CN112004313A - Differential routing and design method thereof - Google Patents

Differential routing and design method thereof Download PDF

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CN112004313A
CN112004313A CN202011079146.1A CN202011079146A CN112004313A CN 112004313 A CN112004313 A CN 112004313A CN 202011079146 A CN202011079146 A CN 202011079146A CN 112004313 A CN112004313 A CN 112004313A
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signal line
impedance
differential
width
design parameter
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羊杨
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Embedway Technologies Shanghai Corp
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Embedway Technologies Shanghai Corp
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0237—High frequency adaptations
    • H05K1/0245—Lay-out of balanced signal pairs, e.g. differential lines or twisted lines

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Abstract

The application discloses a differential routing and a design method thereof, the method firstly ensures that the lengths of a first signal line and a second signal line are equal in a winding way, avoids the problem that the transmission efficiency is low due to the unequal lengths of the first signal line and the second signal line, then determines the width of a first part and the width of a third part, calculates the differential impedance of the third part and the first part, and finally determines the widths of the second part and the fourth part according to the differential impedance of the first part and the third part, a first design parameter and a second design parameter so as to match the differential impedance of the first part and the third part with the differential impedance of the second part and the fourth part, solves the problem of impedance discontinuity of the second signal line due to the winding and avoids transmission signal reflection caused by impedance discontinuity, resulting in a problem of signal transmission energy loss.

Description

Differential routing and design method thereof
Technical Field
The present application relates to the field of integrated circuit technology, and more particularly, to a differential trace and a design method thereof.
Background
The differential coupling lines, also called differential lines, refer to lines for transmitting differential signals. The differential coupling line generally includes two signal lines, and the driving end sends two signals with equal value and opposite phase to the two signal lines, and transmits the signals to the receiving end through the differential signal line. The receiving end judges whether the logic state is '0' or '1' by comparing the difference value of the two signals.
When high-speed signals are transmitted, compared with a single-ended line, the differential coupling line has the advantages of being high in anti-interference capacity, capable of achieving low-voltage transmission and the like, and is widely applied to computer buses and communication equipment.
However, in the process of designing the differential trace, the length of two signal lines of the differential trace may be different and the impedance may be discontinuous, which may adversely affect the performance of the differential trace.
Disclosure of Invention
In order to solve the technical problem, the present application provides a differential routing and a design method thereof to solve the problems of unequal lengths of two signal lines and discontinuous impedance of the differential routing.
In order to achieve the technical purpose, the embodiment of the application provides the following technical scheme:
a method of designing a differential trace, comprising:
determining first design parameters of a first signal line, wherein the first design parameters comprise the length, the thickness and the material dielectric constant of the first signal line;
determining second design parameters of a second signal line, wherein the second design parameters comprise the length, the thickness and a material node constant of the second signal line;
designing a first portion and a second portion of the second signal line, a distance between the second portion and the fourth portion being greater than a distance between the first portion and the third portion, so that a length of the first signal line is equal to a length of the second signal line;
designing a third part and a fourth part of the first signal line, wherein the width of the third part is smaller than that of the fourth part;
determining widths of the first portion and the third portion, and determining differential impedances of the first portion and the third portion based on the first design parameter, the second design parameter, and the widths of the first portion and the third portion;
determining widths of the second portion and the fourth portion according to differential impedances of the first portion and the third portion, the first design parameter, and the second design parameter to match the differential impedances of the first portion and the third portion and the second portion and the fourth portion.
Optionally, the determining widths of the first portion and the third portion, and determining a differential impedance of the first portion and the third portion according to the first design parameter, the second design parameter, and the widths of the first portion and the third portion includes:
setting a width of the first portion to be the same as a width of the third portion;
calculating an impedance of the first signal line according to the first design parameter and a width of the third portion;
calculating an impedance of the first portion of the second signal line according to the second design parameter and a width of the first portion of the second signal line;
calculating a differential impedance of the third portion of the first signal line and the first portion of the second signal line from the impedance of the third portion of the first signal line, the impedance of the first portion of the second signal line, and a distance between the third portion of the first signal line and the first portion of the second signal line.
