JP3961786B2 - Noise analysis method and apparatus, storage medium, and computer program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a noise analysis method and apparatus, a storage medium, and a computer program. In particular, an electronic circuit such as a large scale integrated circuit (LSI), a multichip module (MCM), a printed circuit board (PCB), and the like is obtained by computer aided design (CAD). Noise analysis method and apparatus for analyzing noise that may occur in an electronic circuit when designing, a computer-readable storage medium storing a computer program for causing a computer to perform such noise analysis, and such a computer program About.
[0002]
In recent years, with the miniaturization and speeding up of various electronic circuits, noise analysis when designing electronic circuits has become important. Noise generated in an electronic circuit is required to be analyzed accurately and at high speed.
[0003]
[Prior art]
Conventionally, various noise analysis tools for performing noise analysis when designing an electronic circuit have been proposed. The noise analysis tool performs noise analysis and noise check using a circuit simulator after the electronic circuit mounting design, and determines noise countermeasures for suppressing noise. The design of the electronic circuit is changed as necessary based on the determined noise countermeasures. After such a design change, noise analysis and noise check are performed again, and the above procedure is repeated until the noise falls within the allowable range.
[0004]
The main noises to consider when designing electronic circuits are reflection noise and crosstalk noise. Usually, the reflected noise is generated due to mismatch between the internal resistance of the driver and the characteristic impedance of the transmission line. On the other hand, the crosstalk noise largely depends on the signal transmission direction, the driving capability of the driver, the gap between adjacent patterns, and the like. Usually, since the analysis of the crosstalk noise requires information of adjacent patterns, the noise analysis and the noise check are performed using the mounting design data after the mounting design of the electronic circuit. Here, the information of adjacent patterns includes a pattern gap, a distance in which the patterns run in parallel, a position where the patterns are parallel on the transmission line, and the like.
However, in the conventional noise analysis method, as described below, the signal transmission direction is not specified when performing bus noise analysis.
[0005]
FIG. 1 is a diagram for explaining noise analysis when there are three bidirectional nets. A net refers to a portion composed of at least one circuit element of interest when designing an electronic circuit. Here, for example, when a transmission signal waveform between the driver / receiver C and the receiver / driver D (hereinafter referred to as “C-D”) is viewed, adjacent nets, that is, between the driver / receiver A and the receiver / driver B (hereinafter referred to as “C-D”). , A-B) and crosstalk noise due to a transmission signal waveform between the driver / receiver E and the receiver / driver F (hereinafter referred to as EF) must be considered.
[0006]
In this case, with respect to the transmission direction of C-> D in (1), crosstalk noise is analyzed between A and B in consideration of the transmission direction of A-> B and the transmission direction of B-> A. Necessary. Also, with respect to the transmission direction of D-> C in (2), the analysis of crosstalk noise is also performed between A and B in consideration of the transmission direction of A-> B and the transmission direction of B-> A. Necessary. Similarly, between E-F, it is necessary to analyze crosstalk noise in consideration of the transmission direction of E-> F and the transmission direction of F-> E.
[0007]
For this reason, when there are many adjacent wirings, a great amount of time is required for noise analysis. In addition, the transmission direction of B-> A and F-> E is opposite to the transmission direction of C-> D with respect to the transmission direction of C-> D. large.
[0008]
[Problems to be solved by the invention]
For example, if the transmission direction is always the same between C-D and EF, there is no F-> E transmission direction with respect to the C-> D transmission direction. In this case, it is useless to perform noise analysis in the transmission direction of F-> E with respect to the transmission direction of C-> D. Such useless noise analysis not only increases the noise analysis time, but also obtains a noise analysis result as if noise larger than the actually generated crosstalk noise is generated.
[0009]
In other words, the conventional noise analysis method does not specify the signal transmission direction when performing bus noise analysis, so noise analysis is performed for combinations of signals that are not actually transmitted for crosstalk noise in bidirectional signals. There was a problem of being done. For this reason, useless noise analysis is performed, noise analysis time increases, and there is a problem that an erroneous noise analysis result is obtained as if noise larger than the actual crosstalk noise is generated. there were.
[0010]
Accordingly, the present invention provides a noise analysis method and apparatus, and a storage medium that can prevent useless noise analysis for a combination of signals that are not actually transmitted to shorten noise analysis time and obtain an accurate noise analysis result. An object of the present invention is to provide a computer program.
