JP7690571B2 - Method, system, device and medium for calculating differential impedance of grid shielding structure - Google Patents

Description

The present invention relates to the technical field of calculating differential impedance, and in particular to a method and system for calculating the differential impedance of a grid shielding structure, an electronic device, and a computer-readable storage medium.

With the popularity of personal computers, liquid crystal display technology has developed rapidly in the 21st century, and with the rapid development of the communication industry, the signal transmission speed is getting faster and faster, the requirements for operating frequency and transmission quality are getting higher and higher, and at the same time, the types and features of light-speed transmission structures are also increasing. In FPC boards, in order to improve the flexibility of the board and prevent the copper surface of the large copper surface shielding layer from cracking during the bending process, the shielding layer is usually designed in a grid shape to improve the toughness of the board. In the transmission of high frequency signals, the signal layer (i.e., wiring layer) and the ground layer (i.e., shielding layer) are transmitted by the electromagnetic radiation of high frequency signals. According to the measurement principle of typical transmission line characteristic impedance and TDR (Time Domain Reflectometry), the high frequency signal is radiated from the signal line, and the signal is not only forwardly transmitted in the lead wire, but also radiated to the ground, and the induced signal received by the ground returns to the measurement end (the measurement end and the transmission end have a common port), and the line impedance value is calculated according to the level intensity of the transmitted signal and the reflected signal. Generally, the reflectance is _expressed as ρ= _Vreflected /Vincident, and the measured impedance is measured as Z= _Zref *(1+ρ)/(1-ρ), where ρ is the signal reflectance, _Vreflected is the level intensity of the reflected received signal, _Vincident is the level intensity of the transmitted signal, and _Zref is the reference resistance, which is usually 50ohm. For a large metal shielding layer structure, the reflection path in the large copper plane is consistent with the length of the transmission line, and the reflected signal intensity loss is mainly caused by the dielectric loss and conductor surface loss. In the impedance design stage, the characteristic impedance of the differential microstrip line with the large copper shielding layer structure is generally calculated by the typical differential microstrip line characteristic impedance calculation formula.
Here, a typical formula for calculating the characteristic impedance of a differential microstrip line is expressed by the following formula.
_Z0 represents a single-ended microstrip line and is expressed by the following equation:
In the formula, _εr represents the dielectric constant of the dielectric layer, h represents the thickness of the dielectric layer, t represents the copper thickness of the single-ended microstrip line, w represents the width of the single-ended microstrip line, and d represents the spacing between the edges of the two single-ended microstrip lines.

However, for grid shielding structures, after the grid shielding structure with mesh receives the reflected signal, it is distributed by the electromagnetic signal line and shows a uniform distribution in the local space, that is, dφ tends to be uniformly distributed in a single square area (the size of the grid with dimensions a+b, a represents the conductor width of the grid shielding layer, and b represents the spacing between the conductors of the grid shielding layer). Therefore, when a signal is transmitted to the shielding layer, part of it is received and returned by the shielding layer, and the other part is radiated and dissipated by the mesh, resulting in a change in the return signal strength and affecting the calculation of the impedance value. Therefore, the characteristic impedance calculation formula of a typical differential microstrip line is not suitable for the grid shielding structure.

The present invention provides a method and system for calculating the differential impedance of a grid shielded structure, an electronic device, and a computer-readable storage medium, and solves the conventional technical problem that the characteristic impedance calculation formula for a typical differential microstrip line is not suitable for a grid shielded structure.

According to one aspect of the present invention, there is provided a method for calculating a differential impedance of a grid shielding structure, the method comprising:
Obtaining the conductor width and spacing of the grid shielding layer, and calculating a dissipation ratio of the signal dissipation amount of the grid shielding layer to the signal transmission amount of the power supply ground layer;
obtaining a dielectric thickness parameter for the dielectric layer, equating the signal dissipation of the grid shielding layer with an increase in dielectric thickness, and calculating an equivalent dielectric thickness based on the dissipation factor and the dielectric thickness parameter;
Obtain the included angle between the differential line and the horizontal side of the grid shielding layer, the dielectric constant of the dielectric layer, and calculate the equivalent dielectric constant according to the time equivalence principle of the network transmission of the power and ground layer circuit;
Obtaining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, and calculating the differential impedance based on the equivalent dielectric thickness, the equivalent dielectric constant and a typical differential microstrip line characteristic impedance calculation formula.