Optionally, the calculating the impedance of the first portion of the second signal line according to the second design parameter and the width of the first portion of the second signal line includes:
substituting the second design parameter and the width of the first part of the second signal line into a first preset formula to calculate and obtain the impedance of the first part of the second signal line;
the first preset formula includes:
Figure BDA0002717342910000031
wherein Z is21Representing the impedance of the first part of the second signal line, W21Denotes the width of the first portion of the second signal line, Er denotes the dielectric constant of the material, T2The thickness of the second signal line is indicated, and H indicates the thickness of the substrate carrying the differential signal lines.
Optionally, the calculating the impedance of the first signal line according to the first design parameter and the width of the third portion includes:
substituting the first design parameter and the width of the third part into a second preset formula to calculate and obtain the impedance of the first signal line;
the second preset formula includes:
Figure BDA0002717342910000032
wherein Z is1Represents an impedance of a third portion of the first signal line, W1Denotes the width of the third portion of the first signal line, Er denotes the dielectric constant of the material, T1The thickness of the third portion of the first signal line is indicated, and H indicates the thickness of the substrate carrying the differential signal lines.
Optionally, the calculating the differential impedance of the third portion of the first signal line and the first portion of the second signal line according to the impedance of the third portion of the first signal line, the impedance of the first portion of the second signal line, and the distance between the third portion of the first signal line and the first portion of the second signal line includes:
substituting the impedance of the third part of the first signal line, the impedance of the first part of the second signal line and the distance between the third part of the first signal line and the first part of the second signal line into a third preset formula to calculate and obtain the differential impedance of the third part of the first signal line and the first part of the second signal line;
the third preset formula includes:
Figure BDA0002717342910000033
where Zdiff represents a differential impedance of the third portion of the first signal line and the first portion of the second signal line, and D1 represents a distance between the third portion of the first signal line and the first portion of the second signal line.
Optionally, the determining widths of the second portion and the fourth portion according to the differential impedance of the first portion and the third portion, the first design parameter, and the second design parameter, so that the differential impedance of the first portion and the third portion and the differential impedance of the second portion and the fourth portion are matched includes:
substituting the differential impedance of the third part of the first signal line and the first part of the second signal line, the first design parameter and the second design parameter into a fourth preset formula to calculate and obtain the width of the second part of the second signal line;
the fourth preset formula includes:
Figure BDA0002717342910000041
wherein, W22Denotes a width of the second portion of the second signal line and a width of the fourth portion of the first signal line, D2 denotes a distance between the second portion of the second signal line and the fourth portion of the first signal line, T2The thickness of the second signal line is indicated.
A differential trace, comprising: a first signal line and a second signal line; wherein the content of the first and second substances,
the second signal line comprises a first part and a second part, the distance between the first part of the second signal line and the third part of the first signal line is a first distance, the distance between the second part of the second signal line and the fourth part of the first signal line is a second distance, and the first distance is smaller than the second distance;
the first signal line includes a third portion and a fourth portion, a width of the third portion being smaller than a width of the fourth portion; and a width of the first portion of the second signal line is smaller than a width of the second portion of the second signal line to match a differential impedance of the first portion and the third portion with a differential impedance of the second portion and the fourth portion.
Optionally, the width of the second portion of the second signal line is determined by a fourth preset formula;
the fourth preset formula includes:
Figure BDA0002717342910000051
wherein Er represents the dielectric constant of the material, T2Denotes the thickness of the second signal line, H denotes the base carrying the differential signal lineThickness of the plate, W22Denotes a width of the second portion of the second signal line and a width of the fourth portion of the first signal line, and D2 denotes a distance between the second portion of the second signal line and the fourth portion of the first signal line.
