JP3212735B2 - CAD system for LSI and printed wiring boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CAD system for an LSI / printed wiring board, and more particularly to a CAD system for an LSI / printed wiring board which can easily perform a noise check on the LSI / printed wiring board. It is about.

[0002]

2. Description of the Related Art With the recent miniaturization and speeding-up of computers, noise analysis of LSIs and printed wiring boards used therein has become the most important issue. For this reason, various simulation apparatuses are provided, but analysis using the simulation apparatus requires a long processing time. For this reason, a technique for obtaining an effective processing result in a short time is required.

A conventional C without using a simulation device
A method of analyzing cross-stroke noise in an AD system is to determine in advance a maximum parallel length that is not affected by noise even when wiring is adjacent and parallel, and check the line length, that is, check noise based on the maximum parallel length. Was something.

[0004]

However, the above checking method does not actually check the direction of the signal flowing through the adjacent net, so that the cross stroke
Wiring not affected by noise was sometimes judged to be dangerous. In particular, when the wiring density is increased and the checking is strict, the wiring that is not actually affected by noise is often judged to be dangerous, and there has been a problem that accurate checking becomes difficult.

On the other hand, when performing a noise analysis using the above-described simulation apparatus, it takes a long time to design a wiring, and even if it is understood from the result of the noise analysis that noise is likely to occur, how to correct the wiring pattern there is also a problem, such as do not know how to Re Bayoi of. The present invention has been invented in order to improve the above-mentioned disadvantages of the prior art. By checking the propagation direction of a signal flowing in an adjacent net, a net in which cross-stroke noise is easily ridden can be shortened. It is another object of the present invention to provide a CAD system for an LSI and a printed wiring board which can accurately detect the wiring and how to correct which wiring.

[0006]

FIG. 1 is a diagram illustrating the principle of the present invention. In FIG. 1, reference numeral 1 denotes a library in which the parallel maximum line length of a line and an influence range of noise according to the signal intensity are stored, 2 is a net information library in which net information of an LSI / printed wiring board is stored, and 3 is a CAD system. ,
3a reads net information such as a wiring pattern and a signal propagation direction of a line from a net information library, displays them on the display device 4, and calculates a parallel line length of a line of interest.
The parallel line length checking means 4 for checking the parallel line length obtained by the net information checking means 3a with reference to the parallel maximum line length stored in the storage device 4 is a display device .

In order to solve the above-mentioned problems, the invention of claim 1 of the present invention, as shown in FIG. 1, uses an LSI LSI based on a wiring pattern of an LSI printed wiring board and net information such as a signal propagation direction in each line. Noise on printed wiring boards
In the LSI / printed wiring board CAD system to be checked, the display device 4, the net information library 2 storing the wiring pattern of each line and the signal propagation direction in each line, and the net to be checked are input.
When, and checked from the net information library 2
For made net, reading and wiring pattern, a signal propagation direction of the net information lines, be checked Ne
And a net information investigation means 3a for displaying the signal propagation direction of the packet on the display device.

According to a second aspect of the present invention, in the first aspect, the signal propagation direction of the interlayer line is displayed by the net information checking means 3a.
The invention of claim 3 of the present invention is the invention of claim 1,
The direction of signal propagation in the via is displayed by the net information checking means 3a. According to a fourth aspect of the present invention, there is provided a CAD system for an LSI / printed wiring board which performs a noise check on the LSI / printed wiring board based on a wiring pattern of the LSI printed wiring board and net information such as a signal propagation direction in each line. , A display device 4, a net information library 2 storing a wiring pattern of each line, a signal propagation direction and a signal strength in each line, a library 1 storing a noise influence range corresponding to the line signal strength, Information Library 2
More, reading and wiring patterns, the information in the signal propagation direction and the signal intensity of the line, also reads the influence range of noise according to the signal strength from the library, attention Rye
The signal strength of the line and the signal strength of the line
Influence range of noise according to signal strength read from library
From the box, find the affected range of the noise of the line
Find the signal propagation direction of the line within the
Line and other lines within the noise influence range of the line.
The signal propagation direction in is provided with a a net information checking means for displaying on the display device.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the signal propagation direction is selected by the net information investigating means 3a among the line of interest and the other interlayer lines within the noise influence range of the line. Indicates an interlayer line in the reverse direction. The invention according to claim 6 of the present invention is the invention according to claim 4, wherein the network information investigation means
The stage 3a displays vias of which the signal propagation direction is the reverse direction among the vias of interest and other vias within the noise influence range of the via.