Furthermore, the differential impedance is calculated based on the following formula:

where _Z2 represents the differential impedance of the grid shielding structure, _ε'r represents the equivalent dielectric constant, _εr represents the dielectric constant of the dielectric layer, h' represents the equivalent dielectric thickness, w and t represent the width and copper thickness of the differential lines, and d represents the edge spacing between the two differential lines.

Furthermore, one of the differential lines has a curved portion, and both the span and height of the curved portion are smaller than the spacing of the grid shielding layer.

Furthermore, the specific process for calculating the dissipation rate is as follows:

Since the electromagnetic signal lines are uniformly distributed in a single grid area, the dissipation ratio of the actual signal dissipation to the signal transmission in a single grid area is proportional to the receiving area, i.e., η=φ ₁ /φ _total =S ₁ /S _total .
In the formula, η represents the dissipation factor, _φ1 and _φtotal represent the signal dissipation and signal transmission, respectively, _S1 and _Stotal represent the mesh area and total area, respectively, within a single grid region, _S1 = ^b2 , _Stotal = (a + b) ² , a and b represent the conductor width and spacing, respectively, of the grid shielding layer, and η = ^b2 / (a + b) ² .

Furthermore, the equivalent dielectric thickness is calculated based on the following formula:

In the formula, h' represents the equivalent dielectric thickness and h represents the dielectric thickness parameter of the dielectric layer.

Furthermore, the process of calculating the equivalent dielectric constant based on the time equivalence principle of the network transmission of the power supply ground layer circuit is specifically as follows:

For a single grid, the actual transit time of an electrical signal is given by:
V is expressed by the following equation (6).
In the above formula (6), c represents the speed of light, _εr represents the dielectric constant of the dielectric layer, and θ represents the included angle between the differential line and the horizontal side of the grid shielding layer. If l represents the length of the hypotenuse of a single grid, and based on the time equivalence principle of the network transmission of the power and ground layer circuit, assuming that the transmission length is still 2l, t can be expressed by the following formula (7).
_ε′r represents the equivalent dielectric constant and is expressed by the following equation (Equation 8).

Furthermore, the total width of the grid shield layer is infinite relative to the differential line, or the grid shield layer has a dielectric thickness three times larger on at least one side in the width direction than the differential line, and a line width three times larger.

The present invention further provides a system for calculating the differential impedance of a grid shielding structure, said system comprising:
a dissipation factor calculation module for obtaining a conductor width and a spacing of the grid shielding layer and calculating a dissipation factor of a signal dissipation amount of the grid shielding layer relative to a signal transmission amount of the power supply ground layer;
an equivalent dielectric thickness calculation module for obtaining a dielectric thickness parameter of the dielectric layer, equating a signal dissipation of the grid shielding layer with an increase in dielectric thickness, and calculating an equivalent dielectric thickness based on the dissipation factor and the dielectric thickness parameter;
an equivalent dielectric constant calculation module for obtaining the included angle between the differential line and the horizontal side of the grid shielding layer and the dielectric constant of the dielectric layer, and calculating the equivalent dielectric constant according to the time equivalence principle of the network transmission of the power supply ground layer circuit;
and a differential impedance calculation module for obtaining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, and calculating the differential impedance based on the equivalent dielectric thickness, the equivalent dielectric constant and a characteristic impedance calculation formula for a typical differential microstrip line.

The present invention also provides an electronic device including a processor and a storage device, the storage device storing a computer program, and the processor being used to execute the steps of the aforementioned method by calling up the computer program stored in the storage device.

The present invention also provides a computer-readable storage medium for storing a computer program for performing a calculation of the differential impedance of a grid shielding structure, the computer program performing the steps of the aforementioned method when executed on a computer.

