CN117744582A - Method for accurately simulating TDR impedance of transmission line - Google Patents
Method for accurately simulating TDR impedance of transmission line Download PDFInfo
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- CN117744582A CN117744582A CN202311788600.4A CN202311788600A CN117744582A CN 117744582 A CN117744582 A CN 117744582A CN 202311788600 A CN202311788600 A CN 202311788600A CN 117744582 A CN117744582 A CN 117744582A
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- 230000005540 biological transmission Effects 0.000 title claims abstract description 39
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000004088 simulation Methods 0.000 claims abstract description 23
- 239000006185 dispersion Substances 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000003292 glue Substances 0.000 claims description 3
- 238000012360 testing method Methods 0.000 abstract description 3
- 238000005259 measurement Methods 0.000 description 5
- 238000007796 conventional method Methods 0.000 description 2
- 238000002310 reflectometry Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
Abstract
The invention relates to a method for accurately simulating the TDR impedance of a transmission line, which comprises the steps of inputting a plurality of dielectric constant values under different frequencies into impedance calculation software, and obtaining a fluctuated TDR impedance curve of the transmission line through simulation; the method specifically comprises the following steps: step 1, establishing a corresponding relation between frequency and dielectric constant; step 2, inputting the corresponding relation between the frequency and the dielectric constant into impedance calculation software; and step 3, automatically acquiring corresponding dielectric constant values at different frequencies by impedance calculation software, and simulating a TDR impedance curve. According to the invention, different dielectric constant values under different frequencies are input into the impedance calculation software, so that the fluctuation transmission line TDR impedance curve is obtained through simulation, and compared with the traditional single-point dielectric constant value input, the impedance condition of the test of the laminated actual plate can be obtained, thereby improving the precision of simulating and predicting the transmission line TDR impedance.
Description
Technical Field
The invention relates to the technical field of electronic circuit simulation, in particular to a method for accurately simulating the TDR impedance of a transmission line.
Background
Printed circuit boards (Printed Circuit Board, PCB boards), also known as printed circuit boards, are an important component of the physical support of electronic products and signal transmission, with transmission lines on the PCB boards being a major component.
TDR (Time Domain Reflectometry), known as time domain reflectometry, is the use of reflections of a signal to measure the extent of impedance change in a transmission line. For engineering application, how to accurately simulate and obtain the TDR impedance of the transmission line has important meaning for predicting the performance of the transmission line.
In the conventional simulation, when the designer uses the impedance software to calculate the impedance, the designer selects the dielectric constant value at one frequency to calculate, and uses a sheet material with medium loss, a Prepreg (PP, prepreg) model 1078 to describe the dielectric constant value, and the designer searches the datasheet (data manual) to obtain the following table:
for example, 3.65 of the dielectric constants at a frequency of 1GHz are selected. Substituting the impedance calculation software can calculate that the impedance is close to 50 ohms under a specific line width.
However, through the data manual, it can be seen that the dielectric constant (DK) varies with frequency, and in the conventional method, a single dielectric constant value is used for inputting impedance software for calculation, so that a simulation result is always different from the practical application; in addition, if the dielectric constant value changes greatly under different frequencies, the theoretical impedance value obtained by software simulation under a single dielectric constant can be further different from the actual condition, so that the simulation structure is inaccurate.
The problems are worth solving.
Disclosure of Invention
In order to solve the problems that the existing transmission line TDR impedance simulation method adopts a single dielectric constant, the obtained impedance theoretical value is inconsistent with the actual situation, and the simulation structure is inaccurate, the invention provides a method for accurately simulating the transmission line TDR impedance.
The technical scheme of the invention is as follows:
a method for accurately simulating the TDR impedance of a transmission line includes inputting multiple dielectric constant values at different frequencies into impedance calculation software, and simulating to obtain a fluctuated TDR impedance curve of the transmission line.
The invention according to the above scheme comprises the following steps:
step 1, establishing a corresponding relation between frequency and dielectric constant;
step 2, inputting the corresponding relation between the frequency and the dielectric constant into impedance calculation software;
and step 3, automatically acquiring corresponding dielectric constant values at different frequencies by impedance calculation software, and simulating a TDR impedance curve.
According to the present invention of the above aspect, the step 1 includes the steps of:
step 101, inquiring a dielectric constant value corresponding to each frequency in a data manual;
102, establishing a frequency and dielectric constant dispersion curve by taking the frequency as an X axis and the dielectric constant as a Y axis;
step 103, calculating the midpoints of every two adjacent discrete points;
104, generating a smooth curve of frequency and dielectric constant;
step 105, a frequency and dielectric constant correspondence file is derived.
According to the present invention of the above aspect, the step 101 includes the steps of:
step A, determining the PP model of a plate;
step B, determining the thickness and the glue content of the plate;
and C, indexing a plurality of dielectric constant values in the same column according to the PP model, the thickness and the gel content.
According to the invention of the scheme, the PP model of the plate is 1078; the thickness of the plate was 3.06mil and the gel content was 68%.