According to a seventh aspect of the present invention, there is provided an LSI / printed wiring board for performing a noise check on the LSI / printed wiring board based on a wiring pattern of the LSI printed wiring board and net information such as a signal propagation direction in each line. CA
In the D system, the display device 4, the net information library 2 storing the wiring pattern of each line, the signal propagation direction and the signal strength of each line, and the influence of noise.
Not the maximum parallel line length, the library 1 that stores the influence range of noise according to the line signal strength, and the wiring pattern from the net information library 2, the signal propagation direction of the line
And reading the net information of the signal strength, of the focused line
Determine the signal strength and compare the signal strength of the line with the library
Range of noise depending on the signal strength read from the
Et al., Asked the extent of influence of the noise of the focused line, it is noted
Signal propagation on lines that are within the noise range of the affected line
Other lines of the line of interest depending on the direction and distance between lines
Net information survey means for calculating and recording the parallel line length with
A parallel line length check means for checking the parallel line length of each line obtained by the net information checking means with reference to the maximum parallel line length stored in the library 1 is provided.

[0011]

In FIG. 1, the influence range of the noise on the parallel maximum line length and the signal intensity of the line is determined and registered in the library 1. Net information investigation means 3 of CAD system 3
a reads out net information such as a wiring pattern and a signal propagation direction of a line from the net information library 2 and displays them on the display device 4.

Further, the net information investigating means 3a obtains the signal strength of the line of interest from the net information of the net information library 2, and obtains the influence range of the noise by the signal strength of the line based on the information stored in the library 1. The signal propagation directions of the lines within the influence range are obtained and displayed on the display device 4. Then, based on the propagation direction of the signal of the line within the influence range of the noise of the line of interest and the distance between the lines, the parallel line length with the other line of the line of interest is calculated and recorded, and the above processing is completely performed. This is performed for the lines, and the parallel line lengths of all the lines are obtained.

The parallel line length checking means 3b is a library 1
The parallel line length of each line obtained by the net information checking means 3a is checked with reference to the maximum parallel line length stored in the. According to the first to third aspects of the present invention, the signal propagation direction of each line, interlayer line, or via of the LSI printed wiring board can be displayed as described above. Based on the result, it is possible to easily understand the arrangement of each line including the signal propagation direction and which wiring pattern is dangerous, and it is possible to design an LSI / printed wiring board in consideration of the influence of noise.

In the invention of claims 4 to 6 of the present invention, the line or via of interest and the other line, other interlayer line or via within the noise influence range of the line or via are selected. Since the signal propagation direction can be displayed in the opposite direction, the designer can select from among other lines, other interlayer lines, and vias within the noise influence range.
In particular, it is possible to easily grasp a line in the reverse direction which has a great influence on noise, and it is possible to design an LSI / printed wiring board in consideration of the influence of noise as in the first to third aspects of the present invention. .

In the invention of claim 7 of the present invention, LS
Since the parallel wiring length of each line can be obtained in consideration of the signal propagation direction of the I-printed wiring board, wiring that is not affected by noise is not determined to be dangerous, and an accurate noise check can be performed. Also, it is possible to easily grasp which wiring pattern is dangerous.

[0016]

FIG. 2 is a flowchart showing an embodiment of the present invention. In the figure, reference numeral 11 denotes a library, which stores a maximum parallel line length which is not affected by noise and a noise influence range for each signal strength (voltage) of the net. Reference numeral 12 denotes a net information library which stores net information of a printed wiring board to be checked for noise. Reference numeral 13 denotes a display device for displaying net information.

