JP2011008524A - Design support device and design support method - Google Patents

Abstract

A design support apparatus capable of supporting determination of an IC placement position on a printed circuit board in consideration of reduction of EMI radiation is realized.
A current calculation unit 133 calculates a value of a current flowing from each driver (each output pin) of each IC for each frequency band. The current direction determination unit 134 extracts all output pins and all input pins of all ICs mounted on the printed circuit board, and determines the current direction for each extracted output pin. The current vector calculation unit 135 calculates a value of a current flowing from each output pin and a current vector indicating the direction of the current for each frequency band. The combined vector calculation unit 136 calculates a combined vector indicating the sum of current vectors corresponding to the same frequency band for each frequency band. The EMI evaluation unit 137 outputs a predicted value of the electromagnetic radiation of the printed circuit board based on the calculated magnitude of the combined vector of each frequency band.
[Selection] Figure 1

Description

  The present invention relates to a design support apparatus and a design support method for supporting the design of industrial products such as printed circuit boards for computers.

  In recent years, various CAD (Computer Aided Design) systems that support the design of industrial products have been developed. In designing a printed circuit board for a computer, the arrangement positions of various components on the printed circuit board are usually determined in consideration of constraints such as the height limit of the components. By the way, in recent personal computers, CPUs and chipsets have been increased in speed, and high-speed signal interfaces for communication with peripheral devices have also been installed. For this reason, countermeasures against electromagnetic interference (EMI) have become extremely important when designing / manufacturing printed circuit boards for computers. One factor of EMI radiation is a loop antenna. The loop antenna is formed by a current flowing through the transmission line on the printed circuit board and a return current flowing through the reference layer.

  In Patent Document 1, each circuit on a substrate is grouped for each frequency based on circuit current and circuit frequency, and EMI countermeasures corresponding to the frequency band of the circuit block are applied to each circuit block obtained by this grouping. A system is disclosed.

JP 2002-259478 A

  However, in the system of Patent Document 1, no consideration is given to component arrangement for reducing the EMI radiation itself of the entire board. Depending on the arrangement position of each component such as an IC, there is a possibility that the EMI radiation of the entire substrate increases due to a bias in current distribution or the like. Therefore, it is necessary to realize a new technology capable of supporting component placement that can reduce the EMI radiation itself of the entire board.

  The present invention has been made in consideration of the above-described circumstances, and provides a design support apparatus and a design support method capable of supporting the determination of the placement positions of ICs on a printed circuit board in consideration of reduction of EMI radiation. The purpose is to provide.

  In order to solve the above-described problem, a design support apparatus according to the present invention includes a designation unit that designates a position on a printed circuit board in which each of a plurality of integrated circuits (ICs) is arranged according to an operation of an input device, A storage device that stores model information of each IC and connection information indicating a connection relationship between the pins of the plurality of ICs, and a value of a current flowing from each output pin of each of the plurality of ICs based on the model information Current direction calculating means for calculating current direction from each of the output pins based on the connection information and designated positions of each of the plurality of ICs; Current vector calculation means for calculating a current vector indicating the value of current flowing from each of the output pins and the direction of the current for each frequency band, and a current vector corresponding to the same frequency band A combined vector calculation means for calculating a combined vector indicating the sum of the vectors for each frequency band, and prediction of electromagnetic radiation of the printed circuit board based on the calculated combined vector size of each frequency band Output means for outputting a value.

  According to the present invention, it is possible to assist the determination of the placement position of the IC on the printed circuit board in consideration of the reduction of EMI radiation.

1 is a block diagram showing a system configuration example of a design support apparatus according to an embodiment of the present invention. The figure for demonstrating the loop antenna of the transmission line considered in the design support apparatus of the embodiment. The figure which shows the example of the electric current amount calculation process performed by the design support apparatus of the embodiment. The figure which shows the example of the current direction specific process performed by the design support apparatus of the embodiment. The figure which shows the example of the current vector calculation process performed by the design support apparatus of the embodiment. The figure which shows the example of the synthetic | combination vector calculated by the design support apparatus of the embodiment. 6 is an exemplary flowchart illustrating an example of a procedure of design support processing executed by the design support apparatus of the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration example of a design support apparatus according to an embodiment of the present invention. This design support apparatus is a CAD apparatus for supporting design support of industrial products and verification of the design. For example, for design support of products including a printed circuit board (PCB) used as a system board of a computer. Used. This design support apparatus has a function for supporting component placement for reducing EMI radiation itself of the entire printed circuit board.

