JP2007140839A - Printed circuit board design support device, printed circuit board design support method and printed circuit board design-support program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress unnecessary electromagnetic radiation generated with a cable as an antenna caused by voltage fluctuation between a power supply and a ground plane of a printed circuit board. <P>SOLUTION: This printed circuit board design support device has: a power supply-ground plane end part cell extraction part 5 dividing a layout of a power supply-ground plane of layout information of a design target printed circuit board connected with the cable into one or more cells, and extracting only a peripheral cell (a cell including a power supply plane end part) of the layout of the power supply-ground plane; a transmission admittance calculation part 8 calculating a transmission admittance that is a relation between a current induced to the cable and the voltage fluctuation of each frequency in the power supply-ground plane end part cell to a power supply current characteristic of an LSI at switching time of the LSI mounted on the board; and an electric field intensity calculation part 10 calculating an electric field intensity radiated from the cable on the basis of the calculated transmission admittance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printed circuit board design support apparatus, a printed circuit board design support method, and a printed circuit board design support program for a printed circuit board that can suppress unnecessary electromagnetic radiation from a connected cable.

  A printed circuit board on which an LSI or IC is mounted emits unnecessary electromagnetic waves. Since this unnecessary electromagnetic radiation causes a malfunction in other electronic devices, it is necessary to suppress the radiation intensity to a value smaller than the value determined by the standard. In addition, to avoid the need to change the design to suppress unwanted electromagnetic radiation or add countermeasure parts after the printed circuit board is manufactured, measure the electrical characteristics at the design stage to prevent unwanted electromagnetic radiation. It is necessary to take.

  There are circuit analysis methods such as SPICE and electromagnetic field analysis methods such as the FDTD method, the moment method, and the finite element method as methods for analyzing the electrical characteristics of the printed circuit board, which are widely used in the design of printed circuit boards. ing.

  By the way, the cable connected to the printed circuit board itself operates as an antenna, and generates a high level of unnecessary electromagnetic radiation.

Since radiation from this cable is caused by a common mode current flowing through the cable, it is necessary to use an analysis method that can handle the common mode current in order to calculate unwanted electromagnetic radiation.

  Here, a circuit analysis method such as SPICE cannot handle a common mode current. For this reason, the unwanted electromagnetic radiation from the cable cannot be calculated. On the other hand, electromagnetic field analysis methods such as the FDTD method and the moment method can handle common mode currents. However, in general, it takes an enormous amount of time to model an entire printed circuit board including a cable and perform an electromagnetic field analysis. For this reason, it is not practical to use it for the purpose of calculating unnecessary electromagnetic radiation from the cable at the design stage of the printed circuit board or examining the suppression measures.

Based on the above, in order to suppress unnecessary electromagnetic radiation at the design stage of the printed circuit board, an analysis method that can calculate unnecessary electromagnetic radiation from the cable in a short time, and a printed circuit that suppresses unnecessary electromagnetic radiation from the cable There is a need for a substrate design method.

  As a printed circuit board design method for suppressing unnecessary electromagnetic radiation from such a cable, there is a technique disclosed in Patent Document 1. In Patent Document 1, the electronic device, wiring, and ground plane are converted into an electromagnetic field analysis model from the printed circuit board layout information, and the distribution of the electric field strength generated near the ground plane as the electronic device operates is calculated. is doing. And the unnecessary electromagnetic radiation from a cable is suppressed by connecting a cable to the part with this weak electric field strength. As described above, Patent Document 1 obtains a design guideline that suppresses unnecessary electromagnetic radiation from a cable in a short time by simplifying a printed circuit board and performing an electromagnetic field analysis using an analysis model that does not include a cable. It was. In relation to the above technology, the following reports have been made.

  In the “electromagnetic field strength calculating device” disclosed in Japanese Patent Application Laid-Open No. 7-234890, each device of the electric circuit device to be analyzed in the electromagnetic field strength calculating device that calculates the electromagnetic field strength radiated by the electric circuit device. The section is divided into a device part to which the distributed constant line approximation method can be applied and a device part to which the distributed constant line approximation method is not applicable, and a distribution is performed with respect to the device part that the section means (11) classifies as applicable. By applying the constant line approximation method, the first calculation means (12) for calculating the current distribution of the device portion and the current distribution calculated by the first calculation means (12), the sorting means (11) Is applied to a device part that is classified as unapplicable, whereby a second calculation means (13) for calculating a current distribution of the device part and a current calculated by the first calculation means (12) Distribution and second calculation And a current distribution calculating stage (13), the electromagnetic field intensity calculation apparatus and a third calculation means for calculating the electromagnetic field intensity (14) for radiating the electric circuit device has been proposed.

