CN-116960593-B - T-shaped microstrip line capable of inhibiting far-end crosstalk aiming at specific frequency and design method thereof

Abstract

A T-shaped microstrip line capable of inhibiting far-end crosstalk aiming at specific frequency and a design method thereof belong to the technical field of electrical equipment and electrical engineering and mainly comprise the following steps of 1) starting with parallel uniform microstrip lines, calculating parameters of the parallel microstrip lines of a PCB to obtain line width, line length and line thickness of high-density layout of the PCB, 2) providing a novel microstrip line structure, namely a T-shaped microstrip line, adding T-shaped bulges at the inner sides of the parallel uniform microstrip lines, analyzing influences of different structural parameters on far-end crosstalk from frequency domain angles, and 3) optimizing the structural parameters aiming at specific frequency, obtaining an optimal T-shaped microstrip line through time domain and frequency domain simulation, and comparing other types of microstrip lines to enhance crosstalk inhibition effects. The invention has the advantages of low far-end crosstalk at specific frequency, clear design method and high wiring density.

Inventors

• DONG WEIJIE
• DUAN HANQING
• XIE YONGPING
• REN BINGXIN

Assignees

• 大连理工大学

Dates

Publication Date

20260512

Application Date

20230627

Claims (5)

1. 1. The design method of the T-shaped microstrip line is characterized by comprising the following steps of: step 1, setting the characteristic impedance and the line width of a parallel microstrip line of a PCB; firstly, selecting a PCB board made of copper-clad material, then setting microstrip line thickness according to the characteristic impedance of parallel microstrip lines Determining the distance between the microstrip line and the stratum; Step 2, determining the length l of two parallel uniform microstrip lines according to the need, adding T-shaped bulges uniformly staggered on the inner sides of the two microstrip lines, wherein the structural parameters of the T-shaped bulges are the width a of a vertical structure, the length b of a transverse structure, the length D of a T-shaped pair and the logarithm n, so as to form a novel T-shaped microstrip line, and controlling the capacitance of the microstrip line while keeping the high-density layout of a PCB (printed circuit board), wherein the length D of the T-shaped pair refers to the distance between the same side of the long sides of two adjacent T-shaped bulges on the same microstrip line, and the length comprises two relatively distributed T-shaped bulges on the inner sides of the two microstrip lines; The values of n and D are constrained with each other, the value of D with obvious crosstalk inhibition effect is 8-13 w, wherein w is the line width of a single microstrip line, D is selected in the range, and then n is determined by l and D; Step 4, applying ANSYS HFSS simulation software to obtain a far-end crosstalk coefficient S 41 in a frequency band covering specific frequencies in a simulation manner, wherein the far-end crosstalk coefficient S 41 is used as an index for measuring signal transmission performance and crosstalk inhibition effect, the S 41 has crosstalk valley frequency and is related to T-shaped convex structure parameters, and the method comprises the following specific steps: (a) Taking D and n selected in the step 3, scanning a from 1-3 w, scanning b from a to (0.5D-w), recording a curve of the far-end crosstalk coefficient S 41 along with the frequency change when a and b change, simultaneously recording the far-end crosstalk coefficient S 41 at a specific frequency in the curve, and recording the structural parameters of T-shaped bulges with crosstalk valleys at a plurality of groups of specific frequencies; (b) Changing the magnitudes of D and n in step3, the value of n will also change after changing the selected value of D, so there are a plurality of combinations of n, D, repeating step (a); And 5, comprehensively considering all indexes of the combinations of the n, D, a, b obtained in the step 4, and selecting the optimal combination.
2. 2. The method according to claim 1, wherein in the step 5, the preferential index sequentially includes S 41 < -35dB, (b×n)/l at a specific frequency, the structural parameters are preliminarily screened under the preferential index, then time domain simulation is performed, an eye diagram is obtained by using ADS simulation software, and the combination of the structural parameters with the best eye diagram index is selected as the best T-type microstrip line structure at the specific frequency.
3. 3. The method of claim 1, wherein the characteristic impedance of the parallel microstrip line in step 1 The calculation formula of (2) is as follows: (1) In the formula, Indicating the relative dielectric constant of the PCB board, Representing the distance between the microstrip line and the ground layer, Represents the line width of the microstrip line, The thickness of the microstrip line is shown, and the characteristic impedance of the parallel microstrip line is 50 omega.
4. 4. The T-shaped microstrip line is characterized in that the T-shaped microstrip line is obtained by adopting the design method of any one of claims 1-3, the line width w is the minimum process line width, the line spacing is 3w, and T-shaped bulges are added on the inner sides of the parallel and uniform microstrip lines so as to keep high density.
5. 5. The T-shaped microstrip line according to claim 4, wherein the T-shaped projections are arranged on two inner sides of the T-shaped microstrip line at equal intervals, and the heights of the T-shaped projections on both sides are the same.

