A 2D transmission line modeling method based on routing pattern

Abstract

The present invention relates to the technical field of transmission line modeling, and discloses a 2D transmission line modeling method based on routing pattern. The key points of the technical solution are S1: importing process stacking; S2: specifying signals and reference layers in the process stacking; S3: setting signal layer routing pattern parameters; S4: completing 2D transmission line modeling according to signal lines and reference layers. The method has the advantages of being able to reduce the amount of calculation without sacrificing accuracy, being suitable for preliminary design and optimization, and helping engineers optimize routing layout and material selection in the design stage through simulation results, thereby improving the overall performance of the circuit, and achieving the advantage of flexible construction of 2D transmission line templates.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission line modeling, and more specifically, to a 2D transmission line modeling method based on routing pattern. Background Art

[0002] The traditional 2D transmission line modeling approach requires strict distinction between template types. Transmission line templates are generally divided into several types, such as microstrip lines, strip lines, and coplanar waveguides. The line width, line length, line spacing and other parameters required to construct the template are specified according to each template type.

[0003] At present, the general practice of 2D transmission line modeling is to customize the construction of templates such as single microstrip line, differential microstrip line, single stripline, differential microstrip line, etc. This approach is single and inflexible and cannot build complex models.

[0004] Therefore, the present invention provides a 2D transmission line modeling method based on routing pattern, which improves the above technical problems. Summary of the invention

[0005] The disclosed embodiments aim to address the deficiencies of the prior art and provide a 2D transmission line modeling method based on routing patterns. The present invention completes 2D transmission line modeling based on signal lines and reference layers, and has the ability to reduce the amount of calculation without sacrificing accuracy, and is suitable for preliminary design and optimization. The simulation results help engineers optimize routing layout and material selection in the design stage, thereby improving the overall performance of the circuit, and achieving the advantage of flexible construction of 2D transmission line templates.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: A 2D transmission line modeling method based on routing pattern, comprising the following steps: S1: importing process stacking; S2: Specify signal and reference layers in the process stack; S3: Set the signal layer routing pattern parameters; S4: Complete 2D transmission line modeling based on signal lines and reference layers.

[0007] As a preferred technical solution of the present invention, the process stack includes: the type, thickness and electrical characteristics of each layer of material.

[0008] As a preferred technical solution of the present invention, the reference layer is usually used to provide a reference potential for the signal to reduce electromagnetic interference; the signal layer is used to carry the transmitted signal; and the reference layer is used to provide a return path for the signal.

[0009] As a preferred technical solution of the present invention, the signal layer is composed of a signal layer L1 and a signal layer L3; the reference layer is composed of a reference layer L2 and a reference layer L4; The signal layer L1 is used to transmit a relatively low-speed control signal or clock signal. The signal does not require particularly high frequency control, but still needs to refer to the ground layer L2 to reduce interference and provide a return path for the signal. The reference layer L2 serves as the ground plane of the L1 layer, providing a stable return path, ensuring that the single-ended signal of the L1 layer has a clear reference potential, and reducing ground loop noise and electromagnetic interference; The signal layer L3 is used to transmit high-speed differential signals; the differential signal lines are arranged in pairs, and the impedance of the signal path is controlled by the distance between the L3 layer and the L4 layer and the characteristics of the dielectric layer; The differential signal line of the signal layer L3 works together with the power reference layer of the reference layer L4 to ensure that the signal has a good return path and stable impedance; The reference layer L4 is used as a power layer to provide a reference potential for the high-speed differential signal of L3; When the differential signal is transmitted, the reference of the signal can usually be either a ground layer or a power layer.

[0010] As a preferred technical solution of the present invention, the signal layer routing Pattern parameters include a single signal line and a differential signal line; the routing Pattern is a wiring form of the signal routing.

[0011] As a preferred technical solution of the present invention, the thickness of the dielectric material between the signal layer and the reference layer, as well as the thickness of the signal layer and the reference layer are extracted.

[0012] As a preferred technical solution of the present invention, key parameters of each routing line in the signal layer are extracted; the key parameters include: line width, line spacing, routing direction and whether there is a differential pair.

[0013] As a preferred technical solution of the present invention, the wiring form of each signal line is determined, and the wiring form includes: SSS (single line, single ground) mode and SGSG (single line, single ground, single line, single ground) mode; Calculate the arrangement position of the traces based on parameters such as trace width and spacing.