  In addition, in the “electromagnetic field strength calculating device” disclosed in Japanese Patent Application Laid-Open No. 7-302278, in the electromagnetic field strength calculating device for calculating the electromagnetic field strength radiated by the electric circuit device based on the moment method, the electric circuit device According to the structure of the input circuit (10) for accurately inputting the structure of the printed boards / cables / leads / metal casings of the electronic circuit board and the structure of the electric circuit device to be input by the input means (10) / Derivation means for deriving simultaneous equations of the moment method with unknown currents flowing in cables / leads / metal casings and equivalent currents and equivalent magnetic currents flowing in dielectrics of printed boards and other types (111) and the simultaneous equations of the moment method derived by the deriving means (111), the current flowing in the printed boards / cables / leads / metal casings, and the printed board A calculation means (112) for calculating an equivalent current and an equivalent magnetic current flowing in a dielectric having a class or another class, and an electromagnetic field intensity radiated by the electric circuit device from a calculation value calculated by the calculation means (112). There has been proposed an electromagnetic field intensity calculating device including a calculating means (113) for calculating.

  In addition, in “a recording medium storing a program having an electromagnetic field intensity calculating device, an electromagnetic field intensity calculating method, and an electromagnetic field intensity calculating unit” disclosed in Japanese Patent Laid-Open No. 11-161690, input data is set. An electromagnetic field radiated from the electrical circuit device based on the analysis input data obtained based on the model obtained by the model creation unit. A navigation file storing a plurality of procedures including at least a procedure for inputting an outer dimension of an electric circuit device and a procedure for inputting an analysis frequency for meshing and analyzing the electric circuit device; Display means for sequentially displaying the procedures stored in the navigation file, and display on the display means Electromagnetic field intensity calculation apparatus utilized in accordance with the procedures is to set the input data interactively that has been proposed.

JP 2001-318961 A JP-A-7-234890 JP-A-7-302278 Japanese Patent Laid-Open No. 11-161690

  A path through which a current causing unnecessary electromagnetic radiation flows in a cable connected to the printed circuit board includes a common mode current flowing through the ground plane and a voltage fluctuation between the power supply and the ground plane. In Patent Document 1, unnecessary electromagnetic radiation generated from the cable due to the common mode current flowing through the ground plane can be suppressed, but unnecessary electromagnetic radiation due to voltage fluctuation between the power source and the ground plane is suppressed. I can't.

  An object of the present invention is to provide a printed circuit board that can be used for designing a printed circuit board that suppresses unnecessary electromagnetic radiation generated by using a cable as an antenna due to voltage fluctuation between a power source and a ground plane of the printed circuit board. The object is to provide a design support apparatus, a printed circuit board design support method, and a printed circuit board design support program.

  In the following, means for solving the problem will be described using reference numerals with parentheses used in [Best Mode for Carrying Out the Invention]. These symbols are added in order to clarify the correspondence between the description of [Claims] and the description of the best mode for carrying out the invention. ] Should not be used for interpretation of the technical scope of the invention described in the above.

  The printed circuit board design support apparatus of the present invention is a printed circuit board design support apparatus (1) for obtaining the electric field strength of unnecessary electromagnetic waves radiated from a cable (140) connected to a printed circuit board to be designed. Among the layout information of the printed circuit board to be connected to the cable, one or a plurality of cells (120) has a power-ground layout composed of the power plane (101) and the ground plane (100). Power supply-ground cell generation unit (4) and power supply-ground system edge cell extraction that extracts only the cell including the edge (103) of the power plane among one or a plurality of divided cells Part (5) and the power supply current characteristics of the LSI when switching the LSI mounted on the printed circuit board to be designed. A transfer admittance calculation unit (8) for calculating a transfer admittance that is a relationship between a voltage variation at each clock frequency of the LSI in the cell including the end of the power plane and a current induced in the cable, and the calculated transfer admittance And an electric field intensity calculation unit (10) for calculating the electric field intensity of the unnecessary electromagnetic wave radiated from the cable.