FIG. 3 is a diagram showing an example of a net on a printed wiring board. In the figure, the net numbers 300, 10
Three signal lines of 0,500 are shown. As shown in the figure, the signal strength of the net number 300 is 3V, the signal strength of the net number 100 is 5V, and the net number of 50 is 50.
The signal strength of 0 is 3V. FIG. 1 shows a multi-layer printed wiring board, not shown, but layers of each net are connected via vias (VAI: holes provided in the printed wiring board).

Next, an embodiment of the present invention will be described with reference to the flowchart of FIG. 2 and the net of the printed wiring board of FIG. In step S1 in FIG. 2, the maximum parallel line length which is not affected by noise and the noise influence range for each signal strength (voltage) of the net are determined and registered in the library 11.

In step S2, a net to be checked is input. For example, in the example of FIG. 3, a net number 100 is input. In step S3, information of a net to be checked is obtained from the net information library 12. In the example of FIG. 3, information about the net with the net number 100, for example, information such as the signal propagation direction and the signal strength is obtained.

In step S4, the library 11 is searched based on the signal strength of the net to be checked to obtain a noise influence range, and in step S5,
Search for nets within the noise range. For example, for the net number 100 in FIG.
Since it is V, the influence range of the noise of the net whose signal strength is 5 V is obtained from the library 11, and the net within the influence range is searched. As a result, for example, as shown in FIG. 3, the nets with net numbers 300 and 500 are searched.

The above search results are displayed on the display device 13 of the CAD system, and the designer, based on the display results,
It is possible to grasp the signal propagation direction in the same plane, between layers, and vias, a net within the influence range of noise, and the like. Next, in step S6, the parallel line length between the net to be checked and the net within its influence range is determined. This parallel line length is obtained as follows.

For example, if the net number 100 in FIG. 3 is a net to be checked, and the nets within the influence range are the net number 300 and the net number 500, first,
From the net information stored in the net information library 12, the parallel line length L1-3 between the net of the net number 100 and the net of the net number 300, its net interval S1-3, and its signal propagation direction are the same or opposite. Or get.

Next, the net of the net number 100 and the net number 30 are obtained from the following equation from the coefficient a determined by the obtained net interval S1-3 and the coefficient b determined by the signal propagation direction.
The converted parallel length L'1-3 between the nets of 0 is obtained. L′ 1−3 = a × b × L1−3 Here, the coefficient a is a coefficient that decreases as the net interval S1-3 increases, and the coefficient b is a coefficient when the signal propagation direction is the opposite direction. Where b1 is the coefficient and b2 is the coefficient when the signal propagation direction is the same, then b1> b2 (the effect of noise is greater when the signal propagation direction is the opposite direction). Based on the net information stored in the information library 12, the parallel line length L1-5 between the net with the net number 100 and the net with the net number 500, the net interval S1-5, and whether the signal propagation direction is the same or opposite. Get.

Next, the converted parallel length L between the net of the net number 100 and the net of the net number 500 is obtained from the coefficient a 'determined by the obtained net interval S1-5 and the coefficient b' determined by the signal propagation direction by the following equation. Ask for '1-5. L′ 1−5 = a ′ × b ′ × L1−5 On the other hand, a table is prepared in which the sum of the converted parallel lengths of the respective net numbers is prepared, and the converted parallel length L′ 1− obtained as described above is prepared. 3, L'1-5 is the net number 30 in the above table
Write in the column of 0 and net number 500.

In step S7, the processing from step S2 to step S6 described above is repeated, the converted parallel length is obtained for each net in the same manner as described above, and the obtained converted parallel length is used as the converted parallel length in the column of each net in the above table. Add up. When the processing has been performed for all nets of the printed wiring board as described above, the maximum parallel line length is searched in step S8, and a net exceeding the maximum parallel line length registered in the library 11 is obtained. The obtained result is displayed on, for example, the display device 13, and based on the display result and the like,
In step S9, cross stroke noise is checked.