[0011]
[Means for Solving the Problems]
The above problem is based on circuit data in which a signal transmission direction is the same as that of a bus in which the signal transmission direction is opposite, and a bus whose signal transmission direction is the same direction is crossed only in the same direction. This can be achieved by a noise analysis method including a step of analyzing talk noise.
[0012]
The above problem is based on circuit data in which the signal transmission direction is the same direction and the bus in which the signal transmission direction is the reverse, and the bus having the same signal transmission direction is only in the same direction. This can also be achieved by a noise analyzing apparatus characterized by including an analyzing means for analyzing crosstalk noise.
[0013]
The above-described problem is a computer-readable storage medium storing a program for causing a computer to have a noise analysis function. The program includes a bus in which the signal transmission direction is the same direction, and a bus in the reverse direction. For a bus whose signal transmission direction is the same based on the circuit data distinguished from each other, a storage medium characterized by including an analysis procedure for causing the computer to analyze the crosstalk noise only in the same direction is also included. Can be achieved.
[0014]
The above-described problem is a computer program for providing a computer with a noise analysis function, in which signal transmission is performed based on circuit data in which a bus having the same signal transmission direction and a bus having the opposite direction are distinguished. A bus having the same direction can also be achieved by a computer program including an analysis procedure for causing a computer to analyze crosstalk noise only in the same direction.
[0015]
Therefore, according to the present invention, a noise analysis method and apparatus that can prevent useless noise analysis for a combination of signals that are not actually transmitted to reduce noise analysis time and obtain an accurate noise analysis result, A storage medium and a computer program can be realized.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a noise analysis method and apparatus, a storage medium, and a computer program according to the present invention will be described below with reference to the drawings.
[0017]
【Example】
An embodiment of a noise analyzing apparatus according to the present invention will be described. This embodiment of the noise analysis apparatus uses an embodiment of a noise analysis method according to the present invention, an embodiment of a computer-readable storage medium according to the present invention, and an embodiment of a computer program according to the present invention. In this embodiment, the present invention is applied to a computer system. FIG. 2 is a perspective view showing a computer system to which the present invention is applied in this embodiment.
[0018]
A computer system 100 shown in FIG. 2 includes a main body 101 that generally includes a CPU, a disk drive, and the like, a display 102 that displays an image on a display screen 102 a according to instructions from the main body 101, and various information input to the computer system 100. And a modem 105 that accesses an external database or the like and downloads a computer program or the like stored in another computer system.
[0019]
A noise analysis program (or noise analysis software) for causing the computer system 100 to have a noise analysis function is stored in a portable recording medium such as the disk 110, or other computer system using a communication device such as the modem 105. Downloaded from the recording medium 106. The storage medium according to the present invention includes a recording medium such as the disk 110 storing the computer program according to the present invention. The recording medium constituting the storage medium according to the present invention is not limited to a portable recording medium such as a disk 110, an IC card memory, a floppy disk, a magneto-optical disk, or a CD-ROM. Various recording media accessible by a computer system connected via a communication device or communication means are included.
[0020]
FIG. 3 is a block diagram for explaining a configuration of a main part in the main body 101 of the computer system 100. In FIG. 1, a main body 101 includes a CPU 201 generally connected by a bus 200, a memory unit 202 including a RAM and a ROM, a disk drive 203 for the disk 110, and a hard disk drive 204. In the present embodiment, the display 102, the keyboard 103, and the mouse 104 are also connected to the CPU 201 via the bus 200 as shown in the figure, but they may be directly connected to the CPU 201. The display 102 may be connected to the CPU 201 via a known graphic interface (not shown) that processes input / output image data.
[0021]
The configuration of the computer system 100 is not limited to the configuration shown in FIGS. 2 and 3, and various known configurations may be used instead.
[0022]
First, noise analysis when there are three bidirectional nets will be described with reference to FIG. FIG. 1 is a diagram for explaining noise analysis when there are three bidirectional nets as described above. The noise analysis described in the following description is performed before circuit design, during circuit design, circuit element arrangement, circuit wiring arrangement, and the like.