The present invention has the following advantages:

In the method for calculating the differential impedance of the grid shielding structure of the present invention, when a signal is transmitted to the grid shielding layer, part of it is received and returned by the grid shielding layer, and the other part is radiated and dissipated by the mesh of the grid shielding layer, so that the return signal strength changes and affects the calculation of the impedance value. Therefore, in the present invention, first, the dissipation rate of the signal dissipation amount of the grid shielding layer relative to the signal transmission amount of the power supply ground layer is calculated based on the conductor width and spacing of the grid shielding layer, then the signal dissipation of the grid shielding layer is equivalent to the increase in the dielectric thickness of the dielectric layer, and as a result, the equivalent dielectric thickness is calculated based on the dissipation rate and dielectric thickness parameters, and then the equivalent dielectric constant of the grid shielding structure is calculated for the large copper plane shielding layer based on the time equivalence principle of the network transmission of the power supply grounding layer circuit, which is different from the dielectric constant of the pure dielectric between the transmission lines, and finally, the differential impedance of the grid shielding structure is calculated by combining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, the equivalent dielectric thickness, the equivalent dielectric constant and the characteristic impedance calculation formula of a typical differential microstrip line of the large copper plane shielding layer. This invention proposes for the first time a calculation theory and calculation model for the differential impedance of a grid shielding structure, taking into account the influence of the dissipative effect of the grid shielding layer on the calculation of differential impedance, making the signal dissipation of the grid shielding layer equivalent to the increase in dielectric thickness, and at the same time, calculating the equivalent dielectric constant of the grid shielding structure for the large copper surface shielding layer based on the time equivalence principle of the network transmission of the power supply ground layer circuit, greatly improving the calculation accuracy of the differential impedance of the grid shielding structure, which can be successfully applied to the differential line design of the grid shielding structure, and helping to improve the first-time pass rate of differential impedance design.

The differential impedance calculation system, electronic device, and computer-readable storage medium of the present invention also have the above-mentioned advantages.

In addition to the above objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be described in more detail below with reference to the drawings.

The drawings forming a part of this application are used to provide a further understanding of the present invention, and the exemplary embodiments of the present invention and their explanations are used to interpret the present invention and are not intended to limit the present invention.

1 is a schematic cross-sectional view of a grid shielding structure according to a preferred embodiment of the present invention; FIG. 2 is a schematic diagram of a preferred embodiment of the present invention in which the differential lines and the horizontal edge of the grid shielding layer are arranged at an angle. FIG. 2 is a schematic diagram of a method flow for calculating the differential impedance of a grid shielding structure according to a preferred embodiment of the present invention. FIG. 2 is a schematic diagram showing a case where a curved portion is provided in one differential line in a preferred embodiment of the present invention. FIG. 13 is a schematic diagram of a modular structure of a system for calculating differential impedance of a grid shielding structure according to another embodiment of the present invention.

The following detailed description of the preferred embodiment of the present invention will be given with reference to the drawings. However, the present invention can be implemented in several different ways, which are limited and covered below.

In addition, an embodiment of the present invention provides a method for calculating the differential impedance of a grid shielding structure. As shown in Figures 1 and 2, an impedance line structure with a grid shielding structure specifically includes a wiring layer, a dielectric layer and a grid shielding layer, the wiring layer and the grid shielding layer are respectively provided on both sides of the dielectric layer, and two differential lines are designed in the wiring layer, which are generally two single-ended microstrip lines, and the grid shielding layer is an orthogonal square grid conductor. Preferably, the grid shielding layer is infinite relative to the differential lines in the width direction, or the grid shielding layer has a dielectric thickness three times larger than the differential lines on at least one side in the width direction, and a line width three times larger. As shown in Figure 3, the method for calculating the differential impedance of the grid shielding structure specifically includes:
Step S1: obtaining a conductor width and a spacing of the grid shielding layer, and calculating a dissipation ratio of a signal dissipation amount of the grid shielding layer to a signal transmission amount of a power supply ground layer;
S2, obtaining a dielectric thickness parameter of the dielectric layer, equating the signal dissipation of the grid shielding layer with an increase in dielectric thickness, and calculating an equivalent dielectric thickness based on the dissipation factor and the dielectric thickness parameter;
Step S3: obtain the included angle between the differential line and the horizontal side of the grid shielding layer, the dielectric constant of the dielectric layer, and calculate the equivalent dielectric constant according to the time equivalence principle of the network transmission of the power supply/ground layer circuit;
and step S4 of obtaining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, and calculating the differential impedance based on the equivalent dielectric thickness, the equivalent dielectric constant and a typical characteristic impedance calculation formula for a differential microstrip line.