[0014] As a preferred technical solution of the present invention, the calculation process of the arrangement position is: the starting position of the first signal line can be set to X = 0, the position of the second ground line is on the right side of the first signal line, with a spacing of 0.15 mm, so the center position of the ground line is X = 0.2 + 0.15 = 0.35 mm, the position of the second signal line is on the right side of the ground line, with a distance of 0.15 mm, so the center position of the signal line is X = 0.35 + 0.2 + 0.15 = 0.7 mm, and continuing this arrangement mode, the position of the next ground line is X = 0.7 + 0.2 + 0.15 = 1.05 mm.

[0015] As a preferred technical solution of the present invention, the process of completing 2D transmission line modeling according to the signal line and the reference layer is: taking the middle point of the routing line in the first signal layer as the x-axis zero point of the entire transmission line model, using this as a reference to determine the relative positions of other routing lines, and selecting the middle point of the first signal line as the x-axis zero point as the position reference of other signal lines and reference layers in the model; Determine the position of subsequent signal layers relative to the first signal layer; calculate the relative position of other signal lines on the x-axis based on the position of the first signal line; Use the width, x-direction position, and layer height information of the trace to draw a graph of each trace on the xz plane; construct the geometric shape of each signal line on the xz plane based on the x-axis coordinates of each layer of signal lines and the height information of the stack; According to the position and material thickness information of the reference layer, the geometry of the reference layer on the xz plane is constructed. The reference layer is usually located above and below the signal layer and is responsible for providing a stable current return path. According to the layer height, thickness and other parameters of the reference layer, its geometry on the xz plane is constructed.

[0016] In summary, the present invention has the following beneficial effects: through accurate modeling, engineers can obtain results that are closer to the actual circuit. This helps to predict problems that may occur in the transmission line during signal transmission, such as impedance mismatch, signal reflection and crosstalk. 2D modeling is simpler than 3D modeling, and can reduce the amount of calculation without sacrificing accuracy. It is suitable for preliminary design and optimization. The results obtained through simulation can help engineers optimize the routing layout and material selection in the design stage, thereby improving the overall performance of the circuit and realizing the flexible construction of 2D transmission line templates. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a 2D transmission line modeling method based on a routing pattern provided by an embodiment of the present invention; Figure 2 Flowchart for modeling a 2D transmission line for an embodiment of the invention. DETAILED DESCRIPTION

[0018] The present application is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present application. These all belong to the protection scope of the present application.

[0019] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0020] It should be noted that, if there is no conflict, the various features in the embodiments of the present application can be combined with each other, all within the scope of protection of the present application. In addition, although the functional module division is performed in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a sequence different from the module division in the device or the flow chart. In addition, the words "first", "second", "third", etc. used herein do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0021] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

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

[0023] Please refer to Figure 1 , Figure 1 The 2D transmission line modeling method based on the routing pattern described in the embodiment of the present disclosure is shown. The overall process mainly includes the following 4 steps: S1: import process stack; S2: Specify signal and reference layers in the process stack; S3: Set the signal layer routing pattern parameters; S4: Complete 2D transmission line modeling based on signal lines and reference layers.

[0024] In this embodiment, the stacking information of the actual circuit board (PCB) or chip process is obtained and imported, including the type, thickness and electrical characteristics (such as dielectric constant, loss tangent, etc.) of each layer of material. For example, the stacking structure of the PCB may include information such as the signal layer, the dielectric layer, and the reference layer. The signal layer uses copper foil material, and the dielectric layer uses FR4 material with a dielectric constant of 4.3 and a thickness of 0.2 mm. Importing the process stack is the basis of the entire modeling process, involving information such as material selection, thickness, and electrical characteristics of the signal layer and the reference layer. These parameters usually come from the process specifications or chip design specifications of the PCB manufacturer. The material of each layer in the imported stacking information has different dielectric constants, thicknesses, and other parameters. For example, the signal layer is usually copper, and the dielectric layer is FR4. The dielectric constant and thickness determine the signal propagation speed and loss; Example: Signal layer 1 (L1): Material: copper foil, Thickness: 0.035 mm (35 μm), Electrical properties: ideal conductive material (usually assumed to be PEC); Dielectric layer 1 (D1): Material: FR4 (epoxy resin glass fiber), thickness: 0.2 mm, dielectric constant (εr): 4.3, loss tangent (tan δ): 0.02; Ground layer (reference layer, L2): Material: copper foil, thickness: 0.035 mm (35 μm), electrical characteristics: ideal conductive material; Dielectric layer 2 (D2): material: FR4, thickness: 0.5 mm, dielectric constant (εr): 4.3, loss tangent (tanδ): 0.02; Signal layer 2 (L3): Material: copper foil, thickness: 0.035 mm.