[0023]
In FIG. 1, first, a bus between CD and a bus between EF are selected and designated as one bus group. The selection of the bus and the designation of the bus group are performed using the keyboard 103 and the mouse 104, for example, by displaying the net shown in FIG. To select a bus and specify a bus group, the buses displayed on the display 102 are selected and grouped, or a list of bus names assigned to the buses is displayed on the display 102 and a bus in the list is selected and grouped. You can do that. The specified bus group is passed to the noise analysis program. The noise analysis program analyzes the noise only in the transmission direction of E-> F for the transmission direction of C-> D based on the designated bus group. For the transmission direction of D-> C, noise in only the transmission direction of F-> E is analyzed. As for the bus between A and B, the noise analysis program analyzes the noise in both cases because it may be in the same transmission direction as the bus between C and D or in the opposite transmission direction.
[0024]
Next, noise analysis when a plurality of pins serving as drivers and receivers are connected to one net will be described with reference to FIG. FIG. 4 is a diagram for explaining a driver / receiver group.
[0025]
In FIG. 4, if the transmission directions of the six nets are the same, these six nets are designated as one bus group. In the case of the figure, for example, the bus group BG1 is designated. Also, in the net, a part whose pin is another part is designated on a part basis. At this time, if there are pins of different parts having the same transmission direction, these pins are designated as one driver / receiver group. In the case of the figure, for example, the driver / receiver group DRG1 is designated.
[0026]
For example, when the component PD is selected after the component PB is selected, a message indicating that the selection cannot be made is displayed on the display 102 because the pins of the same net cannot simultaneously become the pins of the driver. In the case of FIG. 4, only the combination of the component PB and the component PC or the component PD and the component PC can be designated as the driver / receiver group.
[0027]
Next, a driver / receiver group is designated with another name for another driver pin. In the case of FIG. 4, for example, the driver / receiver group DRG2 is designated. However, since only one component PD belongs to the driver / receiver group DRG2, the designation of the driver / receiver group DRG2 can be omitted.
[0028]
The noise analysis program first analyzes a pin of a part PA for which no driver / receiver group is specified as a driver. Of the components PA, the signals from the pins specified for the bus group are all analyzed in the same transmission direction. At this time, the pins of the bus group BG1 among the pins of the products PB, PC, and PD are all receivers.
[0029]
Next, when the component PB is a driver, the component PC of the same driver / receiver group DRG1 is also a driver. At this time, of the pins of the parts PA and PD, all the pins belonging to the bus group BG1 are receivers.
[0030]
The component PE is, for example, a damping resistor, and the net is cut here. However, by registering information indicating which pins of the damping resistor and which pins are connected to, for example, a library in the memory unit 202, the connection of the net can be traced. In this case, the driver pins and the receiver pins are connected.
[0031]
Next, noise analysis for a bus group and a driver / receiver group across a plurality of LSIs, PCBs, MCMs, etc. will be described with reference to FIG. FIG. 5 is a diagram for explaining a bus group and a driver / receiver group straddling a plurality of LSIs, PCBs, MCMs, and the like. In the figure, the same parts as those in FIG.
[0032]
In FIG. 5, the bus group BG1 and the driver / receiver groups DRG1 and DRG2 straddle a plurality of printed circuit boards PCB1 to PCB3. In this case, a bus group and a driver / receiver group are designated for each piece of data on a printed circuit board (PCB). When using a tool for displaying data of a plurality of printed circuit boards (PCBs) at once, a bus group and a driver / receiver group can be specified for a plurality of printed circuit boards (PCBs) at a time. At this time, the bus groups having the same name are handled as one bus group. Also, a driver / receiver group having the same name in one bus group is treated as the same driver / receiver group.
[0033]
For example, when the same PCB is mounted on the motherboard or when the same LSI is mounted on the PCB, the same setting can be adopted for the same LSI by using the same bus group definition file. Also, even if the same PCB or LSI is used, if different bus groups or different driver / receiver groups are used, different bus group definition files are created for each PCB or LSI.
[0034]
FIG. 6 is a flowchart for explaining the noise analysis processing of the CPU 201 in this embodiment.
[0035]
In FIG. 6, step S1 performs a circuit input process for inputting information relating to the circuit to be designed. The circuit input process can be performed by operating the keyboard 103, accessing another computer system and reading it via the modem 105, or reading it from a recording medium such as the disk 110 storing the information. The information regarding the circuit to be designed includes circuit information including information regarding elements, wiring, element constants, arrangement of elements and wiring, and the like constituting the circuit, and bus information regarding the bus. In step S2, circuit data including circuit information and bus information is stored in a storage unit such as the memory unit 202, for example.