In addition, in the method for calculating the differential impedance of the grid shielding structure of this embodiment, when a signal is transmitted to the grid shielding layer, part of it is received and returned by the grid shielding layer, and the other part is radiated and dissipated by the mesh of the grid shielding layer, so that the return signal strength changes and affects the calculation of the impedance value. Therefore, in the present invention, first, the dissipation rate of the signal dissipation amount of the grid shielding layer relative to the signal transmission amount of the power supply ground layer is calculated based on the conductor width and spacing of the grid shielding layer, then the signal dissipation of the grid shielding layer is equivalent to the increase in the dielectric thickness of the dielectric layer, and as a result, the equivalent dielectric thickness is calculated based on the dissipation rate and dielectric thickness parameters, and then the equivalent dielectric constant of the grid shielding structure relative to the power supply ground layer of the large copper plane shielding layer is calculated based on the time equivalence principle of the network transmission of the power supply grounding layer circuit, and finally, the differential impedance of the grid shielding structure is calculated by combining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, the equivalent dielectric thickness, the equivalent dielectric constant and the characteristic impedance calculation formula of a typical differential microstrip line of the large copper plane shielding layer. This invention proposes for the first time a calculation theory and calculation model for the differential impedance of a grid shielding structure, taking into account the impact of the dissipative effect of the grid shielding layer on the calculation of differential impedance, making the signal dissipation of the grid shielding layer equivalent to the increase in dielectric thickness, and at the same time, calculating the equivalent dielectric constant of the grid shielding structure for the large copper surface shielding layer based on the time equivalence principle of the network transmission of the power ground layer circuit, which is different from the dielectric constant of the pure dielectric between the transmission lines, greatly improving the calculation accuracy of the differential impedance of the grid shielding structure, which can be successfully applied to the differential line design of the grid shielding structure, and helping to improve the first-time pass rate of differential impedance design.

In addition, in step S1, since the electromagnetic signal lines are uniformly distributed in a single grid area (i.e., the size of a + b dimension grid) in the grid shielding layer, after the signal is transmitted to the grid shielding layer, the dissipation rate of the actual signal dissipation amount relative to the signal transmission amount in a single grid area is proportional to the receiving area, that is, it can be expressed by the following formula:
In the formula, _φ1 and _φtotal represent the signal dissipation and signal transmission, respectively, _S1 and _Stotal represent the mesh area and total area in a single grid region, respectively, and a and b represent the conductor width and spacing of the grid shielding layer, respectively. Therefore, by simply inputting the conductor width a and spacing b of the grid shielding layer, the dissipation factor can be calculated based on the following formula (Equation 10).

In the above formula, η represents the dissipation rate.

It should be noted that, in step S2, as can be seen from the above formula (Formula 11), which is the typical differential microstrip line characteristic impedance calculation formula of the large copper plane shielding layer, the characteristic impedance _Z0 of the single-ended microstrip line is inversely proportional to the width w of the microstrip line, the copper thickness t and the dielectric constant _εr of the dielectric layer, and is proportional to the dielectric thickness h. The larger the dielectric thickness h, the smaller the signal reception amount is, and the signal reception amount is directly related to the spacing of the power ground layer (i.e., the distance from the power ground layer to the grid shielding layer), and the increase in the grid is equivalent to the increase in the spacing of the power ground layer. Therefore, after changing the large copper plane shielding layer to the grid shielding layer, the radiation and dissipation of the signal can be made equivalent to the increase in the dielectric thickness. Therefore, the dielectric thickness parameters of the dielectric layer can be input, and specifically, the equivalent dielectric thickness can be calculated according to the following formula (Formula 12).

In the formula, h' represents the equivalent dielectric thickness, h represents the dielectric thickness parameter of the dielectric layer, and η represents the dissipation factor.

It should be noted that in step S3, from the viewpoint of the power supply and ground layer circuit, the characteristic impedance transmission line is still a straight line in the dielectric layer, but the transmission path of the grid shielding layer is affected by the angle between the transmission line and the grid.Specifically, in a single grid, the signal is transmitted along the side of the right triangle of the single grid, and as can be seen from the relationship between the hypotenuse and the short side of the right triangle, the signal transmission length of the grid shielding layer is l (cosθ+sinθ), where θ represents the included angle between the differential line and the horizontal side of the grid shielding layer, and l represents the length of the hypotenuse of the right triangle.Combined with the transmission speed of the electrical signal in the medium, the following formula (Formula 13) is obtained:
where c represents the speed of light, and ε _r represents the dielectric constant of the dielectric layer. Therefore, the actual transmission time of an electrical signal is given by the following equation (Equation 14):
Based on the time equivalence principle of the network transmission of the power/ground layer circuit, if the transmission length is still 2l, t can be expressed by the following equation (Equation 15):
_ε′r represents the equivalent dielectric constant and is expressed by the following equation (Equation 16).