As can be seen from the foregoing technical solutions, in the present application, after determining a first design parameter of a first signal line and a second design parameter of a second signal line, a method for designing a differential trace is provided, in which a third portion, a fourth portion, and a first portion and a second portion of the second signal line of the first signal line are designed, a distance between the second portion and the fourth portion is greater than a distance between the first portion and the third portion, so that a length of the first signal line is equal to a length of the second signal line, that is, lengths of the first signal line and the second signal line are ensured to be equal in a winding manner, a problem that transmission efficiency is low due to unequal lengths of the first signal line and the second signal line is avoided, and then a width of the first portion of the second signal line and a width of the third portion of the first signal line are determined, and calculating the differential impedance of a third part of the first signal line and a first part of the second signal line, and finally determining the widths of the second part and the fourth part according to the differential impedance of the first part and the third part, the first design parameter and the second design parameter so as to match the differential impedance of the first part and the third part with the differential impedance of the second part and the fourth part, thereby solving the problem of discontinuous impedance of the second signal line caused by winding and avoiding the problem of signal transmission energy loss caused by transmission signal reflection caused by discontinuous impedance.
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In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic view of a winding method for solving the problem of unequal lengths of two signal lines of a differential trace;
fig. 2 is a schematic flow chart of a method for designing a differential trace according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a differential routing according to an embodiment of the present application.
Detailed Description
As described in the background, the differential traces may have different lengths of two differential signal lines due to the arrangement requirement, so that a part of the differential mode energy transmitted by the differential traces is converted into common mode energy, and the transmission efficiency becomes low. In order to solve this problem, referring to fig. 1, the inventors have studied and found that the length of the differential signal lines having a short length due to the arrangement requirement can be increased by winding, but this method may cause the distance D2 between the signal lines in the winding region to become large (as in fig. 1, D1 represents the distance between two signal lines in the normal region), which may cause the impedance of the winding region to be high, which may cause the impedance to be discontinuous. Impedance discontinuities can cause reflections of the transmitted signal, resulting in loss of signal transmission energy. Therefore, a differential wiring structure needs to be designed, so that impedance matching of the differential wiring is ensured while the requirement that two signal lines of the differential wiring are equal in length is met.
In view of this, an embodiment of the present application provides a method for designing a differential trace, including:
determining first design parameters of a first signal line, wherein the first design parameters comprise the length, the thickness and the material dielectric constant of the first signal line;
determining second design parameters of a second signal line, wherein the second design parameters comprise the length, the thickness and a material node constant of the second signal line;
designing a first portion and a second portion of the second signal line, a distance between the second portion and the fourth portion being greater than a distance between the first portion and the third portion, so that a length of the first signal line is equal to a length of the second signal line;
determining a width of a first portion of the second signal line and determining a differential impedance of the first portion and the third portion based on the first design parameter, the second design parameter, and the width of the first portion;
determining widths of the second portion and the fourth portion according to differential impedances of the first portion and the third portion, the first design parameter, and the second design parameter to match the differential impedances of the first portion and the third portion and the second portion and the fourth portion.
After determining a first design parameter of a first signal line and a second design parameter of a second signal line, designing a third part and a fourth part of the first signal line and a first part and a second part of the second signal line, wherein the distance between the second part and the fourth part is greater than the distance between the first part and the third part, so that the length of the first signal line is equal to the length of the second signal line, that is, the lengths of the first signal line and the second signal line are ensured to be equal in a winding manner, avoiding the problem of low transmission efficiency caused by unequal lengths of the first signal line and the second signal line, then determining the width of the first part of the second signal line and the width of the third part of the first signal line, and calculating the differential impedance of the third part of the first signal line and the first part of the second signal line, and finally, determining the widths of the second part and the fourth part according to the differential impedance of the first part and the third part, the first design parameter and the second design parameter so as to match the differential impedance of the first part and the third part with the differential impedance of the second part and the fourth part, solve the problem of discontinuous impedance of a second signal line caused by winding, and avoid the problem of signal transmission energy loss caused by transmission signal reflection caused by discontinuous impedance.