[0036]
In step S3, a placement and routing process for placing circuit elements and placing circuit wiring is performed based on the circuit information and bus information stored in the memory unit 202. In step S3, step S3A performs bus group designation processing using bus information. The bus group designation process designates and edits a bus group including addition of a driver / receiver group. If no bus information is input by the circuit input process, the bus group is specified and edited by the bus group specifying process.
In step S4, the wiring data obtained as a result of the wiring arrangement process is stored in a storage unit such as the memory unit 202, and the bus group data obtained as a result of the bus group designation process is stored in a storage unit such as the memory unit 202. Store. In step S5, noise analysis processing is performed using the wiring data and bus group data stored in the memory unit 202. Depending on the type of noise analyzed by the noise analysis process, circuit data stored in the memory unit 202 is also used.
[0037]
FIG. 7 is a flowchart for explaining the bus group definition processing. This bus group definition processing is included in the bus group designation processing in step S3A shown in FIG. In FIG. 7, step S <b> 11 selects a net from the circuit displayed on the display 102 or a list of nets constituting the circuit (net list) using the keyboard 103 and the mouse 104. In step S12, it is determined whether the selection of the net has been completed. If the determination result is NO, the process returns to step S11. On the other hand, if the decision result in the step S12 is YES, a step S13 creates a bus group definition file by selecting and defining a bus group based on the selected net, and the process ends. The bus group definition file is stored in the memory unit 202, for example.
[0038]
FIG. 8 is a diagram for explaining the bus group definition file. When the circuit is composed of LSI1 to LSI4, bus group BUS-1, and driver / receiver group DRRV-1 as shown in the figure, the bus group definition file is as follows.
[0039]
HEAD;
PCBNAME PCB-1;
BUS_GROUP BUS-1;
NETNAME A1 A2 A3 A4;
DR_RV_GROUP DRRV-1;
LOCATION LSI2 LSI3;
END;
END;
FIG. 9 is a flowchart for explaining driver / receiver group definition processing. This driver / receiver group definition process is included in the bus group designation process in step S3A shown in FIG. 9, step S21 selects a bus group by designating a bus using the keyboard 103 or the mouse 104 from the circuit displayed on the display 102 or a list of buses constituting the circuit. In step S22, a part is selected using the keyboard 103 or the mouse 104 from the circuit displayed on the display 102 or a list of parts constituting the circuit. In step S23, the definition of the driver / receiver group is checked. In step S24, it is determined whether or not there is an error in the definition of the driver / receiver group. If there is an error in which the transmission direction is different from that of other drivers / receivers and the determination result is NO, the process proceeds to step S22. Return to. On the other hand, if the decision result in the step S24 is YES, a step S25 creates a driver / receiver group definition file that defines a driver / receiver group, and the process ends. The driver / receiver group definition file is stored in the memory unit 202, for example. The driver / receiver group definition file may be provided in the bus group definition file.
[0040]
FIG. 10 is a flowchart for explaining the noise analysis processing. This noise analysis process is performed in step S5 shown in FIG. In FIG. 10, step S31 determines an analysis target net. The analysis target net is determined by selecting a net using a keyboard 103 or a mouse 104 from a circuit displayed on the display 102 or a list of nets constituting the circuit (net list). In step S32, a net that gives crosstalk noise to the determined analysis target net is selected using the keyboard 103 and the mouse 104 in the same manner as in step S31. In step S33, it is determined whether or not all analysis of the analysis target net is completed. If the determination result is YES, the process ends.
[0041]
On the other hand, if the decision result in the step S33 is NO, a step S34 decides whether or not there is a bus definition in the circuit data. That is, step S34 determines whether there is a bus group definition file. If the decision result in the step S34 is NO, a step S35 performs a noise analysis for the transmission direction in the same direction and the reverse direction on the bus of the analysis target net by a well-known method, and the process returns to the step S32. If the decision result in the step S34 is YES, a step S36 performs a noise analysis only with respect to the same transmission direction based on the bus group definition file and the driver / receiver group definition file, and the process is performed in a step S32. Return to. As a result, step S36 does not perform noise analysis for combinations of transmission directions that do not actually exist, so that the analysis time is shortened and noise larger than the actually generated crosstalk noise is erroneously estimated. Such inconveniences can be prevented.