Note that the differential impedance is called the differential mode impedance, which includes the superposition of the characteristic impedance of two single-ended microstrip lines and the coupling attenuation due to differential mode induction between the two single-ended microstrip lines, i.e., the former is the impedance to ground, and the latter can be understood as the impedance attenuation of one differential line to the other differential line. This can be seen from the characteristic impedance calculation formula for a typical differential microstrip line with a large copper surface shielding layer.

where _Z1 represents the differential impedance of the large copper plane shielding layer structure, _εr represents the equivalent dielectric constant of the dielectric layer, h represents the thickness of the dielectric layer (abbreviated as dielectric thickness), w and t represent the width and copper thickness of the differential lines, and d represents the edge spacing between the two differential lines.

The above formula can be broken down as follows:

In the above formula (Formula 18), the first half (shown in Formula 19) represents the superposition of the characteristic impedances of two single-ended microstrip lines.
Moreover, in the above formula (Formula 18), the latter half (shown in Formula 20) represents the attenuation value of the equivalent characteristic impedance between two single-ended microstrip lines.

For the grid shielding structure, since the mesh of the grid shielding layer has signal dissipation, the signal dissipation is equivalent to an increase in the equivalent dielectric thickness, and when calculating the characteristic impedance of each single-ended microstrip line, the transmission of the power supply ground layer circuit must be taken into consideration. Therefore, when calculating the superposition of the characteristic impedance of two single-ended microstrip lines, it is necessary to calculate through the equivalent dielectric thickness and equivalent dielectric constant. Since the differential mode induction between the two single-ended microstrip lines exists only in the power supply layer (wiring layer) and is not affected by the shielding layer structure, when calculating the attenuation value of the equivalent characteristic impedance between the two single-ended microstrip lines, the effect of the equivalent dielectric constant is not taken into consideration, but only the effect of the equivalent dielectric thickness is taken into consideration. Therefore, in the step S4, specifically, the differential impedance of the grid shielding structure is calculated based on the following formula (Math. 21).

where _Z2 represents the differential impedance of the grid shielding structure, _ε'r represents the equivalent dielectric constant, and h' represents the equivalent dielectric thickness.

Next, by substituting the equivalent dielectric thickness h' and the equivalent dielectric constant _ε'r into the above equation, the following is obtained:

where _Z2 represents the differential impedance of the grid shield structure.

In order to ensure the consistency of the transmission delay between the differential mode and the differential ground and to reduce the effect of the grid shielding layer, a curved section is designed in one differential line, as shown in Figure 4, and the span and height of the curved section are both smaller than the spacing b of the grid shielding layer.

In order to verify the accuracy of the calculation model for the differential impedance of the grid shielding structure of the present invention, actual verification was performed, and a specific verification example is as follows.

In Example 1, a double panel is provided, and according to the overlapping structure of the outer layer microstrip line, the line width of the wiring layer is set to 100 μm, the interval between the edges of the two differential lines is 100 μm, the copper thickness of the transmission line is 50 μm, the dielectric constant Dk of the dielectric layer material (FR4, epoxy resin) is 4.4, its dielectric thickness is 89 μm, the conductor width a of the grid shielding layer is 1000 μm, its interval b is 1000 μm, and the included angles between the differential line and the horizontal direction of the grid are 0°, 15°, 30°, 45°, 60°, and 90°, respectively, and the measured impedance values simulated by the calculation model are shown in Table 1 below.

In Example 2, a double panel is provided, and according to the overlapping structure of the outer layer microstrip line, the line width of the wiring layer is set to 250 μm, the interval between the edges of the two differential lines is 150 μm, the copper thickness of the transmission line is 50 μm, the dielectric constant Dk of the dielectric layer material (FR4, epoxy resin) is 4.4, and its dielectric thickness is 89 μm, the conductor width a of the grid shielding layer is 1000 μm, and its interval b is 1000 μm, 2000 μm, 3000 μm, and 4000 μm, respectively, and the included angle between the differential line and the horizontal direction of the grid is 0°, and the measured impedance value simulated by the calculation model is shown in Table 2 below.