  The design support apparatus is realized by a computer. This design support apparatus includes an input device 11, a system main body 12, and a display device 13. The input device 11 is a computer keyboard or a mouse. The display device 13 is a computer display. The system main body 12 is realized by, for example, a computer CPU, memory, I / O controller, and the like. The system main body 12 includes a main processing unit 121 and a storage device 122. The main processing unit 121 is an arithmetic processing unit for executing a design support function, and is realized by, for example, a design support program executed by a CPU of a computer. The storage device 122 is realized by a storage device such as a hard disk drive. The storage device 122 stores design information of the printed circuit board to be designed. This design information includes, for example, board shape information, LSI model information, LSI placement information, pin information, connection information, and the like.

  The board shape information is data indicating the shape and dimensions of the printed circuit board to be designed. In the present embodiment, for example, a multilayer wiring board is used as a printed circuit board to be designed. The LSI model information and the pin information are model information that defines each component of an integrated circuit (IC) such as an LSI that is a component to be placed on the printed circuit board. The LSI model information includes data defining an electrical model of each integrated circuit (IC). The electrical model is model data for indicating the operation (output voltage waveform data of each driver, etc.) of each IC on the printed circuit board in units of pins of each IC. With this electrical model, it is possible to simulate the operation of each driver circuit in each IC. As the electrical model, an IBIS (I / O Buffer Information Specification) model or a SPICE (Simulation Program with Integrated Circuit Emphasis) model can be used. In addition, an actual measurement value such as an output voltage waveform corresponding to each pin can be used as an electrical model. The LSI model information may also include component library information indicating the component shape (shape, dimension, position of each pin) of each IC. The pin information is pin definition data indicating, for each pin included in each IC, whether the pin is an output pin for outputting a signal or an input pin for inputting a signal. Pin information can also define I / O pins that are shared for both signal output and signal input.

  The LSI placement information is coordinate data indicating the placement position on the printed circuit board where each IC is to be placed. An operator (designer) can designate the position of each IC on the printed circuit board by operating the input device 11. Coordinate information indicating the placement position of each IC designated by the operation of the input device 11 by the operator (designer) is stored in the storage device 122 as LSI placement information. The connection information is data indicating a logical connection relationship (input / output relationship) between pins of a plurality of ICs. For example, the connection information indicates, for each pin number of the output pin of each IC, the pin number of the input pin of another IC to which the pin number is connected.

  The design support apparatus calculates (simplely) the amount of EMI radiation of the entire printed circuit board corresponding to the current component arrangement at the stage of determining the arrangement position of each IC on the printed circuit board, and the calculation result The component placement support function is used to evaluate or optimize the placement position of each IC. In this component arrangement support function, for example, a loop antenna is considered as a factor of EMI radiation.

  FIG. 2 shows an example of this loop antenna. As shown in FIG. 2, the driver circuit 101 in the IC arranged on the printed circuit board is connected to another IC on the printed circuit board via the transmission line 100 on the wiring layer of the printed circuit board. The receiver circuit 102 is connected. In this case, when the driver circuit 101 transmits a signal to the receiver circuit 102, a current corresponding to the signal waveform flows from the driver circuit 101 to the receiver circuit 102 via the transmission line 100. Further, a return current flows from the receiver circuit 102 to the driver circuit 101 via a reference plane (ground plane or the like) 200 that is an inner layer in the printed circuit board. Thus, a loop antenna is formed by the current flowing on the wiring layer of the printed circuit board and the return current flowing on the reference layer of the printed circuit board, and a magnetic field (rot H) is generated by the loop antenna. The direction of the magnetic field (rot H) of the loop antenna is the direction obtained by rotating the direction of the current flowing on the wiring layer by 90 degrees counterclockwise. The component placement support function of the present embodiment has a current (current value) corresponding to each loop antenna and a direction of the current so that the influence of EMI by each loop antenna formed on the printed circuit board is offset as much as possible. Based on the above, the parts placement is supported.