[0025] It is necessary to design a microstrip line that transmits 5GHz signals, with a target impedance of 50Ω, signal layer: copper foil, thickness 0.035mm, dielectric layer: FR4, thickness 0.2mm, dielectric constant 4.3, loss tangent 0.02, ground layer: copper foil.

[0026] By importing these stacking information into the simulation tool, the characteristic impedance of the microstrip line is calculated. Through simulation, the characteristic impedance of the microstrip line is calculated to be 52Ω, which is close to the target 50Ω. This can be further optimized by adjusting the width of the microstrip line (for example, 0.6 mm). The S parameters in the simulation results show that S11 (reflection loss) is -20dB at 5GHz, indicating good impedance matching. At the same time, S21 (insertion loss) shows that the signal has a small loss (0.5dB) during transmission, which can be further reduced by using higher quality dielectric materials or increasing the thickness of the dielectric layer.

[0027] In the imported stacking information, clearly mark which layers are signal layers and which are reference layers (such as power layers and ground layers). Reference layers are usually used to provide reference potentials for signals to reduce electromagnetic interference. For example, the signal layer is set to layer 3, and the reference layer is set to layers 2 and 4. The signal layer is used to carry the transmitted signal, while the reference layer (usually the ground layer or power layer) is used to provide a return path for the signal. During the design process, it is necessary to clearly identify which layers are signal layers and which layers are reference layers to ensure that the return path of each signal is clear and stable. Reasonable reference layer distribution helps reduce electromagnetic interference and improve the quality of signal transmission.

[0028] Example: Signal layer 1 (L1): used to transmit lower-speed control signals or clock signals. These signals do not require particularly high frequency control, but still require a reference ground layer (L2) to reduce interference and provide a return path for the signal; Reference layer 1 (L2): as the ground plane of the L1 layer, it provides a stable return path to ensure that the single-ended signal of the L1 layer has a clear reference potential and reduce ground loop noise and electromagnetic interference; Signal layer 2 (L3): used to transmit high-speed differential signals. Differential signal lines are arranged in pairs, and the impedance of the signal path is controlled by the spacing between the L3 layer and the L4 layer and the characteristics of the dielectric layer. The differential signal lines of the L3 layer work with the power reference layer of the L4 layer to ensure that the signal has a good return path and stable impedance; Reference layer 2 (L4): as the power layer (VCC), it provides a reference potential for the high-speed differential signal of L3. When transmitting differential signals, the reference of the signal can usually be either the ground layer or the power layer, depending on the impedance matching requirements of the design.

[0029] Set the pattern and parameters of the routing on each signal layer, such as the width and spacing of the routing. Common patterns include single signal lines, differential signal lines, etc. For example, differential signal lines are used on signal layer 3, with a line width of 0.2mm and a line spacing of 0.15mm; routing pattern refers to the wiring form of signal routing, such as single-ended routing, differential routing, or multi-signal routing. This step requires defining the width, spacing, number of layers, and routing layout of each layer for each routing. For example, differential signal lines usually appear in pairs, and the line width and spacing directly affect the differential impedance and the anti-interference ability of the signal.

[0030] Extract the thickness of the dielectric material between the signal layer and the reference layer, as well as the thickness of the signal layer and the reference layer. For example, the signal layer thickness is 35μm and the dielectric layer thickness is 0.2mm. Extract the thickness of each layer, layer height and other geometric parameters from the imported stacking information. The distance between the signal layer and the reference layer is an important factor affecting the characteristic impedance. The material thickness and dielectric constant determine the delay and loss characteristics of the signal during transmission.