  A printed circuit board design support apparatus according to the present invention is a printed circuit board design support apparatus (1) for predicting the electric field strength of unnecessary electromagnetic radiation in a printed circuit board to which a cable (140) is connected. A printed circuit board layout information input unit (2) for inputting the layout information of the circuit board, and of the printed circuit board layout information, a power-ground layout comprising a power plane (101) and a ground plane (100) A power source-ground system layout extraction unit (3) to extract, a power source-ground system cell generation unit (4) that divides the power source-ground system layout into one or a plurality of cells, and a cell including an end of the power plane Power supply-ground system end cell extraction unit (5) that extracts only, and mounted on the printed circuit board An LSI power supply current characteristic input unit (6) for inputting a value of a current flowing in the power supply system at the time of switching of the LSI, and an LSI power supply current characteristic input unit at a clock frequency involved in the operation of the LSI and an integer multiple thereof. A power-ground voltage fluctuation calculation unit (7) for calculating voltage fluctuation for each LSI clock frequency in a cell including the end of the power plane of the printed circuit board based on the value of the current flowing in the power supply system; A transfer admittance calculation unit (8) for calculating a transfer admittance that is a relationship between a voltage variation for each LSI clock frequency in a cell including the end of the power plane and a current induced in the cable; and an end of the power plane A cable that calculates the current induced in the cable based on the voltage in the containing cell and the calculated transfer admittance A flow calculation unit (9), a radiation field strength calculation unit (10) for calculating the field strength radiated from the cable from the current flowing in the cable, and a field strength display unit for displaying the calculated radiation field strength for each frequency (11).

  Further, the radiation electric field intensity calculation unit (10) in the printed circuit board design support apparatus (1) of the present invention emits from the cable (140) when the printed circuit board is composed of a plurality of power-ground systems. The electric field strength is calculated for each power-ground system.

  Further, the transfer admittance calculation unit (8) in the printed circuit board design support device (1) of the present invention converts the voltage in the cell (120) including the end of the power plane of the printed circuit board to the ground plane (100) or the cable ( 140) is converted into a common mode voltage and the transfer admittance is calculated.

  In the printed circuit board design support apparatus (1) of the present invention, the voltage in the cell including the end portion (103) of the power plane of the printed circuit board and the common mode voltage on the ground plane (100) or the cable (140). The conversion coefficient is 0.5.

  In the printed circuit board design support apparatus (1) of the present invention, the voltage in the cell including the end portion (103) of the power plane of the printed circuit board and the common mode voltage on the ground plane (100) or the cable (140). The conversion coefficient is any value from 0.35 to 0.7.

  The printed circuit board design support apparatus (21) of the present invention further includes a layout information changing unit (12) for changing the layout information of the printed circuit board.

  The printed circuit board design support apparatus (21) of the present invention further includes a transmission admittance storage unit (13) for storing the transmission admittance.

  The printed circuit board design support method of the present invention is a printed circuit board design support method for determining the electric field strength of unnecessary electromagnetic waves radiated from a cable (140) connected to a printed circuit board to be designed. Among the layout information of the printed circuit board to be connected to the cable, the power-ground layout composed of the power plane (101) and the ground plane (100) is assigned to one or a plurality of cells (120). A power-ground system cell generation step for dividing, a power-ground system end cell extraction step for extracting only the cell including the end portion (103) of the power plane among one or a plurality of divided cells, and design When switching the LSI mounted on the target printed circuit board, the power supply current characteristics of the LSI A transfer admittance calculating step for calculating a transfer admittance that is a relationship between a voltage variation for each clock frequency of the LSI in a cell including an end of the power plane and a current induced in the cable, and based on the calculated transfer admittance And an electric field intensity calculating step for calculating an electric field intensity of an unnecessary electromagnetic wave radiated from the cable.

  Further, in the printed circuit board design support method of the present invention, when the printed circuit board is composed of a plurality of power supply-ground systems, a power supply-ground system cell generation step, a power supply-ground system end cell extraction step, The electric field intensity radiated from the cable (140) is calculated for each power-ground system by the transfer admittance calculating step and the electric field intensity calculating step.

  Further, in the printed circuit board design support method of the present invention, the transfer admittance calculation step uses the voltage in the cell including the end (103) of the power plane of the printed circuit board as a common on the ground plane (100) or the cable (140). Convert as mode voltage and calculate transfer admittance.