As can be seen from the above actual verification results, the calculation accuracy of the differential impedance calculation model of the grid shielding structure of the present invention is very high.

In addition, as shown in FIG. 5, another embodiment of the present invention further provides a system for calculating differential impedance of a grid shielding structure, preferably using the above-mentioned method for calculating differential impedance, the system includes:
a dissipation factor calculation module for obtaining a conductor width and a spacing of the grid shielding layer and calculating a dissipation factor of a signal dissipation amount of the grid shielding layer relative to a signal transmission amount of the power supply ground layer;
an equivalent dielectric thickness calculation module for obtaining a dielectric thickness parameter of the dielectric layer, equating a signal dissipation of the grid shielding layer with an increase in dielectric thickness, and calculating an equivalent dielectric thickness based on the dissipation factor and the dielectric thickness parameter;
an equivalent dielectric constant calculation module for obtaining the included angle between the differential line and the horizontal side of the grid shielding layer and the dielectric constant of the dielectric layer, and calculating the equivalent dielectric constant according to the time equivalence principle of the network transmission of the power supply ground layer circuit;
and a differential impedance calculation module for obtaining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, and calculating the differential impedance based on the equivalent dielectric thickness, the equivalent dielectric constant and a characteristic impedance calculation formula for a typical differential microstrip line.

In addition, in the calculation system for the differential impedance of the grid shielding structure of this embodiment, when a signal is transmitted to the grid shielding layer, part of it is received and returned by the grid shielding layer, and the other part is radiated and dissipated by the mesh of the grid shielding layer, so that the return signal strength changes and affects the calculation of the impedance value. Therefore, in the present invention, first, the dissipation rate of the signal dissipation amount of the grid shielding layer relative to the signal transmission amount of the power supply ground layer is calculated based on the conductor width and spacing of the grid shielding layer, then the signal dissipation of the grid shielding layer is equivalent to the increase in the dielectric thickness of the dielectric layer, and as a result, the equivalent dielectric thickness is calculated based on the dissipation rate and dielectric thickness parameters, and then the equivalent dielectric constant of the grid shielding structure relative to the power supply ground layer of the large copper plane shielding layer is calculated based on the time equivalence principle of the network transmission of the power supply grounding layer circuit, and finally, the differential impedance of the grid shielding structure is calculated by combining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, the equivalent dielectric thickness, the equivalent dielectric constant and the characteristic impedance calculation formula of a typical differential microstrip line of the large copper plane shielding layer. This invention proposes for the first time a calculation theory and calculation model for the differential impedance of a grid shielding structure, taking into account the impact of the dissipative effect of the grid shielding layer on the calculation of differential impedance, making the signal dissipation of the grid shielding layer equivalent to the increase in dielectric thickness, and at the same time, calculating the equivalent dielectric constant of the grid shielding structure for the large copper plane shielding layer based on the time equivalence principle of the network transmission of the power supply ground layer circuit. This is different from the dielectric constant of the pure dielectric between the transmission lines, which greatly improves the calculation accuracy of the differential impedance of the grid shielding structure, can be successfully applied to the differential line design of the grid shielding structure, and helps to improve the first-time pass rate of differential impedance design.

Specifically, the dissipation rate calculation module calculates the dissipation rate based on the following formula:

In the formula, η represents the dissipation factor, and a and b represent the conductor width and spacing of the grid shielding layer, respectively.

The equivalent dielectric thickness calculation module calculates the equivalent dielectric thickness based on the following formula:

In the formula, h' represents the equivalent dielectric thickness, h represents the dielectric thickness parameter of the dielectric layer, and η represents the dissipation factor.

The equivalent dielectric constant calculation module calculates the equivalent dielectric constant based on the following formula:

where ε′ _r represents the equivalent dielectric constant, ε _r represents the dielectric constant of the dielectric layer, and θ represents the included angle between the impedance line and the horizontal side of the grid shielding layer.

The differential impedance calculation module calculates the differential impedance of the grid shielding structure based on the following formula:

where _Z2 represents the differential impedance of the grid shielding structure, _ε'r represents the equivalent dielectric constant, and h' represents the equivalent dielectric thickness.