[0031] Extract the key parameters of each trace in the signal layer, such as line width, line spacing, the direction of the trace, and whether there is a differential pair. For example, extract the differential line width of 0.2mm and the spacing of 0.15mm on signal layer 3; extract the key parameters of each signal layer, such as the line width, spacing, and shape of the trace. These parameters are crucial in circuit design and directly determine the impedance and signal coupling characteristics of the transmission line. For example, the spacing and line width of the differential line need to be precisely controlled to achieve good signal integrity and noise immunity.

[0032] Determine the arrangement of each signal line, such as SSS (single line, single ground), SGSG (single line, single ground, single line, single ground) and other modes, and calculate the arrangement position of the routing according to parameters such as routing width and spacing. For example, in the SGSG mode, a reference ground line is inserted between each signal line and the adjacent signal line; according to the form of the routing pattern (such as SSS, SGSG, etc.), determine the arrangement of each signal line and its relative position. In a multi-layer design, the position and arrangement of the signal line and the reference layer directly affect the crosstalk and coupling between signals.

[0033] Example: Layout of SG arrangement mode: In SGSG mode, a reference ground line (GND) is inserted between each signal line. For example, the first signal line transmits signal 1 with a width of 0.2 mm, followed by a ground line as a reference layer with a width of 0.2 mm, providing a return path for signal 1. The second signal line transmits signal 2 with a width of 0.2 mm. The third ground line continues to provide a reference potential for signal 2.

[0034] This arrangement effectively reduces the crosstalk between signal 1 and signal 2 because the ground line (GND) provides electromagnetic isolation between the signal lines.

[0035] Calculation of arrangement position: The starting position of the first signal line can be set to X = 0, and the position of the second ground line is on the right side of the first signal line, with a spacing of 0.15 mm. Therefore, the center position of the ground line is X = 0.2 + 0.15 = 0.35 mm. The position of the second signal line is on the right side of the ground line, with a distance of 0.15 mm. Therefore, the center position of the signal line is X = 0.35 + 0.2 + 0.15 = 0.7 mm. Continuing this arrangement pattern, the position of the next ground line is X = 0.7 +0.2 + 0.15 = 1.05 mm, and so on.

[0036] The midpoint of the first signal line is used as the zero point of the x-axis of the entire transmission line model, and the relative positions of other lines are determined based on this point. For example, the first signal line is located at x=0mm. The midpoint of the first signal line is selected as the zero point of the x-axis, which is used as the position reference for other signal lines and reference layers in the model. This step provides a reference for the position arrangement of the subsequent layers.

[0037] Determine the position of the subsequent signal layers relative to the first signal layer. For example, if the second-layer signal line is offset 0.3mm to the right relative to the first signal layer, set its x position to 0.3mm; based on the position of the first signal line, calculate the relative position of other signal lines on the x-axis. This step requires ensuring that the relative position of each layer of signal lines is accurate, especially in multi-layer circuits, where the lateral offset of each layer of routing will affect the transmission characteristics of the signal.

[0038] Using the width, x-direction position, and layer height information of the trace, draw the graph of each trace on the xz plane. For example, in the xz plane, the x position of signal line 1 is 0 mm, and the x position of signal line 2 is 0.3 mm. Based on the x-axis coordinates of each layer of signal lines and the height information of the stack, construct the geometric shape of each signal line on the xz plane. This geometric model directly affects the accuracy of electromagnetic simulation calculations.

[0039] According to the position and material thickness information of the reference layer, the geometry of the reference layer on the xz plane is constructed. For example, the reference layer is located at z = 0.2 mm and has a thickness of 35 μm. The reference layer is usually located above and below the signal layer and is responsible for providing a stable current return path. According to the layer height, thickness and other parameters of the reference layer, its geometry on the xz plane is constructed.

[0040] Combining all the previous steps, the overall modeling of the signal line and the reference layer in the xz plane is completed, providing a complete transmission line geometry model that can be used for subsequent electromagnetic field simulation or analysis. After completing the geometric modeling of the signal layer and the reference layer, combined with the layout and parameters of all layers, the construction of the entire 2D transmission line model is finally completed. This model can be used for subsequent electromagnetic field simulation and electrical performance analysis.

[0041] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A 2D transmission line modeling method based on routing pattern, characterized in that: The method comprises the following steps: S1: import process stack; S2: Specify signal and reference layers in the process stack; S3: Set the signal layer routing pattern parameters; S4: Complete 2D transmission line modeling based on signal lines and reference layers.