  Further, in the printed circuit board design support method of the present invention, the conversion coefficient between the voltage in the cell including the end (103) of the power plane of the printed circuit board and the common mode voltage on the ground plane (100) or the cable (140). Is 0.5.

  Further, in the printed circuit board design support method of the present invention, the conversion coefficient between the voltage in the cell including the end (103) of the power plane of the printed circuit board and the common mode voltage on the ground plane (100) or the cable (140). Is any value from 0.35 to 0.7.

  The printed circuit board design support method of the present invention further includes a transmission admittance storage step for storing the calculated transmission admittance, and when the transmission admittance is the same before and after the layout information change of the printed circuit board, Recalculate the voltage fluctuation in the cell including the end of the power plane, and based on the recalculated voltage fluctuation and the stored transmission admittance, the electric field intensity calculation step calculates the electric field intensity of the unwanted electromagnetic wave radiated from the cable. calculate.

  The printed circuit board design support program of the present invention can be read by a computer, and realizes the printed circuit board design support method according to any one of claims 9 to 14.

  According to the present invention, a printed circuit board printed circuit board capable of suppressing unnecessary electromagnetic waves radiated by using a cable connected to the printed circuit board as an antenna due to voltage fluctuation between a power source and a ground plane of the printed circuit board. A board design support device, a printed circuit board design support method, and a printed circuit board design support program can be provided.

  Hereinafter, a printed circuit board design support apparatus, a printed circuit board design support method, and a printed circuit board design support program according to the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 shows functional blocks of a printed circuit board design support apparatus 1 according to Embodiment 1 of the present invention. The circuit board design support apparatus 1 according to the first embodiment has, as its functional configuration, a printed circuit board layout information input unit 2 to which printed circuit board layout information is input, and a power-ground system based on the layout information. A power source-ground system layout extraction unit 3 for extracting a layout to be generated, a power source-ground system cell generation unit 4 for dividing the power source-ground system layout into one or a plurality of cells, and peripheral cells of the power source-ground system layout Power supply-ground system end cell extraction section 5 for extracting only the power, LSI power supply current characteristic input section 6 representing the current flowing in the power supply system at the time of LSI switching, and the clock frequency involved in the operation of this LSI and its integral multiple frequency In the power supply-ground system end cell for the power supply current characteristics of LSI A power supply-ground system voltage fluctuation calculation unit 7 that calculates voltage fluctuations of the wave number, and a transmission admittance calculation unit 8 that calculates transmission admittance that is a relationship between the voltage fluctuations in the power supply-ground system end cell and the current induced in the cable. A cable current calculation unit 9 that calculates the current induced in the cable using the voltage of the power-ground system end cell and the transfer admittance, and an electric field strength calculation unit 10 that calculates the radiation electric field strength from the current flowing in the cable, And an electric field intensity display unit 11 for displaying the obtained electric field intensity for each frequency.

  FIG. 21 shows a hardware configuration for realizing the functional blocks according to the present embodiment. The design support apparatus 31 shown in FIG. 21 includes a printed circuit board design support program or a recording medium 32 in which various data necessary for calculation in the design support program are stored, and a design support apparatus main body 33. . The recording medium 32 includes power source / ground system layout extraction, power source / ground system cell generation, power source / ground system end cell extraction, power source / ground system voltage fluctuation calculation, transfer admittance calculation, cable current A program used for calculation and calculation of the radiation electric field strength is stored. The design support device main body 33 includes an input / output device 34 for inputting / outputting data, a storage device 35 for storing a program or data read from the recording medium 32, an arithmetic device 36 for performing overall control and calculation, and a calculation. A display device 37 for displaying the results is provided, and these are connected to each other by a bus 38. The printed circuit board layout information input unit 2 and the LSI power supply current characteristic input unit 6 described above are provided in the input / output device 34. In addition, the power source / ground system layout extraction unit 3, the power source / ground system cell generation unit 4, the power source / ground system end cell extraction unit 5, the power source / ground system voltage fluctuation calculation unit 7, the transfer admittance calculation unit 8, and the cable current calculation The unit 9 and the radiated electric field intensity calculation unit 10 are provided in the arithmetic device 36, respectively. The radiated electric field intensity display unit 11 is a display device 37. In the hardware configuration described above, the layout information of the printed circuit board input to the storage device 35 via the bus 38 from the input device 34, the data relating to the power supply current characteristics of the LSI, and the program read from the recording medium 32 are used. The radiated electric field intensity from the cable is calculated by the arithmetic device 36 and the result is displayed on the display device 37.