  More specifically, the component placement support function of the present embodiment predicts the EMI radiation amount of the entire printed circuit board corresponding to the current component placement. In the present embodiment, the output currents of all the output pins corresponding to the ICs arranged on the printed circuit board and the directions of the output currents are shown based on the design information of the system board and the current component arrangement. A current vector is determined. Then, the magnitude of the combined vector that is the sum of the current vectors corresponding to all the output pins is calculated. In the present embodiment, a predicted value of the EMI radiation amount of the entire printed circuit board is obtained based on the magnitude of this combined vector. Note that it is not always necessary to calculate the current vectors of all the output pins of all the ICs. For example, only for some ICs (for example, CPU, chipset, memory, etc.) having a relatively large output current. The current vector of the output pin of the IC may be calculated.

  The magnitude of the combined vector represents the degree of bias in the direction in which current flows. The stronger the bias in the direction of current flow, the greater the amount of EMI radiation across the printed circuit board. Therefore, by determining the position of each IC on the printed circuit board so that the size of the combined vector becomes as small as possible, the influence of EMI by each loop antenna can be offset, and the EMI radiation of the entire board can be canceled. It can be reduced.

  In the loop antenna, the direction of current flowing on the wiring layer and the direction of current flowing on the reference plane (or reference layer) are opposite to each other. For this reason, when calculating the current vector, only the current flowing from each output pin, that is, the current flowing on the wiring layer need only be considered.

  In order to realize the above-described component placement support function, the main processing unit 121 includes an input processing unit 131, a component placement processing unit 132, a current calculation unit 133, a current direction determining unit 134, as shown in FIG. A current vector calculation unit 135, a combined vector calculation unit 136, an EMI evaluation unit 137, a display processing unit 138, and a component arrangement change unit 139 are provided. The input processing unit 131 is used to process data and commands (CAD operation commands) input from the input device 11.

  The component placement processing unit 132 designates the placement position on the printed circuit board where each of the plurality of integrated circuits (ICs) should be placed in accordance with the operation of the input device 11 by the user. For example, the user operates a pointing device such as a mouse to move an object corresponding to each IC to an arbitrary position on the image of the printed circuit board displayed on the design screen of the display device 13. The arrangement position of each IC can be designated. The component placement processing unit 132 generates coordinate data indicating the position on the printed circuit board corresponding to the designated placement position of each IC, and stores the generated coordinate data in the storage device 122 as LSI placement information.

  The current calculation unit 133 reads the LSI model information from the storage device 122, and calculates the value of the current flowing from each output pin of a plurality of ICs arranged on the printed circuit board for each frequency band based on the read LSI model information. To do. An example of a method for calculating the value of the current flowing from each output pin is shown in FIG. In FIG. 3, transient analysis is executed based on the rising waveform or falling waveform of the output voltage signal of each output pin. The rising waveform or falling waveform of the output voltage signal is given by the output voltage waveform data of each output pin included in the LSI model information. By the transient analysis, the waveform of the output voltage signal (transient response waveform) can be converted into the waveform of the output current (transient response waveform). By performing frequency analysis on the waveform of the output current using, for example, Fourier transform (FFT), the waveform of the output current indicating the distribution of the current value with respect to time has a frequency characteristic indicating the distribution of the magnitude of the current value with respect to the frequency. Since it is converted into information, the value of the current flowing from each output pin can be calculated for each frequency band. Current from any output pin flows through the same printed circuit board wiring layer. For this reason, in the transient analysis, the same inductance value and the same capacitance value may be used when calculating the output current of any output pin.

  In the present embodiment, for example, a frequency range of 0 to 1 GHz is used as a frequency range to be subjected to EMI countermeasures. In this case, the frequency range of 0 to 1 GHz is divided into a plurality of continuous frequency bands each having a predetermined bandwidth. If the bandwidth is 20 MHz, the frequency range of 0 to 1 GHz is divided into 50 continuous frequency bands (FB1 to FB50). The current calculation unit 133 can obtain the value of the output current of each output pin for each of the 50 frequency bands (FB1 to FB50). In other words, the current distribution for 50 frequency bands (FB1 to FB50) is obtained for each output pin.

  The current direction determination unit 134 reads the connection information from the storage device 122, and from each of the plurality of output pins based on the read connection information and the arrangement positions of the plurality of ICs specified by the component arrangement processing unit 132. The direction of the flowing current (current direction) is determined. In this case, the current direction determination unit 134 determines, for each output pin, the direction of a straight line connecting the output pin and the input pin to which the output pin is connected as the direction of the current flowing from the output pin.