2. The 2D transmission line modeling method based on routing pattern according to claim 1, characterized in that: The process stack includes: the type, thickness and electrical characteristics of each layer of material.

3. The 2D transmission line modeling method based on routing pattern according to claim 1, characterized in that: The reference layer is usually used to provide a reference potential for the signal to reduce electromagnetic interference; the signal layer is used to carry the transmitted signal; and the reference layer is used to provide a return path for the signal.

4. The 2D transmission line modeling method based on routing pattern according to claim 1, characterized in that: The signal layer is composed of a signal layer L1 and a signal layer L3; the reference layer is composed of a reference layer L2 and a reference layer L4; The signal layer L1 is used to transmit a relatively low-speed control signal or clock signal. The signal does not require particularly high frequency control, but still needs to refer to the ground layer L2 to reduce interference and provide a return path for the signal. The reference layer L2 serves as the ground plane of the L1 layer, providing a stable return path, ensuring that the single-ended signal of the L1 layer has a clear reference potential, and reducing ground loop noise and electromagnetic interference; The signal layer L3 is used to transmit high-speed differential signals; the differential signal lines are arranged in pairs, and the impedance of the signal path is controlled by the distance between the L3 layer and the L4 layer and the characteristics of the dielectric layer; The differential signal line of the signal layer L3 works together with the power reference layer of the reference layer L4 to ensure that the signal has a good return path and stable impedance; The reference layer L4 is used as a power layer to provide a reference potential for the high-speed differential signal of L3; When the differential signal is transmitted, the reference of the signal can usually be either a ground layer or a power layer.

5. The 2D transmission line modeling method based on routing pattern according to claim 1, characterized in that: The signal layer routing pattern parameters include single signal lines and differential signal lines; the routing pattern is the wiring form of the signal routing.

6. The 2D transmission line modeling method based on routing pattern according to claim 1, characterized in that: The thickness of the dielectric material between the signal layer and the reference layer, as well as the thickness of the signal layer and the reference layer are extracted.

7. The 2D transmission line modeling method based on routing pattern according to claim 6, characterized in that: Extract key parameters of each routing line in the signal layer; the key parameters include: line width, line spacing, routing direction, and whether there is a differential pair.

8. The 2D transmission line modeling method based on routing pattern according to claim 5, characterized in that: Determine the wiring form of each signal line, the wiring form includes: SSS (single line, single ground) mode, SGSG (single line, single ground, single line, single ground) mode; Calculate the arrangement position of the traces based on parameters such as trace width and spacing.

9. The 2D transmission line modeling method based on routing pattern according to claim 8, characterized in that: The calculation process of the arrangement position is as follows: the starting position of the first signal line can be set to X = 0, the position of the second ground line is on the right side of the first signal line, with a spacing of 0.15 mm, so the center position of the ground line is X = 0.2 + 0.15 = 0.35 mm, the position of the second signal line is on the right side of the ground line, with a distance of 0.15 mm, so the center position of the signal line is X = 0.35 + 0.2 + 0.15 = 0.7 mm, and continuing this arrangement mode, the position of the next ground line is X = 0.7 + 0.2 +0.15 = 1.05 mm.

10. The 2D transmission line modeling method based on routing pattern according to claim 1, characterized in that: The process of completing the 2D transmission line modeling according to the signal line and the reference layer is as follows: the middle point of the routing line in the first signal layer is used as the x-axis zero point of the entire transmission line model, and the relative positions of other routing lines are determined based on this, and the middle point of the first signal line is selected as the x-axis zero point, which is used as the position reference of other signal lines and reference layers in the model; Determine the position of subsequent signal layers relative to the first signal layer; calculate the relative position of other signal lines on the x-axis based on the position of the first signal line; Use the width, x-direction position, and layer height information of the trace to draw a graph of each trace on the xz plane; construct the geometric shape of each signal line on the xz plane based on the x-axis coordinates of each layer of signal lines and the height information of the stack; According to the position and material thickness information of the reference layer, the geometric figure of the reference layer on the xz plane is constructed. The reference layer is usually located above and below the signal layer and is responsible for providing a stable current return path; According to the layer height, thickness and other parameters of the reference layer, its geometry on the xz plane is constructed.

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