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The embodiment of the present application provides a method for designing a differential routing, as shown in fig. 2, including:
s101: determining first design parameters of a first signal line, wherein the first design parameters comprise the length, the thickness and the material dielectric constant of the first signal line;
s102: determining second design parameters of a second signal line, wherein the second design parameters comprise the length, the thickness and a material node constant of the second signal line;
s103: designing a first portion and a second portion of the second signal line, a distance between the second portion and the fourth portion being greater than a distance between the first portion and the third portion, so that a length of the first signal line is equal to a length of the second signal line;
s104: determining a width of a first portion of the second signal line and determining a differential impedance of the first portion and the third portion based on the first design parameter, the second design parameter, and the width of the first portion;
s105: determining widths of the second portion and the fourth portion according to differential impedances of the first portion and the third portion, the first design parameter, and the second design parameter to match the differential impedances of the first portion and the third portion and the second portion and the fourth portion.
Referring to fig. 3, fig. 3 is a schematic structural diagram of a differential trace designed and obtained according to the differential trace design method, where a second signal line included in the differential trace includes a first portion and a second portion, the second portion is a routing area, and the length of the second portion is increased by a routing manner of the second portion, so that during the arrangement process of the differential trace, situations such as "the trace turns" and the like are avoidedThis causes the second signal line to be shorter than the first signal line. Meanwhile, due to the existence of the winding area, the distance between the second part of the second signal wire and the third part of the first signal wire is larger than the distance between the first part of the second signal wire and the fourth part of the first signal wire, and according to the calculation formula of the differential impedance between the two signal wires: zdiff ═ 2 × Zo (1-0.48 e)-0.96D/H) (ii) a Wherein the content of the first and second substances,
Figure BDA0002717342910000091
zo denotes the impedance of each of the two signal lines, Zdiff denotes the impedance of the signal line, W denotes the width of the signal line, D denotes the distance between the two signal lines, T denotes the thickness of the signal line, Er denotes the dielectric constant of the substrate carrying the signal line, and H denotes the dielectric thickness of the substrate. It can be known that when the pitch increases and other parameters remain unchanged, the differential impedance between the second portion of the second signal line and the fourth portion of the first signal line increases, thereby causing impedance discontinuity of the differential routing, in this embodiment, by separately designing the width of the second portion of the second signal line and the width of the fourth portion of the first signal line, the differential impedance between the second portion of the second signal line and the fourth portion of the first signal line is reduced, thereby satisfying the requirement of impedance continuity of the differential routing.
In fig. 3, reference numeral 10 denotes the first signal line, 11 denotes the third portion, 12 denotes the fourth portion, 20 denotes the second signal line, 21 denotes the first portion, 22 denotes the second portion, D1 denotes a spacing between the third portion of the first signal line and the first portion of the second signal line, and D2 denotes a spacing between the fourth portion of the first signal line and the second portion of the second signal line. W1 denotes a width of the first portion of the second signal line, and W2 denotes a width of the second portion of the second signal line and a width of the fourth portion of the first signal line. As can be readily seen from FIG. 3, W1 is less than W2. Generally, the width of the third portion of the first signal line is equal to the width of the first portion of the second signal line, and both can be the width of the differential trace in the conventional design.
In this embodiment, after determining the first design parameter of the first signal line and the second design parameter of the second signal line, the method for designing the differential trace designs the third portion and the fourth portion of the first signal line and the first portion and the second portion of the second signal line, where the distance between the second portion and the fourth portion is greater than the distance between the first portion and the third portion, so as to make the length of the first signal line equal to the length of the second signal line, i.e. to ensure that the lengths of the first signal line and the second signal line are equal in a winding manner, thereby avoiding the problem of low transmission efficiency caused by unequal lengths of the first signal line and the second signal line, then determines the width of the first portion of the second signal line and the width of the third portion of the first signal line, and calculates the differential impedance between the third portion of the first signal line and the first portion of the second signal line, and finally, determining the widths of the second part and the fourth part according to the differential impedance of the first part and the third part, the first design parameter and the second design parameter so as to match the differential impedance of the first part and the third part with the differential impedance of the second part and the fourth part, solve the problem of discontinuous impedance of a second signal line caused by winding, and avoid the problem of signal transmission energy loss caused by transmission signal reflection caused by discontinuous impedance.
A specific feasible implementation method of each step of the design method for differential routing provided in the embodiment of the present application is described below.