(Operation principle of Embodiment 1)
Next, the operation of the printed circuit board design support apparatus 1 according to the first embodiment will be described with reference to FIG. FIG. 2 is a flowchart showing the operation of the present embodiment.

  When the printed circuit board design support apparatus 1 according to the present embodiment is activated, the arithmetic device 36 shown in FIG. 21 reads and executes programs stored in advance in the storage medium 32 and the storage device 35. Thereby, each functional block shown in FIG. 1 is realized by the arithmetic unit 36. After the printed circuit board design support device 1 is activated, the printed circuit board includes the structure of the power plane and the ground plane, the mounting position of electronic devices such as LSI and IC and the decoupling capacitor, the structure of the cable to be connected, and the connection position. Is input from the printed circuit board layout information input unit 2 (step S10), and is output to the power-ground layout extraction unit 3. The power supply / ground layout extraction unit 3 extracts a layout related to the power supply plane 101-ground plane 100 and the dielectric substrate 110 from the data relating to the layout of the printed circuit board as shown in FIG. 3 (step S11). The data is output to the power-ground cell generator 4. In the power supply-ground system cell generation unit 4, one or a plurality of power supply planes 101-ground planes 100 are arranged based on layout information related to the power supply plane 101-ground plane 100 and the dielectric substrate 110, as shown in FIG. The data is divided into cells 120 (step S12), and the data is output to the power system end cell extraction unit 5. Although the dielectric substrate 110 is not illustrated in FIG. 4, the dielectric substrate 110 is also divided into cells in the same manner. The power supply system end cell extraction unit 5 extracts the cell at the power supply / ground plane end 103 shown in FIG. 4 (step S13), and outputs the data to the power supply voltage fluctuation calculation unit 7. Here, as shown in FIG. 5, when the end portions of the power plane 101 and the ground plane 100 overlap, as shown by the dotted line in FIG. It is not included in the cell 103. However, as shown by a circle in the figure, when the portion where the ends of both planes overlap includes the cable connecting portion 130, this cell is handled as a cell of the power-ground plane end 103.

なお、プリント回路基板に電源プレーンが２つ以上存在する場合には、ケーブルに流れる電流を電源−グラウンドプレーン対ごとに算出し、それぞれを電界強度算出部１０に出力する。 The power supply voltage fluctuation calculation unit 7 converts the power supply current waveform associated with LSI switching output from the LSI power supply current characteristic input unit 6 and the power supply-ground system data output from the power supply end cell extraction unit 5. Based on the clock frequency involved in the operation of the LSI and an integer multiple thereof, the power supply voltage fluctuation VDM (i) in each cell i at each end of the power supply system is calculated (step S14), and the data is transmitted to the transfer admittance calculation unit. 8 is output. The voltage fluctuation can be calculated in a short time by using a technique in which the power supply-ground plane is expressed by an equivalent circuit and is calculated by a circuit simulator such as SPICE. The transfer admittance calculation unit 8 uses the analysis model in which the cable 140 is connected to the cell-divided ground plane 100 as shown in FIG. 6, and the voltage VDM in each cell i at the end of the power-ground plane by a method described later. (I) and a transfer admittance Y (i, j) which is a relation between currents induced at one or a plurality of current observation points j provided on the cable is calculated (step S15), and the data is calculated as a cable current calculation unit. Output to 9. The cable current calculation unit 9 flows from the transfer admittance Y (i, j) and the voltage fluctuation VDM (i) at the power supply-ground system end output from the power supply voltage fluctuation calculation unit to the current observation point j on the cable. The current ICM (i, j) is obtained. Based on Equation 1, the voltage observation point i is summed to calculate the current ICABLE (j) flowing through the current observation point j (step S16), and the result is output to the electric field strength calculation unit 10.

When there are two or more power supply planes on the printed circuit board, the current flowing through the cable is calculated for each power supply-ground plane pair, and each is output to the electric field strength calculation unit 10.