Note that since each module in the system of this embodiment corresponds to each step in the embodiment of the method described above, the specific calculation principles of each module will not be described in detail, and reference may be made to the embodiment of the method described above.

In addition, another embodiment of the present invention further provides an electronic device including a processor and a storage device, the storage device storing a computer program, and the processor is used to execute the steps of the aforementioned method by calling the computer program stored in the storage device.

Another embodiment of the present invention further provides a computer-readable storage medium for storing a computer program for performing a calculation of the differential impedance of a grid shielding structure, the computer program performing the steps of the aforementioned method when executed on a computer.

Typically, computer-readable storage media may take the form of a floppy disk, a flexible disk, a hard disk, a magnetic tape, any other magnetic medium, a CD-ROM, any other optical medium, a punch card, a paper tape, any other physical medium with a pattern of holes, a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a flash memory (FLASH-EPROM), any other memory chip or cassette, or any other computer-readable storage medium. Instructions may further be transmitted or received by a transmission medium. The term transmission medium may include any tangible or intangible medium that can be used to store, encode, or carry instructions for execution by a machine, including digital or analog communication signals or intangible media that facilitate communication of such instructions. Transmission media include coaxial cables, copper wire and fiber optics, including the leads of a bus for transmitting computer data signals.

The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various modifications and changes to the present invention. Modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Those skilled in the art should understand that the embodiments of the present application may be provided as a method, a system, or a computer program product. Thus, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. The present application may also take the form of a computer program product embodied in one or more computer usable storage media (including, but not limited to, storage devices, CD-ROMs, optical storage devices, and the like) containing computer usable program code. The solutions in the embodiments of the present application may be realized using various computer languages, for example, the object-oriented programming language Java (registered trademark) and the interpreted scripting language JavaScript (registered trademark).

This application is described with reference to flowcharts and/or block diagrams of methods, devices (systems), and computer program products according to embodiments of this application. It should be understood that each flow and/or block in the flowcharts and/or block diagrams, and combinations of flows and/or blocks in the flowcharts and/or block diagrams, can be realized by computer program instructions. These computer program instructions are provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device, thereby generating an apparatus, and the instructions executed by the processor of the computer or other programmable data processing device generate an apparatus that realizes the functions specified in one or more flows of the flowcharts and/or one or more blocks of the block diagrams.

These computer program instructions can also be stored in a computer readable storage device that directs a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer readable storage device produce an article of manufacture that includes an instruction device that implements the functions specified in one or more flows of the flowcharts and/or one or more blocks of the block diagrams.

These computer program instructions may also be loaded into a computer or other programmable data processing device, such that the computer or other programmable device performs a sequence of operational steps to generate a computer-implemented process, such that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows of the flowcharts and/or one or more blocks of the block diagrams.

Although preferred embodiments of the present application are described, those skilled in the art may make additional changes and modifications to these embodiments once the basic inventive concept is known. Accordingly, it is intended that the appended claims be interpreted to cover the preferred embodiments and all changes and modifications that are within the scope of the present application.

Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and modifications of the present application are within the scope of the claims of the present application and their equivalent technologies, the present application is intended to include those modifications and modifications as well.

Claims (7)

