically includes the following steps:

[0038] Step 401, start the scanning process;

[0039] According to the displacement variable parameter S set in step 3, starting from the initial value, the step value is gradually increased. Each time the value of the displacement variable parameter S is adjusted, the first moving part and the second moving part will synchronously move a corresponding distance in the positive direction of the Y axis;

[0040] Step 402, calculating the via-to-via crosstalk result;

[0041] After each displacement change of the second pair of differential signal via structures, the software automatically calculates the crosstalk results between the two pairs of differential signal vias;

[0042] Step 403, drawing and displaying a crosstalk curve comparison diagram;

[0043] Each time the crosstalk calculation under the displacement parameters is completed, the result is automatically recorded, and the crosstalk curves of all the results are automatically drawn in the same chart to obtain a comparison chart of multiple groups of crosstalk curves.

[0044] As a preferred technical solution of the present invention, the specific steps of step 5 are:

[0045] An optimal result is screened out from multiple groups of crosstalk results, and a movement displacement corresponding to the optimal result is obtained, and the position of the moved second pair of differential signal via structures is determined based on the displacement.

[0046] The present invention according to the above scheme has the following beneficial effects:

[0047] The present invention provides a new solution for optimizing crosstalk between differential signal vias, which solves the problem of lack of sufficient layout space in the direction of conventionally widening the via spacing. In the preliminary model establishment stage, two pairs of differential signal via structures are accurately inserted and aligned, one pair of the differential signal via structures is fixed, and a new direction is opened to move the second pair of differential signal via structures. By establishing variables and scanning variables, the spacing between the two pairs of differential signal vias is widened and the optimal crosstalk value between the vias is sought. The optimal spacing result finally obtained is not that the two pairs of differential signal vias are widened to the maximum spacing, but that they are at a certain distance in the middle. This result breaks through the inherent thinking and eliminates the disadvantage of occupying a large amount of wiring space caused by widening the maximum spacing. It not only solves the space problem of design engineers, but also obtains a better crosstalk design solution, which is worthy of popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a flow chart of the method of the present invention;

[0049] Figure 2 It is a structural schematic diagram of the present invention;

[0050] Figure 3 A schematic diagram of increasing the spacing between two pairs of differential signal via holes according to the present invention;

[0051] Figure 4 It is a comparison chart of multiple groups of crosstalk curves;

[0052] Figure 5 for Figure 4 Comparison of the crosstalk curves in the middle part.

[0053] In the figure,

[0054] 100. a first pair of differential signal via structures;

[0055] 200, a second pair of differential signal via structures;

[0056] 1. Signal via; 2. Return ground via; 3. Anti-pad area. DETAILED DESCRIPTION

[0057] In order to better understand the purpose, technical scheme and technical effect of the present invention, the present invention is further explained in conjunction with the accompanying drawings and embodiments. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, it is stated that the embodiments described below are only used to explain the present invention and are not used to limit the present invention.

[0058] It should be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may also be a central element, and when an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time.

[0059] The indicated orientation or position relationship is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the application product is usually placed when in use, or the orientation or position relationship commonly understood by those skilled in the art, or the orientation or position relationship in which the application product is usually placed when in use. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present application. The terms "first" and "second" 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.

[0060] like Figures 1 to 3 As shown, a signal via positioning method for optimizing via crosstalk between signals includes the following steps:

[0061] Step 1: Establish a preliminary model;

[0062] Inserting the first pair of differential signal via structures 100 and the second pair of differential signal via structures 200, and aligning the two pairs of differential signal via structures;

[0063] Step 1 specifically includes the following steps:

[0064] Step 101, open the 3D circuit design simulation software and create a blank PCB project file;

[0065] Step 102, retrieve a pair of standard structures of differential signal vias from a component library, and place them in an initial setting area of ​​a PCB model;

[0066] Step 103, retrieve another pair of standard structures of differential signal vias from the component library, place them on one side of the first pair of differential signal via structures, and align the left signal vias and right signal vias of the two pairs of differential signal via structures, that is, the left signal vias of the first pair of differential signal via structures are aligned with the left signal vias of the second pair of differential signal via structures, and the right signal vias of the first pair of differential signal via structures are aligned with the right signal vias of the second pair of differential signal via structures;

[0067] Step 104 , fill in various parameters of the differential signal via structure, including via aperture, routing path and line width, fan-out routing layer position, and anti-pad area size.

[0068] In this embodiment, the differential signal via structure includes two pairs of signal vias 1, two pairs of return ground vias 2, that is, a signal via pair and a return ground via pair, and also includes an anti-pad area 3. Each signal via runs from the top board to the bottom board or the inner board, and is connected to a surface signal trace on the top board, and is connected to a fan-out signal trace on the bottom board or the inner board. The two return ground vias are respectively arranged on both sides of the signal via pair, and the signal via pair is located in the anti-pad area, and the return ground via pair is located outside the anti-pad area.

[0069] Step 2: Disassemble the model and redefine the model;

[0070] Define fixed differential signal via structures and mobile differential signal via structures.