According to the present invention of the above scheme, in the step C, obtaining different dielectric constants at different frequencies includes: the frequency is 1MHz, the dielectric constant is 3.66, the frequency is 1GHz, the dielectric constant is 3.65, the frequency is 2GHz, the dielectric constant is 3.60, the frequency is 5GHz, the dielectric constant is 3.55, the frequency is 10GHz, and the dielectric constant is 3.45.
According to the present invention of the above aspect, the step 2 includes the steps of:
step 201, opening a parameter setting interface of impedance calculation software;
step 202, importing a frequency and dielectric constant corresponding relation file.
According to the invention, the simulated TDR impedance curve is compared with the actually measured TDR impedance curve, and the accuracy of the simulation result is verified.
The invention according to the above scheme comprises the following steps:
step 401, determining the specification of the plate according to the parameters selected by simulation;
step 402, setting a transmission line on a plate, and acquiring an actually measured TDR impedance curve of the transmission line by using a TDR measuring instrument;
step 403, comparing the simulated TDR impedance curve with the measured TDR impedance curve.
The invention according to the scheme has the beneficial effects that:
according to the invention, different dielectric constant values under different frequencies are input into the impedance calculation software, so that the fluctuation transmission line TDR impedance curve is obtained through simulation, and compared with the traditional single-point dielectric constant value input, the impedance condition of the test of the laminated actual plate can be obtained, thereby improving the precision of simulating and predicting the transmission line TDR impedance.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a plot of frequency versus dielectric constant for the present invention;
FIG. 3 is a TDR impedance simulation curve of the present invention;
FIG. 4 is a simulation plot of measured TDR impedance;
fig. 5 is a TDR impedance simulation curve of the prior art.
Detailed Description
For a better understanding of the objects, technical solutions and technical effects of the present invention, the present invention will be further explained below with reference to the drawings and examples. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, it is stated that the embodiments described below are only for explaining the present invention and are not intended to limit the present invention.
It should be noted that the terms "first," "second," "third," "fourth," and "fifth" are used merely for descriptive purposes and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features. The meaning of "a plurality of" is two or more, unless specifically defined otherwise.
As shown in FIG. 1, in a method for accurately simulating the TDR impedance of a transmission line, a plurality of dielectric constant values at different frequencies are input into impedance calculation software, and a fluctuating TDR impedance curve of the transmission line is obtained through simulation.
Before the dielectric constant value is input into the impedance calculation software, step 1: establishing a frequency and dielectric constant correspondence, comprising the following steps:
step 101, inquiring a dielectric constant value corresponding to each frequency in a data manual;
the required board PP model 1078 is found in the data manual, part of the table:
and selecting one line of data with the gel content of 68%, and obtaining the frequency and the corresponding dielectric constant, wherein the data comprises:
the frequency of 1MHz corresponds to a dielectric constant value of 3.66,
the frequency of 1GHz corresponds to a dielectric constant value of 3.65,
the frequency of 2GHz corresponds to a dielectric constant value of 3.60,
the frequency of 5GHz corresponds to a dielectric constant value of 3.55,
the dielectric constant value corresponding to a frequency of 10GHz is 3.45.
102, establishing a frequency and dielectric constant dispersion curve by taking the frequency as an X axis and the dielectric constant as a Y axis;
according to the correspondence, several discrete points (x1=1 mhz, y1=3.66), (x2=1 ghz, y2=3.65), (x3=2 ghz, y3=3.60), (x4=5 ghz, y4=3.55), (x5=10 ghz, y5=3.45) can be obtained; frequency and dielectric constant dispersion curves are plotted.
Step 103, calculating the midpoints of every two adjacent discrete points;
the midpoints of the first discrete point (x1=1 mhz, y1=3.66) and the second discrete point (x2=1 ghz, y2=3.65) are calculated, with: (x, y) = ((x1+x2)/2, (y1+y2)/2) = (500.5 mhz, 3.655); similarly, the midpoints of the second discrete point (x2=1ghz, y2=3.65) and the third discrete point (x3=2ghz, y3=3.60) are calculated, the midpoints of the third discrete point (x3=2ghz, y3=3.60) and the fourth discrete point (x4=5ghz, y4=3.55) are calculated, and the midpoints of the fourth discrete point (x4=5ghz, y4=3.55) and the fifth discrete point (x5=10 ghz, y5=3.45) are calculated.
104, producing a smooth curve of frequency and dielectric constant;
step 103 is repeated, and the midpoints of two adjacent discrete points are further calculated until a smooth curve meeting the requirement is drawn, see fig. 2.
Step 105, a frequency and dielectric constant correspondence file is derived.
In the present invention, the inputting of a plurality of dielectric constant values at different frequencies in the impedance calculation software includes the steps of 2: the frequency and dielectric constant corresponding relation is input into impedance calculation software, which comprises the following steps:
step 201, opening a parameter setting interface of impedance calculation software;
step 202, importing the frequency and dielectric constant correspondence file obtained in step 105.
In the invention, the simulation obtains a fluctuating transmission line TDR impedance curve, which comprises the following steps: the impedance calculation software automatically obtains corresponding dielectric constant values at different frequencies, and a TDR impedance curve is simulated.