Description

T-shaped microstrip line capable of inhibiting far-end crosstalk aiming at specific frequency and design method thereof Technical Field The invention relates to a T-shaped microstrip line capable of inhibiting far-end crosstalk aiming at specific frequency and a design method thereof, belonging to the technical field of electrical equipment and electrical engineering. Background With the continuous development of modern digital circuits and communication technologies, electronic products are continuously advanced towards miniaturization and high-frequency trend, and clock frequencies up to GHz, picosecond rising edges and high-density PCB layout lead to circuit design to face more and more serious signal integrity problems, crosstalk is one of the key problems affecting signal quality, and can cause data transmission disorder and even system paralysis. Therefore, how to realize high density of PCB while suppressing crosstalk so that high-speed high-frequency signals are completely transmitted is a problem to be solved. Patent CN116017843a proposes a PCB anti-crosstalk wiring structure, which is a multi-layer structure, a plurality of signal wires are arranged on a signal layer in the multi-layer structure, wherein a plurality of sections of first protection ground wires which are isolated from each other are arranged between two adjacent signal wires in the plurality of signal wires. However, when using the ground wire, it is necessary to ensure that the via is well grounded, and the density of the vias is sufficient, and when the via pitch is too large, resonance is easily generated between the wires, so that the crosstalk between the wires becomes very complex. Patent US11369020B2 proposes a stacked multilayer transmission line comprising at least one pair of conductive tracks, each having electrically coupled thereto a number of conductive protrusions placed in one or more spatial layers separate from the conductive tracks. But the added conductive protrusions occupy the upper space of the wire trace, increasing the manufacturing cost. The Intel corporation 2015 proposes Tabbed routing that it has been used in ball grid array package leads and high density data signal traces to reduce the trace impedance and increase the mutual capacitance between the traces to reduce far-end crosstalk. But it does not disclose a specific design method. Aiming at the problems existing in the prior art, the invention provides a novel T-shaped microstrip line suitable for a high-frequency high-density PCB, and provides a design method of T-shaped microstrip line parameters capable of inhibiting far-end crosstalk aiming at specific frequencies, which has the advantages of low crosstalk, definite method and capability of improving wiring density. Disclosure of Invention Aiming at the problem of far-end crosstalk of a fifth-generation double-rate synchronous dynamic random access memory (DDR 5) high-speed high-density single-ended microstrip line, the invention provides a T-shaped microstrip line, T-shaped bulges are added on the inner sides of parallel uniform microstrip lines, structural parameter optimization design is carried out aiming at specific frequency, an optimal T-shaped structure is obtained, and the far-end crosstalk is reduced to the minimum. In order to achieve the aim of the invention and solve the problems existing in the prior art, the invention adopts the following technical scheme: A novel T-shaped microstrip line capable of inhibiting far-end crosstalk can inhibit far-end crosstalk aiming at specific frequency, the T-shaped microstrip line takes a line width w as a minimum process line width and a line interval as 3w, and T-shaped bulges are added on the inner sides of the parallel and uniform microstrip lines so as to keep high density. Furthermore, T-shaped bulges are arranged on the two inner sides of the microstrip line at equal intervals, and the heights of the T-shaped bulges on the two sides are the same. A design method of a novel T-shaped microstrip line capable of inhibiting far-end crosstalk can inhibit far-end crosstalk aiming at specific frequency, and comprises the following steps: Step 1, setting the characteristic impedance and the line width of the parallel microstrip line of the PCB Firstly, selecting a PCB plate made of copper-clad material (high-frequency plate such as PTFE material), setting microstrip line thickness, and determining the distance between the microstrip line and the stratum according to a calculation formula (1) of the characteristic impedance Z 0 of the parallel microstrip line. Wherein epsilon r represents the relative dielectric constant of the PCB, h represents the distance between the microstrip line and the stratum, w represents the line width of the microstrip line, t represents the thickness of the microstrip line, and the characteristic impedance of the parallel microstrip line is 50 omega. And 2, determining the lengths l of two parallel uniform microstrip l