In one embodiment of the present application, the determining a width of the first portion of the second signal line and the determining a differential impedance of the first portion and the third portion according to the first design parameter, the second design parameter, and the width of the first portion includes:
s1041: setting a width of the first portion to be the same as a width of the third portion;
s1042: calculating an impedance of the first signal line according to the first design parameter and a width of the third portion;
s1043: calculating an impedance of the first portion of the second signal line according to the second design parameter and a width of the first portion of the second signal line;
s1044: calculating a differential impedance of the third portion of the first signal line and the first portion of the second signal line from the impedance of the third portion of the first signal line, the impedance of the first portion of the second signal line, and a distance between the third portion of the first signal line and the first portion of the second signal line.
The calculating an impedance of the first portion of the second signal line according to the second design parameter and the width of the first portion of the second signal line includes:
s10431: substituting the second design parameter and the width of the first part of the second signal line into a first preset formula to calculate and obtain the impedance of the first part of the second signal line;
the first preset formula includes:
Figure BDA0002717342910000111
wherein Z is21Representing the impedance of the first part of the second signal line, W21Denotes the width of the first portion of the second signal line, Er denotes the dielectric constant of the material, T2The thickness of the second signal line is indicated, and H indicates the thickness of the substrate carrying the differential signal lines.
The calculating the impedance of the first signal line according to the first design parameter and the width of the third portion includes:
s10421: substituting the first design parameter and the width of the third part into a second preset formula to calculate and obtain the impedance of the first signal line;
the second preset formula includes:
Figure BDA0002717342910000112
wherein Z is1Represents an impedance of a third portion of the first signal line, W1Denotes the width of the third portion of the first signal line, Er denotes the materialDielectric constant, T1The thickness of the third portion of the first signal line is indicated, and H indicates the thickness of the substrate carrying the differential signal lines.
The calculating a differential impedance of the third portion of the first signal line and the first portion of the second signal line from the impedance of the third portion of the first signal line, the impedance of the first portion of the second signal line, and the distance between the third portion of the first signal line and the first portion of the second signal line includes:
s10441: substituting the impedance of the third part of the first signal line, the impedance of the first part of the second signal line and the distance between the third part of the first signal line and the first part of the second signal line into a third preset formula to calculate and obtain the differential impedance of the third part of the first signal line and the first part of the second signal line;
the third preset formula includes:
Figure BDA0002717342910000121
wherein Zdiff represents a differential impedance of the third portion of the first signal line and the first portion of the second signal line, D1Represents a distance between the third portion of the first signal line and the first portion of the second signal line.
The determining widths of the second portion and the fourth portion based on the differential impedance of the first portion and the third portion, the first design parameter, and the second design parameter to match the differential impedance of the first portion and the third portion and the differential impedance of the second portion and the fourth portion comprises:
s1051: substituting the differential impedance of the third part of the first signal line and the first part of the second signal line, the first design parameter and the second design parameter into a fourth preset formula to calculate and obtain the width of the second part of the second signal line;
the fourth preset formula includes:
Figure BDA0002717342910000122
wherein, W22Denotes the width of the second portion of the second signal line and the width of the fourth portion of the first signal line, D2Represents a distance, T, between the second portion of the second signal line and the fourth portion of the first signal line2The thickness of the second signal line is indicated.
The differential trace provided in the embodiments of the present application is described below, and the differential trace described below may be referred to by the design method of the differential trace described above.
Correspondingly, the present application provides a differential routing, referring to fig. 3, including: a first signal line 10 and a second signal line 20; wherein the content of the first and second substances,
the second signal line 20 includes a first portion 21 and a second portion 22, a distance between the first portion 21 of the second signal line 20 and the third portion 11 of the first signal line 10 is a first distance, a distance between the second portion 22 of the second signal line 20 and the fourth portion 12 of the first signal line 10 is a second distance, and the first distance is smaller than the second distance;
the width of the first portion 21 of the second signal line 20 is smaller than the width of the second portion 22 of the second signal line 20, so that the differential impedance of the first portion 21 of the second signal line 20 and the first signal line 10 matches the differential impedance of the second portion 22 of the second signal line 20 and the first signal line 10.