The impedance software obtains the corresponding dielectric constant value at each frequency according to the data recorded in the imported file, simulates different impedance values according to each dielectric constant value of different frequency bands in the frequency domain, and feeds back the impedance values to the TDR impedance in the time domain, so that impedance fluctuation is formed, and please refer to FIG. 3.
Finally, the simulation result of the method can be compared with the actual measurement result to verify whether the method can accurately reflect the actual measurement TDR impedance curve. Specifically, TRD actual measurement is performed on a board provided with a transmission line to obtain an actual measurement TDR impedance curve, please refer to fig. 4, and the dashed box part shown in the drawing is to examine the impedance situation in the frequency band, so that the actual measured transmission line impedance fluctuates, and the impedance situation of the dashed box part is similar to the simulation result of the method, so that the method can be verified to be in line with the actual situation. While the TDR impedance modeled and simulated by the conventional method is ideal, the simulation result is nearly linear, please refer to fig. 5, and the actual measurement result cannot be accurately reflected.
In summary, according to the invention, by inputting different dielectric constant values under different frequencies into the impedance calculation software, the fluctuated transmission line TDR impedance curve is obtained through simulation, and compared with the traditional single-point dielectric constant value input, the impedance condition of the test of the bonding actual plate can be obtained, so that the precision of simulating and predicting the transmission line TDR impedance is improved.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. A method for accurately simulating the TDR impedance of a transmission line is characterized in that a plurality of dielectric constant values under different frequencies are input into impedance calculation software, and a fluctuating TDR impedance curve of the transmission line is obtained through simulation.
2. The method of accurately simulating transmission line TDR impedance of claim 1, comprising the steps of:
step 1, establishing a corresponding relation between frequency and dielectric constant;
step 2, inputting the corresponding relation between the frequency and the dielectric constant into impedance calculation software;
and step 3, automatically acquiring corresponding dielectric constant values at different frequencies by impedance calculation software, and simulating a TDR impedance curve.
3. The method of accurately simulating TDR impedance of a transmission line according to claim 2, wherein the step 1 comprises the steps of:
step 101, inquiring a dielectric constant value corresponding to each frequency in a data manual;
102, establishing a frequency and dielectric constant dispersion curve by taking the frequency as an X axis and the dielectric constant as a Y axis;
step 103, calculating the midpoints of every two adjacent discrete points;
104, generating a smooth curve of frequency and dielectric constant;
step 105, a frequency and dielectric constant correspondence file is derived.
4. A method of accurately simulating the TDR impedance of a transmission line according to claim 3, wherein said step 101 comprises the steps of:
step A, determining the PP model of a plate;
step B, determining the thickness and the glue content of the plate;
and C, indexing a plurality of dielectric constant values in the same column according to the PP model, the thickness and the gel content.
5. The method of accurately simulating TDR impedance of a transmission line of claim 4, wherein the sheet material determined in step a has a PP model 1078 and a sheet material thickness of 3.06mil.
6. The method of accurately simulating transmission line TDR impedance of claim 5, wherein the glue content of the sheet material is 68%.
7. The method for precisely simulating TDR impedance of a transmission line according to claim 6, wherein in the step C, different dielectric constants at different frequencies are obtained, comprising: the frequency is 1MHz, the dielectric constant is 3.66, the frequency is 1GHz, the dielectric constant is 3.65, the frequency is 2GHz, the dielectric constant is 3.60, the frequency is 5GHz, the dielectric constant is 3.55, the frequency is 10GHz, and the dielectric constant is 3.45.
8. The method of accurately simulating TDR impedance of a transmission line according to claim 2, wherein the step 2 comprises the steps of:
step 201, opening a parameter setting interface of impedance calculation software;
step 202, importing a frequency and dielectric constant corresponding relation file.
9. The method for accurately simulating the TDR impedance of a transmission line according to claim 1 or 2, wherein the simulated TDR impedance curve is compared with the measured TDR impedance curve, and the accuracy of the simulation result is verified.
10. The method of accurately simulating transmission line TDR impedance of claim 9, comprising the steps of:
step 401, determining the specification of the plate according to the parameters selected by simulation;
step 402, setting a transmission line on a plate, and acquiring an actually measured TDR impedance curve of the transmission line by using a TDR measuring instrument;
step 403, comparing the simulated TDR impedance curve with the measured TDR impedance curve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311788600.4A CN117744582A (en) | 2023-12-22 | 2023-12-22 | Method for accurately simulating TDR impedance of transmission line |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311788600.4A CN117744582A (en) | 2023-12-22 | 2023-12-22 | Method for accurately simulating TDR impedance of transmission line |
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| CN117744582A true CN117744582A (en) | 2024-03-22 |
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| CN202311788600.4A Pending CN117744582A (en) | 2023-12-22 | 2023-12-22 | Method for accurately simulating TDR impedance of transmission line |
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- 2023-12-22 CN CN202311788600.4A patent/CN117744582A/en active Pending
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