A method for calculating differential impedance of a grid shielding structure, the grid shielding structure comprising a wiring layer, a dielectric layer, and a grid shielding layer, the wiring layer and the grid shielding layer being provided on both sides of the dielectric layer, respectively, two differential lines being designed in the wiring layer, and the grid shielding layer being an orthogonal square grid-shaped conductor, comprising:
Obtaining a conductor width and spacing of the grid shielding layer, and calculating a dissipation ratio of the signal dissipation amount of the grid shielding layer to the signal transmission amount of the power ground layer, where the signal transmission amount of the power ground layer refers to the signal transmission amount between the power layer and the ground layer, the power layer includes a wiring layer and a dielectric layer, and the ground layer is a grid shielding layer;
obtaining a dielectric thickness parameter for the dielectric layer, equating the signal dissipation of the grid shielding layer with an increase in dielectric thickness, and calculating an equivalent dielectric thickness based on the dissipation factor and the dielectric thickness parameter;
A step of obtaining the included angle between the differential line and the horizontal side in the width direction of the grid shielding layer and the dielectric constant of the dielectric layer, and calculating the equivalent dielectric constant based on the time equivalence principle of the network transmission of the power supply ground layer circuit, where the power supply ground layer circuit is a signal transmission circuit between the power supply layer and the ground layer, and the process of calculating the equivalent dielectric constant based on the time equivalence principle of the network transmission of the power supply ground layer circuit is specifically as follows:
In a single grid, the actual transmission time of an electrical signal is
and
So,
c represents the speed of light, εr _represents the dielectric constant of the dielectric layer, θ represents the included angle between the differential line and the horizontal side in the width direction of the grid shielding layer, and l represents the length of the hypotenuse of a single grid. Based on the time equivalence principle of the network transmission of the power and ground layer circuit, assuming that the transmission length is still 2l,
and
ε′r represents the equivalent dielectric constant, so that
and
Obtaining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, and calculating the differential impedance of the grid shielding structure based on the equivalent dielectric thickness, the equivalent dielectric constant and a typical differential microstrip line characteristic impedance calculation formula , calculating the differential impedance of the grid shielding structure based on the following formula:
where Z2 _represents the differential impedance of the grid shielding structure, which includes the superposition of the characteristic impedances of the two differential lines and the coupling attenuation due to differential mode induction between the two differential lines, ε'r represents _the equivalent dielectric constant, εr represents _the dielectric constant of the dielectric layer, h' represents the equivalent dielectric thickness, w and t represent the width and copper thickness of the differential lines, and d represents the edge spacing between the two differential lines;
11. A method for calculating differential impedance of a grid shielding structure, comprising: The method for calculating the differential impedance of a grid shielding structure according to claim 1, characterized in that one differential line has a curved portion, and the span and height of the curved portion are both smaller than the spacing of the grid shielding layer. The calculation process of the dissipation rate is specifically as follows:
Since the electromagnetic signal lines are uniformly distributed in a single grid area, the dissipation ratio of the actual signal dissipation amount to the signal transmission amount in a single grid area is proportional to the receiving area,
That is, η=φ ₁ /φ _total = S ₁ /S _total ,
2. The method for calculating the differential impedance of a grid shielding structure according to claim 1, characterized in that, in the formula, η represents the dissipation factor, _φ1 and _φtotal represent the signal dissipation amount and the signal transmission amount, respectively, _S1 and _Stotal represent the mesh area and the total area in a single grid region, respectively, _S1 = ^b2 , _Stotal = (a + b) ² , a and b represent the conductor width and spacing of the grid shielding layer, respectively, and η = ^b2 / (a + b) ² . Calculate the equivalent dielectric thickness based on the following formula:
4. The method for calculating the differential impedance of a grid shielding structure as claimed in claim 3 , wherein h' represents the equivalent dielectric thickness and h represents the dielectric thickness parameter of the dielectric layer. 2. The method for calculating the differential impedance of a grid shielding structure according to claim 1, wherein the grid shielding layer has a dielectric thickness three times larger than the differential line on at least one side in the width direction, and the line width is three times larger. 13. A system for calculating the differential impedance of a grid shielding structure using the method of claim 1 , comprising:
a dissipation factor calculation module for obtaining a conductor width and a spacing of the grid shielding layer and calculating a dissipation factor of a signal dissipation amount of the grid shielding layer relative to a signal transmission amount of the power supply ground layer;
an equivalent dielectric thickness calculation module for obtaining a dielectric thickness parameter of the dielectric layer, equating a signal dissipation of the grid shielding layer with an increase in dielectric thickness, and calculating an equivalent dielectric thickness based on the dissipation factor and the dielectric thickness parameter;
an equivalent dielectric constant calculation module for obtaining the angle between the differential line and the horizontal side of the grid shielding layer in the width direction and the dielectric constant of the dielectric layer, and calculating the equivalent dielectric constant according to the time equivalence principle of the network transmission of the power supply and ground layer circuit;
A differential impedance calculation module for obtaining the width of the differential line, the copper thickness and the edge spacing between the two differential lines, and calculating the differential impedance based on the equivalent dielectric thickness, the equivalent dielectric constant and a typical characteristic impedance calculation formula of the differential microstrip line;
1. A system for calculating differential impedance of a grid shielding structure, comprising: An electronic device comprising: a processor; and a storage device;
2. An electronic device, comprising: a computer program stored in the storage device; and the processor is used to execute the steps of the method of claim 1 by calling up the computer program stored in the storage device.