  Note that it is not always necessary to determine the direction of the output current corresponding to each output pin of all the ICs to be mounted on the printed circuit board. For example, some specific ICs whose output current is larger than a reference value may be extracted from all the ICs, and the direction of the output current corresponding to each of the output pins of the extracted ICs may be determined.

  An example of the process for determining the current direction is shown in FIG. In FIG. 4, it is assumed that three ICs 301, 302, and 303 are arranged as illustrated on a printed circuit board 300 having a multilayer structure including a wiring layer and a reference plane. In FIG. 4, the symbol “O” indicates the output pin of the IC, and the symbol “I” indicates the input pin of the IC. As shown in FIG. 4, the current direction determining unit 134 moves between the output pin and the input pin between the driver pin (output pin) of one IC and the receiver pin (input pin) of another IC. The straight lines are connected to each other, and the direction of the straight line is determined as the direction in which the output current of the output pin flows. Which IC output pin is connected to which IC input pin is given by the above-described connection information. If the connection information simply indicates the connection between the pins and does not include information on the input / output relationship, the current direction determination unit 134 reads both the pin information and the connection information from the storage device 122, Determine the current direction.

  In practice, the output current flows along the pattern of the transmission line. However, since the component placement support function of this embodiment is executed at the stage of component placement, it is sufficient if only the approximate direction of the current flowing from each output pin can be grasped. Therefore, in this embodiment, the direction of the straight line from the output pin to the input pin is used as the direction of the current flowing from the output pin.

  Assume that the connection information (or connection information and pin information) indicates that the output pin 401 of the IC 301 and the input pin 404 of the IC 302 are connected. In this case, for example, the current direction determination unit 134 connects the output pin 401 of the IC 301 and the input pin 404 of the IC 302 with a straight line from the output pin 401 to the input pin 404, and determines the direction of the straight line of the output pin 401. The direction in which the output current flows is determined. The direction (D1) of the output current of the output pin 401 can be expressed by the following equation using, for example, a two-dimensional coordinate system (x, y) on the design screen.

D1 = (x2-x1, y2-y1)
Here, (x1, y1) is a coordinate indicating the position of the output pin 401 on the printed circuit board. (X2, y2) are coordinates indicating the position of the input pin 402 on the printed circuit board. The coordinates (x1, y1) of the output pin 401 can be obtained from, for example, the LSI arrangement information of the IC 301 and the component library information in the LSI model information of the IC 301. Similarly, the coordinates (x2, y2) of the input pin 402 can be obtained from, for example, coordinates indicating the arrangement position of the IC 302 and component model information of the IC 302.

  If the connection information (or connection information and pin information) indicates that the output pin 406 of the IC 303 and the input pin 403 of the IC 301 are connected, the current direction determination unit 134 inputs the output pin 406 of the IC 303 and the input of the IC 301. A straight line from the output pin 406 to the input pin 403 is connected to the pin 403, and the direction of the straight line is determined as the direction of the current flowing from the output pin 406. For connection between bidirectional pins (I / O pins), these I / O pins may be connected in both directions.

  The current vector calculation unit 135 corresponds to each output pin using the output current calculated for each output pin by the current calculation unit 133 and the direction of the output current determined for each output pin by the current direction determination unit 134. The current vector to be calculated is calculated for each frequency band FB. That is, 50 current vectors equal to the number of frequency bands (FB1 to FB50) are obtained for each output pin. Each current vector indicates an output current value [mA] in a certain frequency band FB and an output current direction [x, y]. This current vector can also be expressed by the horizontal component (Ix) of the output current and the vertical component (Iy) of the output current.

  An example of the current vector is shown in FIG. In FIG. 5, the value of the output current flowing from the output pin 401 and the current vector indicating the current direction, and the value of the output current flowing from the output pin 406 and the current vector indicating the current direction are schematically shown by thick arrows. Is shown in Since currents in opposite directions flow between the I / O pins, the sum of the current vector corresponding to the current output from the I / O pin and the current vector corresponding to the current input to the I / O pin is It becomes zero. Therefore, each I / O pin can be excluded from the current vector calculation target.