Optionally, the width of the second portion 22 of the second signal line 20 is determined by a fourth preset formula;
the fourth preset formula includes:
Figure BDA0002717342910000131
wherein Er represents the dielectric constant of the material, T2Denotes the thickness of the second signal line 20, H denotes the thickness of the substrate carrying the differential signal lines, W22Denotes the width of the second portion 22 of the second signal line 20 and the width of the fourth portion 12 of the first signal line 10, D2A second portion 22 of the second signal line 20 and a fourth portion of the first signal line 10The distance between the sections 12.
In summary, the present application provides a differential trace and a design method thereof, wherein after determining a first design parameter of a first signal line and a second design parameter of a second signal line, the design method of the differential trace designs a third portion, a fourth portion of the first signal line and a first portion and a second portion of the second signal line, a distance between the second portion and the fourth portion is greater than a distance between the first portion and the third portion, so that a length of the first signal line is equal to a length of the second signal line, that is, the lengths of the first signal line and the second signal line are ensured to be equal in a wire winding manner, thereby avoiding a problem that transmission efficiency is low due to unequal lengths of the first signal line and the second signal line, and then determining a width of the first portion of the second signal line and a width of the third portion of the first signal line, and calculating the differential impedance of a third part of the first signal line and a first part of the second signal line, and finally determining the widths of the second part and the fourth part according to the differential impedance of the first part and the third part, the first design parameter and the second design parameter so as to match the differential impedance of the first part and the third part with the differential impedance of the second part and the fourth part, thereby solving the problem of discontinuous impedance of the second signal line caused by winding and avoiding the problem of signal transmission energy loss caused by transmission signal reflection caused by discontinuous impedance.
Features described in the embodiments in the present specification may be replaced with or combined with each other, each embodiment is described with a focus on differences from other embodiments, and the same and similar portions among the embodiments may be referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. A method for designing a differential trace, comprising:
determining first design parameters of a first signal line, wherein the first design parameters comprise the length, the thickness and the material dielectric constant of the first signal line;
determining second design parameters of a second signal line, wherein the second design parameters comprise the length, the thickness and a material node constant of the second signal line;
designing a first portion and a second portion of the second signal line, a distance between the second portion and the fourth portion being greater than a distance between the first portion and the third portion, so that a length of the first signal line is equal to a length of the second signal line;
designing a third part and a fourth part of the first signal line, wherein the width of the third part is smaller than that of the fourth part;
determining widths of the first portion and the third portion, and determining differential impedances of the first portion and the third portion based on the first design parameter, the second design parameter, and the widths of the first portion and the third portion;
determining widths of the second portion and the fourth portion according to differential impedances of the first portion and the third portion, the first design parameter, and the second design parameter to match the differential impedances of the first portion and the third portion and the second portion and the fourth portion.
2. The method of designing a differential trace according to claim 1, wherein the determining widths of the first portion and the third portion, and determining differential impedance of the first portion and the third portion according to the first design parameter, the second design parameter, and the widths of the first portion and the third portion comprises:
setting a width of the first portion to be the same as a width of the third portion;
calculating an impedance of the first signal line according to the first design parameter and a width of the third portion;
calculating an impedance of the first portion of the second signal line according to the second design parameter and a width of the first portion of the second signal line;
calculating a differential impedance of the third portion of the first signal line and the first portion of the second signal line from the impedance of the third portion of the first signal line, the impedance of the first portion of the second signal line, and a distance between the third portion of the first signal line and the first portion of the second signal line.
3. The method of designing a differential trace according to claim 2, wherein the calculating the impedance of the first portion of the second signal line according to the second design parameter and the width of the first portion of the second signal line includes:
substituting the second design parameter and the width of the first part of the second signal line into a first preset formula to calculate and obtain the impedance of the first part of the second signal line;
the first preset formula includes:
Figure FDA0002717342900000021
wherein Z is21Representing the impedance of the first part of the second signal line, W21Denotes the width of the first portion of the second signal line, Er denotes the dielectric constant of the material, T2The thickness of the second signal line is indicated, and H indicates the thickness of the substrate carrying the differential signal lines.