  The electric field strength calculation unit 10 calculates the radiated electric field strength from the current distribution flowing through the cable (step S17), and outputs the result to the electric field strength display unit 11. When there are two or more power planes on the printed circuit board, the radiated electric field strength due to the voltage fluctuation of each power-ground plane pair is calculated individually, and all the power-ground plane pairs summed up are calculated. The radiation electric field intensity resulting from the voltage fluctuation is also calculated.

ここで、ηは周囲媒質のインピーダンスであり、空間の誘電率、透磁率をそれぞれε、μとして、

で表される。 Here, a method for calculating the radiated electric field intensity from the current distribution in the electric field intensity calculation unit 10 will be described. The electromagnetic field radiated to the surroundings by a current element of length Δz and current I arranged at the origin of the coordinate system shown in FIG. 7 is shown in many literatures on electromagnetism, for example, Kai Fong Lee According to the book “PRINCIPLES of ANTENNA THEORY” (John Wiley & Sons, 1984, pp. 27-31), it is expressed by Equation 2.

Where η is the impedance of the surrounding medium, and the permittivity and permeability of the space are ε and μ, respectively.

It is represented by

電界強度算出部１０では、ケーブル上の観測点ｊにおいて間隔Δ（ｊ）でサンプリングした電流から、プリント回路基板レイアウト上の任意の点を原点とし、電流の方向、各電流観測点から原点および放射電界強度観測点との距離を考慮し、上述した微小電流素片が発生する電磁界に関する式を用いて放射電界強度を計算する。これをケーブルに沿って積分することにより、任意形状のケーブルからの放射電界強度を算出することができる。また、このような計算方法を使用することにより、プリント回路基板からの放射を除外し、ケーブルからの放射電磁界のみを計算することができる。電界強度表示部１１では、電界強度算出部１０で計算されたケーブルからの放射電界強度を表示する。プリント回路基板に電源プレーンが２つ以上ある場合には、各電源−グラウンドプレーン対の電圧変動に起因する放射電界強度を個別に表示するとともに、これらを合計した全ての電源−グラウンドプレーン対の電圧変動に起因する放射電界強度も表示する（ステップＳ１８）。 Further, j is an imaginary unit, κ is a wave number, and r is a distance from the origin to the observation point of the electromagnetic field. Further, when the observation point of the electromagnetic field satisfies κr >> 1, [Equation 2] can be approximated by the following [Equation 4].

The electric field strength calculation unit 10 uses an arbitrary point on the printed circuit board layout as an origin from the current sampled at the interval Δ (j) at the observation point j on the cable, and the current direction, the origin and the radiation from each current observation point. In consideration of the distance to the field strength observation point, the radiation field strength is calculated using the above-described formula relating to the electromagnetic field generated by the minute current element. By integrating this along the cable, the radiated electric field intensity from the cable having an arbitrary shape can be calculated. Also, by using such a calculation method, it is possible to exclude radiation from the printed circuit board and calculate only the radiated electromagnetic field from the cable. The field strength display unit 11 displays the radiation field strength from the cable calculated by the field strength calculation unit 10. When there are two or more power planes on the printed circuit board, the radiated electric field strength due to the voltage fluctuation of each power source-ground plane pair is individually displayed, and the voltage of all power source-ground plane pairs summed up. The radiated electric field intensity resulting from the fluctuation is also displayed (step S18).

  By using such a display method, a designer can identify power-ground plane pairs that produce more radiated electric fields. For this reason, it becomes possible to preferentially take countermeasures from the power supply-ground plane pair that contributes to radiation, and the design can be made more efficient.

このグラウンドプレーン上に発生したコモンモード電圧ＶＣＭ（ｉ）と、ケーブルに流れる電流ＩＣＭ（ｉ）の関係をアドミタンスＹＣＭ（ｉ）とすると、これらの関係は［数式６］で表される。したがって、電圧ＶＤＭ（ｉ）とアドミタンスＹ（ｉ）の関係は［数式７］で表すことができる。