  1 calculates a combined vector indicating the sum of current vectors corresponding to the same frequency band FB for each of the above-described frequency bands FB1 to FB50. That is, 50 composite vectors corresponding to the 50 frequency bands FB1 to FB50 described above are calculated. For example, the combined vector corresponding to the frequency band FB16 having a band from 300 MHz to 320 MHz is obtained by the sum of all current vectors corresponding to the respective current values belonging to the frequency band (300 MHz to 320 MHz). Further, the combined vector corresponding to the frequency band FB17 having a band from 320 MHz to 340 MHz is obtained by the sum of all current vectors corresponding to the current values belonging to the frequency band (320 MHz to 340 MHz).

  FIG. 6 shows a combined vector indicating the sum of a current vector corresponding to the output current of the output pin 401 and a current vector corresponding to the output current of the output pin 406 as an example of the combined vector. If the directions of two currents corresponding to the same frequency band are opposite to each other, the combined vector corresponding to each of the currents becomes smaller. This means that the EMI caused by each of these currents is offset. In this embodiment, since the sum of current vectors corresponding to the same frequency band is calculated for each frequency band, the amount of EMI radiation is calculated for each frequency band in consideration of the EMI cancellation effect due to component placement. be able to.

  The EMI evaluation unit 137 in FIG. 1 outputs an EMI predicted value (predicted value of electromagnetic radiation) of the entire printed circuit board based on the magnitude of the combined vector of each frequency band calculated by the combined vector calculating unit 136. The predicted EMI value is displayed on the display (on the design screen of the display device 13) by the display processing unit 138 as an evaluation value related to the electromagnetic interference corresponding to the current arrangement position of each IC specified by the user. The predicted EMI value indicates the amount of EMI radiation (intensity of electromagnetic radiation) from the entire printed circuit board, or both the amount of EMI radiation and the direction of EMI radiation (direction of electromagnetic radiation). For example, a graph indicating the distribution of the EMI radiation amount (distribution of the magnitude of the combined vector) corresponding to each of 50 frequency bands (FB1 to FB50) is a design of the display device 13 as a predicted value (evaluation value) of electromagnetic radiation. Displayed on the screen.

  The designer can change the placement position on the printed circuit board where each IC is to be placed by operating the input device 11 while viewing the predicted value of the EMI radiation amount displayed on the design screen. Note that the component placement changing unit 139 may automatically correct the placement position of each IC so that the size of the combined vector (predicted value of the EMI radiation amount) is within an allowable value.

  Although it is preferable that the predicted value of the EMI radiation amount be within an allowable value for all frequency bands, attention is paid only to a specific frequency band such as the frequency band used by the high-speed signal interface. The arrangement position may be modified so that only the predicted value of the EMI radiation amount corresponding to the specific frequency band falls within the allowable value.

  Instead of the above-described graph, an object such as an arrow that visually indicates the size and direction of each composite vector may be displayed on the design screen.

  Next, the procedure of the component placement support process executed by the design support program will be described with reference to the flowchart of FIG.

  First, the design support program reads the LSI model information from the storage device 122, and calculates the value of the current flowing from each driver (each output pin) of each IC for each frequency band based on the read LSI model information ( Step S101). Next, the design support program reads, for example, pin information and connection information from the storage device 122. Then, the design support program, based on the pin information and the connection information, all the output pins (driver pins) and all of all the ICs (or some ICs having a large current value) mounted on the printed circuit board. Input pins (receiver pins) are extracted, and the direction of current is determined for each extracted output pin (step S102). In step S102, for example, the direction of the straight line from the output pin to the connection destination input pin is determined as the direction of the current flowing from the output pin. Next, the design support program calculates the value of the current flowing from each output pin and the current vector indicating the direction of the current for each frequency band (step S103).

  Thereafter, the design support program calculates a combined vector indicating the sum of current vectors corresponding to the same frequency band for each frequency band, and prints based on the calculated size of the combined vector of each frequency band. A predicted value of electromagnetic radiation of the entire circuit board is output (step S104). For example, a graph indicating the distribution of the magnitude of the combined vector corresponding to each of the frequency bands FB1 to FB50 is displayed on the design screen of the display device 13 as a predicted value (evaluation value) of electromagnetic radiation of the entire printed circuit board. Further, the design support program compares the predicted value of electromagnetic radiation with an allowable value, and determines whether or not the predicted value of electromagnetic radiation exceeds the allowable value (step S105). If the predicted value of electromagnetic radiation exceeds the allowable value, the design support program executes a process for changing the IC placement position (step S106).