[0071] Step 2 specifically includes the following steps:

[0072] Step 201, setting a first pair of differential signal via structures as fixed objects;

[0073] Step 202, splitting the second pair of differential signal via structures into a signal via pair, a return ground via pair, and an anti-pad area;

[0074] Step 203: define the signal via pair and the reflow ground via pair as a three-dimensional structure and set them as the first moving part that moves synchronously; define the anti-pad area as a two-dimensional surface structure and set it as the second moving part.

[0075] The signal via pair and the return ground via pair are three-dimensional in physical dimension and have clear three-dimensional size, so they are set as three-dimensional structure. In addition, the signal via pair and the return ground via pair are interdependent in electrical function. Signal transmission and return flow cooperate with each other. The two are set as the first moving part that moves synchronously, and the computing resources are efficiently integrated. In the subsequent movement, the continuity of signal transmission and return flow is guaranteed to avoid electrical performance fluctuations affecting the simulation results and thus affecting the decision. The key factors of the anti-pad area are concentrated in the two-dimensional level, such as the area and shape properties. Following its planar characteristics, a simplified equivalent model is created. When the software processes the movement operation of the second moving part, there is no need for complex three-dimensional space calculations, and the response speed is greatly accelerated.

[0076] Step 3: Model parameterization setting;

[0077] The moving direction and displacement of the first moving part and the second moving part of the mobile differential signal via structure are defined, and the displacement is set as a variable.

[0078] Step 3 specifically includes the following steps:

[0079] Step 301, establishing a coordinate system;

[0080] The center of one of the signal vias of the first pair of differential signal via structures is taken as the origin, the direction from the origin to the center of the other signal via in the same pair is taken as the Y axis, and the direction from the origin to the second pair of differential signal via structures is taken as the X axis;

[0081] Step 302, defining the moving direction;

[0082] Define the moving directions of the first moving part and the second moving part as the positive direction of the Y axis;

[0083] Step 303: setting variable parameters;

[0084] The displacements of the first moving part and the second moving part are set to be equal and represented by a displacement variable parameter S; the range of the displacement variable parameter S is set to be 0 to 100 mil, and the step value of the displacement parameter is 10 mil, 8 mil or 5 mil.

[0085] Step 4, scan variables and simulate results;

[0086] The software iterates the variable value within the set range and simulates multiple sets of crosstalk results. Before starting the variable scan, the software automatically initializes the environment of the model with the current set parameters, and builds a virtual circuit operation scenario based on the established PCB material properties, the preset values ​​of the surrounding electromagnetic environment, and the electrical rules set in the early stage.

[0087] Step 4 specifically includes the following steps:

[0088] Step 401, start the scanning process;

[0089] Start the software variable scanning program, and gradually increase the displacement variable parameter S set in step 3 from the initial value according to the step value; each time the displacement variable parameter S is adjusted, the first moving part and the second moving part will synchronously move the corresponding distance in the positive direction of the Y axis;

[0090] Step 402, calculating the via-to-via crosstalk result;

[0091] After each displacement change of the second pair of differential signal via structures, the software performs an electromagnetic characteristic calculation. Specifically, it focuses on the electromagnetic coupling relationship between the two pairs of differential signal vias, and accurately calculates the specific values ​​of capacitive coupling and inductive coupling in the current layout based on electromagnetic principles such as Maxwell's equations. The calculation of capacitive coupling involves many factors such as via spacing, anti-pad area, and dielectric constant of surrounding media. Based on the electromagnetic coupling data, the crosstalk results between the first pair of differential signal via structures and the second pair of differential signal via structures are further derived and calculated.

[0092] Step 403, drawing and displaying a crosstalk curve comparison diagram;

[0093] Each time a crosstalk calculation under displacement parameters is completed, the software immediately records the results, including the value of the displacement variable parameter S, the corresponding crosstalk value, and key information such as the associated electromagnetic coupling parameters; and automatically draws the crosstalk curves of all results in the same chart to obtain a comparison chart of multiple groups of crosstalk curves.

[0094] Step 5: Locate and move the differential signal via structure according to the simulation results;

[0095] An optimal result is screened out from multiple groups of crosstalk results, and a displacement corresponding to the optimal result is obtained, and the position of the second pair of differential signal via structures is determined based on the displacement.

[0096] In a specific embodiment, the displacement variable parameter S has a value range of (0, 100 mil), and the scanning step value is 10 mil. For a comparison diagram of multiple groups of crosstalk curves obtained in step 4, please refer to Figure 4 For ease of observation, Figure 4 The other curves in are hidden, and the curve a with the best result and the curve b with the largest gap are retained. Please refer to Figure 5As can be seen from the figure, the best crosstalk result is not the result when the displacement variable parameter S is 100mil (-48.29dB), but the result when the displacement variable parameter S is equal to 40mil (-51.75dB). That is to say, the spacing between the two pairs of differential signal vias is increased in the Y-axis direction (horizontal direction in the figure), which is different from the conventional method of increasing the spacing between the two pairs of differential signal vias in the X-axis direction. It is not the default "the greater the distance, the better the effect of reducing crosstalk". This solution breaks through the inherent thinking and obtains a new crosstalk theory.