[0026]

As is apparent from the above description,
In the present invention, each line of the LSI printed wiring board,
The signal propagation direction of the interlayer line or via, or the line of interest, the other line within the noise influence range of the line and via, the other interlayer line, or the via in the signal propagation direction of the other direction Since lines can be displayed, designers can easily understand which wiring patterns, including the signal propagation direction, are dangerous based on the display results, and can consider the effects of noise and LSI / printed wiring. Board design can be done.

Furthermore, since the parallel wiring length of each line can be determined in consideration of the signal propagation direction of the LSI printed wiring board, wiring that is not affected by noise is not determined to be dangerous, and accurate noise check can be performed. Can be performed, and which wiring pattern is dangerous can be easily grasped.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a flowchart of an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a net of an LSI / printed wiring board.

[Explanation of symbols]

1,11 library 2,12 net information library 3 CAD system 3a net information investigation means 3b parallel line length check means 4,13 display device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-333979 (JP, A) JP-A-3-31780 (JP, A) JP-A-2-271474 (JP, A) JP-A-4- 127375 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 17/50 666 G06F 17/50 672 JICST file (JOIS)

Claims (7)

(57) [Claims] An LSI / printed circuit board CAD system for performing a noise check of an LSI / printed circuit board based on a wiring pattern of the LSI printed circuit board and net information such as a signal propagation direction in each line. A device, a wiring pattern of each line, a net information library storing signal propagation directions and signal strengths of each line, and a net to be checked when the net to be checked is input.
About the net to be checked from the
The wiring pattern and the net information on the signal propagation direction of the line.
Information is read and the signal propagation method of the net to be checked
And a net information investigating means for displaying a direction on the display device.
system. 2. The CAD system for an LSI / printed wiring board according to claim 1, wherein the signal propagation direction of the interlayer line is displayed by the net information inspection means. 3. The CAD system for an LSI / printed wiring board according to claim 1, wherein said net information investigation means displays a signal propagation direction in the via. 4. An LSI / printed circuit board CAD system for performing noise check of an LSI / printed circuit board based on a wiring pattern of the LSI printed circuit board and net information such as a signal propagation direction in each line. A device, a net information library storing a wiring pattern of each line, a signal propagation direction and a signal strength of each line, a library storing an influence range of noise according to the line signal strength, and a wiring pattern from the net information library. And read out the signal propagation direction and signal strength information of the line, and
The influence range of the noise corresponding to the signal strength is read out from the library, and the signal strength of the line of interest is obtained.
When, in response to the read signal strength Ri by the library Roh
From the influence range of the noise,
Seeking circumference, seeking a signal propagation direction of the line within the influence range, attention
Line and other lines that are within the noise range of the line
CAD system LSI · printed wiring board, characterized in that the signal propagation direction of the line and a net information checking means for displaying on the display device. 5. An inter-line line whose signal propagation direction is opposite to a line of interest and other inter-layer lines within a noise influence range of the line is displayed by the net information investigation means. 4. A CAD system for LSI and printed wiring boards. 6. The LSI according to claim 4, wherein said net information investigating means displays vias in which the signal propagation direction is opposite to the via of interest and other vias within the noise influence range of the via.・ CAD system for printed wiring boards. 7. Based on the net information signal propagating direction or the like in the LSI printed circuit board wiring pattern and each line, a CAD system LSI-printed wiring board which performs noise check LSI-printed circuit board, a display Device , net information library storing wiring pattern of each line, signal propagation direction and signal strength of each line, maximum parallel line length not affected by noise, and range affected by noise according to line signal strength The wiring pattern, the signal propagation direction and the net information of the signal strength of the line are read from the net information library, and the signal strength of the line of interest is obtained.
And a node corresponding to the signal strength read from the library.
From the influence range of the noise,
Seeking circumference line of the signal within the noise influence range of the focused line
Of the line of interest depending on the propagation direction of the
Net information researcher that calculates and records the parallel line length with the line
With reference to the column and the maximum parallel line length stored in the above library,
CAD system LSI · printed wiring board is characterized in that a parallel line length check means for checking the parallel line length of each line obtained by the net information checking means.