  As described above, in the design support apparatus of this embodiment, the amount of EMI radiation of the entire printed circuit board due to the current component placement is calculated (simplely) at the component placement stage, and the calculation result is It is possible to evaluate or optimize the position of each IC. Therefore, it is possible to support the arrangement positions of the ICs on the printed circuit board in consideration of the reduction of EMI radiation.

  In addition, since the main current direction (the direction of EMI radiation) can be detected for each frequency band by the combined vector, the position on the printed circuit board where EMI countermeasures should be taken is specified based on the direction of the EMI radiation. You can also

  Since all the functions of the design support apparatus of this embodiment are realized by a computer program, the computer program can be installed in a normal computer through a computer-readable storage medium storing the computer program. The same effect as that of the embodiment can be easily realized.

  Further, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine a component suitably in different embodiment.

  DESCRIPTION OF SYMBOLS 11 ... Input device, 12 ... System main body, 13 ... Display device, 121 ... Main processing part, 122 ... Storage device, 131 ... Input processing part, 132 ... Component arrangement processing part, 133 ... Current calculation part, 134 ... Current direction determination 135, current vector calculation unit, 136 ... composite vector calculation unit, 137 ... EMI evaluation unit, 138 ... display processing unit, 139 ... component placement change unit.

Claims (8)

A designation means for designating a position on a printed circuit board on which each of a plurality of integrated circuits (ICs) is arranged according to an operation of the input device;
A storage device for storing model information of each IC and connection information indicating a connection relationship between pins of the plurality of ICs;
Current calculation means for calculating the value of the current flowing from each of the output pins of each of the plurality of ICs for each frequency band based on the model information;
Current direction determining means for determining a direction of a current flowing from each of the output pins based on the connection information and a designated position of each of the plurality of ICs;
Current vector calculation means for calculating a current vector indicating a value of a current flowing from each of the output pins and a direction of the current for each frequency band; and
A combined vector calculating means for calculating a combined vector indicating a sum of current vectors corresponding to the same frequency band for each frequency band;
A design support apparatus comprising: output means for outputting a predicted value of electromagnetic radiation of the printed circuit board based on the calculated magnitude of the combined vector of each frequency band.   The design support apparatus according to claim 1, wherein the output unit displays a predicted value of electromagnetic radiation of the printed circuit board on a display.   The design support apparatus according to claim 1, wherein the predicted value of the electromagnetic radiation of the printed circuit board indicates a distribution of the magnitude of the combined vector corresponding to each of the frequency bands.   The current direction determining means determines, for each of the output pins, a direction of a straight line connecting the output pin and an input pin to which the output pin is connected as a direction of current flowing from the output pin. The design support apparatus according to claim 1. A design support method for supporting the design of a product including a printed circuit board by a computer,
A designation step for designating a position on the printed circuit board where each of a plurality of integrated circuits (ICs) is arranged in accordance with an operation of an input device of the computer;
A current calculation step of calculating a value of a current flowing from each output pin of each of the plurality of ICs for each frequency band based on model information of each IC stored in a storage device of the computer;
A current direction for determining a direction of a current flowing from each of the output pins based on connection information indicating a connection relation between pins of the plurality of ICs stored in the storage device and a position of each of the designated ICs; A decision step;
A current vector calculation step of calculating a current vector indicating a value of a current flowing from each of the output pins and a direction of the current for each frequency band; and
A combined vector calculation step for calculating a combined vector indicating a sum of current vectors corresponding to the same frequency band for each frequency band; and
An output step of outputting a predicted value of the electromagnetic radiation of the printed circuit board based on the calculated magnitude of the combined vector of each frequency band.   6. The design support method according to claim 5, wherein the output step displays a predicted value of electromagnetic radiation of the printed circuit board on a display of the computer.   The design support method according to claim 5, wherein the predicted value of the electromagnetic radiation of the printed circuit board indicates a distribution of magnitudes of the combined vectors corresponding to the frequency bands.   In the current direction determining step, for each output pin, a direction of a straight line connecting the output pin and an input pin to which the output pin is connected is determined as a direction of current flowing from the output pin. The design support method according to claim 5.

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