4. The method of designing a differential trace according to claim 3, wherein the calculating the impedance of the first signal line according to the first design parameter and the width of the third portion includes:
substituting the first design parameter and the width of the third part into a second preset formula to calculate and obtain the impedance of the first signal line;
the second preset formula includes:
Figure FDA0002717342900000022
wherein Z is1Represents an impedance of a third portion of the first signal line, W1Denotes the width of the third portion of the first signal line, Er denotes the dielectric constant of the material, T1The thickness of the third portion of the first signal line is indicated, and H indicates the thickness of the substrate carrying the differential signal lines.
5. The method for designing a differential trace according to claim 4, wherein the calculating the differential impedance of the third portion of the first signal line and the first portion of the second signal line according to the impedance of the third portion of the first signal line, the impedance of the first portion of the second signal line, and the distance between the third portion of the first signal line and the first portion of the second signal line includes:
substituting the impedance of the third part of the first signal line, the impedance of the first part of the second signal line and the distance between the third part of the first signal line and the first part of the second signal line into a third preset formula to calculate and obtain the differential impedance of the third part of the first signal line and the first part of the second signal line;
the third preset formula includes:
Figure FDA0002717342900000031
wherein Zdiff represents a differential impedance of the third portion of the first signal line and the first portion of the second signal line, D1Represents a distance between the third portion of the first signal line and the first portion of the second signal line.
6. The method of designing a differential trace according to claim 5, wherein the determining widths of the second portion and the fourth portion according to the differential impedance of the first portion and the third portion, the first design parameter and the second design parameter so that the differential impedance of the first portion and the third portion and the differential impedance of the second portion and the fourth portion match includes:
substituting the differential impedance of the third part of the first signal line and the first part of the second signal line, the first design parameter and the second design parameter into a fourth preset formula to calculate and obtain the width of the second part of the second signal line;
the fourth preset formula includes:
Figure FDA0002717342900000032
wherein, W22Denotes the width of the second portion of the second signal line and the width of the fourth portion of the first signal line, D2Represents a distance, T, between the second portion of the second signal line and the fourth portion of the first signal line2The thickness of the second signal line is indicated.
7. A differential trace, comprising: a first signal line and a second signal line; wherein the content of the first and second substances,
the second signal line comprises a first part and a second part, the distance between the first part of the second signal line and the third part of the first signal line is a first distance, the distance between the second part of the second signal line and the fourth part of the first signal line is a second distance, and the first distance is smaller than the second distance;
the first signal line includes a third portion and a fourth portion, a width of the third portion being smaller than a width of the fourth portion; and a width of the first portion of the second signal line is smaller than a width of the second portion of the second signal line to match a differential impedance of the first portion and the third portion with a differential impedance of the second portion and the fourth portion.
8. The differential trace of claim 1, wherein a width of the second portion of the second signal line is determined by a fourth predetermined formula;
the fourth preset formula includes:
Figure FDA0002717342900000041
wherein Er represents the dielectric constant of the material, T2Denotes the thickness of the second signal line, H denotes the thickness of the substrate carrying the differential signal lines, W22Denotes the width of the second portion of the second signal line and the width of the fourth portion of the first signal line, D2Represents a distance between the second portion of the second signal line and the fourth portion of the first signal line.
CN202011079146.1A 2020-10-10 2020-10-10 Differential routing and design method thereof Pending CN112004313A (en)

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US20200092986A1 (en) * 2017-11-29 2020-03-19 Dell Products L.P. Differential trace pair system
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Publication number Priority date Publication date Assignee Title
CN104039076A (en) * 2014-06-17 2014-09-10 浪潮(北京)电子信息产业有限公司 Wire wrapping method and system for reducing difference circuit impedance mismatch degree
CN104333973A (en) * 2014-11-11 2015-02-04 浪潮电子信息产业股份有限公司 Impedance optimization design method aiming at 3W2S winding compensation
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