[0042]
FIG. 11 is a diagram illustrating a crosstalk noise waveform when the bus group definition is not performed. In FIG. 11, the vertical axis represents voltage (V) and the horizontal axis represents time (ns). The crosstalk noise waveform shown in FIG. 11 is obtained as a result of performing noise analysis on the transmission direction in the same direction and the reverse direction in step S35 of FIG. 10 on the noise analysis target net shown in FIG. As can be seen from FIG. 11, the maximum crosstalk noise from the adjacent net is 59 mV.
[0043]
FIG. 12 is a diagram illustrating a crosstalk noise waveform when the bus group definition is performed. In FIG. 12, the vertical axis represents voltage (V) and the horizontal axis represents time (ns). The crosstalk noise waveform shown in FIG. 12 is obtained as a result of performing noise analysis on the noise analysis target net shown in FIG. 1 only in the same transmission direction in step S36 of FIG. As can be seen from FIG. 12, the maximum crosstalk noise from the adjacent net is 17 mV.
[0044]
In the case of a bus in which the signal transmission direction is the same direction, there is no need to consider the reverse signal flow. The crosstalk noise caused by the reverse signal flow is larger than the crosstalk noise caused by the same signal flow. Therefore, if the reverse signal flow is taken into consideration, the crosstalk noise is much larger than the actual crosstalk noise. Talk noise is estimated. However, as is clear from the comparison between FIG. 12 and FIG. 11, when there is no need to consider the flow of signals in the reverse direction as in this embodiment, noise analysis is performed only in the same transmission direction. Accurate crosstalk noise can be estimated.
[0045]
When linking with the concept design system or the circuit entry system, the same processing as in the above embodiment may be performed based on the virtually wired data.
[0046]
The present invention includes the inventions appended below.
[0047]
(Supplementary note 1) Based on circuit data in which a signal transmission direction is the same direction and a bus in which the signal transmission direction is the opposite direction, a bus having the same signal transmission direction is crossed only in the same direction. A noise analysis method comprising a step of analyzing talk noise.
[0048]
(Supplementary Note 2) Buses having the same signal transmission direction are grouped and managed as a bus group definition file, and parts having the same signal transmission direction are grouped in the bus group definition file. The noise analysis method according to (Appendix 1), which is included as a driver / receiver group.
(Supplementary Note 3) The noise analysis method according to (Supplementary Note 2), including a step of considering the connected nets as the same bus group and the same driver / receiver group when performing noise analysis across a plurality of circuit portions.
[0049]
(Appendix 4) The noise analysis method according to any one of (Appendix 1) to (Appendix 3), including a step of designating a bus having the same signal transmission direction.
[0050]
(Supplementary Note 5) Based on circuit data in which a signal transmission direction is the same direction and a bus in which the signal transmission direction is the reverse, a bus having the same signal transmission direction is crossed only in the same direction. A noise analysis apparatus comprising analysis means for analyzing talk noise.
[0051]
(Supplementary Note 6) The buses having the same signal transmission direction are grouped and managed as a bus group definition file, and the bus group definition file includes components having the same signal transmission direction. Are grouped and included as a driver / receiver group. The noise analysis apparatus according to (Appendix 5),
[0052]
(Supplementary note 7) A computer-readable storage medium storing a program for giving a computer a noise analysis function,
The program crosses only the same direction for buses with the same signal transmission direction based on circuit data in which the buses with the same signal transmission direction and the buses with the opposite direction are distinguished. A storage medium comprising an analysis procedure for causing a computer to perform talk noise analysis.
[0053]
(Supplementary Note 8) The program includes a procedure in which buses having the same signal transmission direction are grouped and managed by a computer as a bus group definition file. The bus group definition file includes a signal transmission direction. The storage medium according to (Appendix 7), wherein components having the same direction are grouped and included as a driver / receiver group.
[0054]
(Supplementary note 9) A computer program for giving a computer a noise analysis function,
Based on the circuit data in which the signal transmission direction is the same as the bus in the opposite direction, the bus with the same signal transmission direction is analyzed for crosstalk noise only in the same direction. The computer program characterized by including the analysis procedure which makes a computer perform.