[0097] In summary, the present invention obtains the best crosstalk value between vias by establishing variables and scanning variables, seeks a new solution, and can break through conventional cognition. The best result is not to pull the two pairs of differential signal vias to the maximum spacing, but to avoid the disadvantage of occupying a large amount of wiring space when the maximum spacing is pulled. It can be seen that the scanning simulation method of different positions between vias established by the present invention can break through the inherent thinking and understand the new crosstalk theory. At the same time, in the case of an intermediate distance, a better crosstalk design scheme is obtained than pulling a larger distance. It not only solves the space problem of the design engineer, but also obtains a better crosstalk design scheme. At the same time, it can make up for the shortcomings of its own inherent theory, and is worthy of promotion.

[0098] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A signal via positioning method for optimizing signal via crosstalk, characterized in that: The following steps are involved: Step 1: Establish a preliminary model; Inserting a first pair of differential signal via structures and a second pair of differential signal via structures, and aligning the two pairs of differential signal via structures; Step 2: Disassemble the model and redefine the model; Define fixed differential signal via structures and mobile differential signal via structures; Step 3: Model parameterization setting; Define the moving direction and displacement of the mobile differential signal via structure, and set the displacement as a variable; Step 4, scan variables and simulate results; The software iterates the variable value within the set range and simulates to obtain multiple sets of crosstalk results; Step 5: Locate and move the differential signal via structure according to the simulation results.

2. The signal via positioning method for optimizing signal via crosstalk according to claim 1, characterized in that: The step 1 comprises the following steps: Step 101, open the simulation software and create a blank PCB project file; Step 102, retrieve a pair of differential signal via structures from the component library, and place them in the initial setting area of ​​the PCB model; Step 103, retrieve another pair of differential signal via structures from the component library, place them on one side of the first pair of differential signal via structures, and align them with the first pair of differential signal via structures; Step 104 , fill in various parameters of the differential signal via structure.

3. The signal via positioning method for optimizing signal via crosstalk according to claim 2, characterized in that: The differential signal via structure includes two pairs of signal vias, two pairs of return ground vias and an anti-pad area.

4. The signal via positioning method for optimizing signal via crosstalk according to claim 2, characterized in that: The parameters in step 104 include via aperture, routing path and line width, fan-out routing layer position, and anti-pad area size.

5. The signal via positioning method for optimizing signal via crosstalk according to claim 1, characterized in that: The step 2 specifically includes the following steps: Step 201, setting a first pair of differential signal via structures as fixed objects; Step 202, splitting the second pair of differential signal via structures into a signal via pair, a return ground via pair, and an anti-pad area; Step 203: define the signal via pair and the reflow ground via pair as a three-dimensional structure and set them as the first moving part that moves synchronously; define the anti-pad area as a two-dimensional surface structure and set it as the second moving part.

6. The signal via positioning method for optimizing signal via crosstalk according to claim 1, characterized in that: The step 3 specifically includes the following steps: Step 301, establishing a coordinate system; The center of one of the signal vias of the first pair of differential signal via structures is taken as the origin, the direction from the origin to the center of the other signal via in the same pair is taken as the Y axis, and the direction from the origin to the second pair of differential signal via structures is taken as the X axis; Step 302, defining the moving direction; Define the moving direction of the first moving part and the second moving part of the second pair of differential signal via structures as the positive direction of the Y axis; Step 303: setting variable parameters; The displacements of the first moving part and the second moving part are set to be equal and represented by a displacement variable parameter S; and the range and step value of the displacement variable parameter S are set.

7. The signal via positioning method for optimizing signal via crosstalk according to claim 6, characterized in that: The range of the displacement variable parameter S is 0 to 100 mil.

8. The signal via positioning method for optimizing signal via crosstalk according to claim 6, characterized in that: The step value of the displacement variable parameter S is 10mil, 8mil or 5mil.

9. The signal via positioning method for optimizing signal via crosstalk according to claim 6, characterized in that: The step 4 specifically comprises the following steps: Step 401, start the scanning process; According to the displacement variable parameter S set in step 3, starting from the initial value, the step value is gradually increased. Each time the value of the displacement variable parameter S is adjusted, the first moving part and the second moving part will synchronously move a corresponding distance in the positive direction of the Y axis; Step 402, calculating the via-to-via crosstalk result; After each displacement change of the second pair of differential signal via structures, the software automatically calculates the crosstalk results between the two pairs of differential signal vias; Step 403, drawing and displaying a crosstalk curve comparison diagram; Each time the crosstalk calculation under the displacement parameters is completed, the result is automatically recorded, and the crosstalk curves of all the results are automatically drawn in the same chart to obtain a comparison chart of multiple groups of crosstalk curves.

10. The signal via positioning method for optimizing signal via crosstalk according to claim 1, characterized in that: The specific steps of step 5 are: An optimal result is screened out from multiple groups of crosstalk results, and a movement displacement corresponding to the optimal result is obtained, and the position of the moved second pair of differential signal via structures is determined based on the displacement.

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