[0055]
(Supplementary Note 10) Buses having the same signal transmission direction include a procedure of grouping them and managing them as a bus group definition file. The bus group definition file includes a signal transmission direction in the same direction. The computer program according to (Appendix 9), wherein certain parts are grouped and included as a driver / receiver group.
[0056]
Although the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope of the present invention.
[0057]
【The invention's effect】
According to the present invention, a noise analysis method and apparatus and a storage medium capable of preventing noise analysis for a combination of signals that are not actually transmitted to reduce noise analysis time and obtaining an accurate noise analysis result. In addition, a computer program can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining noise analysis when there are three bidirectional nets.
FIG. 2 is a perspective view showing a computer system to which the present invention is applied in the embodiment.
FIG. 3 is a block diagram for explaining a configuration of a main part in a main body of the computer system.
FIG. 4 is a diagram for explaining a driver / receiver group;
FIG. 5 is a diagram for explaining bus groups and driver / receiver groups straddling a plurality of LSIs, PCBs, MCMs, and the like.
FIG. 6 is a flowchart for explaining noise analysis processing;
FIG. 7 is a flowchart for explaining bus group definition processing;
FIG. 8 is a diagram for explaining a bus group definition file.
FIG. 9 is a flowchart for explaining driver / receiver group definition processing;
FIG. 10 is a flowchart for explaining noise analysis processing;
FIG. 11 is a diagram illustrating a crosstalk noise waveform when the bus group definition is not performed.
FIG. 12 is a diagram showing a crosstalk noise waveform when a bus group is defined.
[Explanation of symbols]
100 computer system
102 display
103 keyboard
104 mouse
105 modem
110 disks
201 CPU
202 Memory unit
BG1 bus group
DRG1, DRG2 driver / receiver group

Claims (6)

A computer-based noise analysis method for analyzing crosstalk noise based on circuit data including a bus in which the signal transmission direction is the same direction and a bus in the opposite direction,
A bus group definition file is created by grouping buses having the same signal transmission direction based on nets in the circuit data selected by the input means and defining a bus group, and defining the bus group definition Storing the file in a storage means;
Based on the stored in the circuit data and said storage means said bus group definition file, the transmission direction of the signal for the bus in the same direction, the including the step of analyzing the crosstalk noise only for the same direction A characteristic noise analysis method. 2. The noise analysis method according to claim 1, wherein parts having the same signal transmission direction are grouped and included in the bus group definition file as a driver / receiver group.   3. The noise analysis method according to claim 2, further comprising the step of considering the connected nets as the same bus group and the same driver / receiver group when performing noise analysis across a plurality of circuit portions. A noise analysis device for analyzing crosstalk noise based on circuit data including a bus in which the signal transmission direction is the same direction and a bus in the opposite direction ,
Input means;
Storage means;
A bus group definition file is created by grouping buses having the same signal transmission direction based on a net in the circuit data selected by the input means and defining a bus group, and generating the bus group definition file Means for storing a definition file in the storage means;
Based on the circuit data and the bus group definition file stored in the storage means, for a bus whose signal transmission direction is the same direction, an analysis means for analyzing crosstalk noise only in the same direction is provided. A noise analyzer. A computer-readable storage medium storing a program for causing a computer to analyze crosstalk noise based on circuit data including a bus in which the signal transmission direction is the same direction as that of the bus, The program
  Causing the computer to create a bus group definition file by grouping buses having the same signal transmission direction based on the net selected by the input means and defining the bus group; Storing the data in the storage means;
  Analysis that causes the computer to analyze crosstalk noise only in the same direction for a bus having the same signal transmission direction based on the circuit data and the bus group definition file stored in the storage means A storage medium comprising a procedure. A computer program for causing a computer to analyze crosstalk noise based on circuit data including a bus in which the signal transmission direction is the same direction and a bus in the opposite direction,
  Causing the computer to create a bus group definition file by grouping buses having the same signal transmission direction based on the net selected by the input means and defining the bus group; Storing the data in the storage means;
  Analysis that causes the computer to analyze crosstalk noise only in the same direction for a bus having the same signal transmission direction based on the circuit data and the bus group definition file stored in the storage means A computer program comprising a procedure.

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