伝達アドミタンス算出部８では、電源−グラウンドプレーン端部の各セルｉにおける伝達アドミタンスＹＣＭ（ｉ）を算出し、比例係数Ｋを乗じたデータをケーブル電流算出部９に出力する。ここではグラウンドプレーンとケーブルのみで構成される簡易な解析モデルでアドミタンスを算出できるため、プリント回路基板全体をモデル化するよりも解析に要する時間を大幅に短縮できる。ここで、比例係数Ｋは理論的に求められていないため、本発明では以下に示す方法で数値実験的にその値を決定した。 Here, in the transfer admittance calculation unit 8, the voltage VDM (i) in each cell i at the end of the power supply-ground plane and the current ICM (i) flowing through the cable (in this case, provided on the cable for simplicity of explanation) The method for calculating the transfer admittance Y (i) representing the relationship of the current observation point j will be described. First, as shown in FIG. 8, a voltage VDM (i) generated at the end of the power-ground plane causes a common mode current to be generated on the conductor in a direction perpendicular to the boundary 103a at the end of the power-ground plane. An induced common mode voltage VCM (i) is generated. That is, the common mode voltage VCM (i) is generated in the ground plane 100 in FIG. 8A and in the cable 140 connected to the ground plane in FIG. This relationship is expressed by [Formula 5] as a proportional coefficient K.

If the relationship between the common mode voltage VCM (i) generated on the ground plane and the current ICM (i) flowing through the cable is admittance YCM (i), these relationships are expressed by [Formula 6]. Therefore, the relationship between the voltage VDM (i) and the admittance Y (i) can be expressed by [Formula 7].

The transmission admittance calculation unit 8 calculates the transmission admittance YCM (i) in each cell i at the end of the power-ground plane, and outputs the data multiplied by the proportional coefficient K to the cable current calculation unit 9. Here, since the admittance can be calculated with a simple analysis model composed of only a ground plane and a cable, the time required for the analysis can be greatly reduced compared to modeling the entire printed circuit board. Here, since the proportionality coefficient K is not theoretically obtained, in the present invention, the value was determined by numerical experiment by the following method.

  FIG. 9 is an electromagnetic field analysis model of a printed circuit board to which a cable created to determine the proportionality coefficient K is connected. The substrate size of the dielectric substrate 110 was 100 mm × 100 mm × 3 mm. As the substrate material of the dielectric substrate 110, FR-4 (glass epoxy substrate) is assumed, and the relative dielectric constant thereof is set to 4.3. The power plane 101 was 50 mm × 50 mm, the ground plane 100 was 100 mm × 100 mm, and the power-ground plane interval was 1 mm. A cable 140 having a diameter of 0.1 mm and a length of 500 mm was connected to the ground plane. At the signal input position 150 shown in the drawing of this analysis model, a voltage source having an internal resistance of 1Ω was connected as a wave source for inducing voltage fluctuations in the power supply-ground system, and 1 W of power was supplied. This analysis model was simulated by the FDTD method, and the current ICABLE flowing through the connection portion of the cable to the ground plane was observed every 25 MHz up to 1 GHz.

以上により算出したＩＣＡＢＬＥとＩＣＭの絶対値の差が最小となるよう、最小自乗法により比例係数Ｋを決定した。また、図１１、図１２に示すように、電源プレーンの配置位置を変化させた解析モデルにおいても同様の解析を行った。さらに、電源−グラウンドプレーン間隔を０．５ｍｍとして、計６種類の解析モデルにおいて同様の解析を行った。 Next, the cable was removed from the analysis model shown in the figure, and a simulation was performed using the analysis model of only the power supply system, and the voltage VDM (i) at the end of the power supply-ground plane was observed at intervals of 5 mm. Next, in order to calculate YCM (i) which is the relationship between the common mode voltage VCM (i) on the ground plane and the current flowing through the cable, an analysis model including the ground plane 100 and the cable 140 divided into cells shown in FIG. It was created. Using this analysis model, the relationship YCM (i) between the common mode voltage VCM (i) at the position corresponding to the end of the power supply-ground system and the current flowing through the cable was calculated every 25 MHz up to 1 GHz by the moment method. Then, using VDM (i) obtained in the previous analysis, the current ICM flowing through the connection portion of the cable to the ground plane was calculated by [Equation 8].

The proportionality coefficient K was determined by the method of least squares so that the difference between the absolute values of ICABLE and ICM calculated above was minimized. Further, as shown in FIGS. 11 and 12, the same analysis was performed on an analysis model in which the position of the power plane is changed. Furthermore, the same analysis was performed on a total of six types of analysis models, with the distance between the power supply and the ground plane being 0.5 mm.

  As a result, for these three types of power plane arrangements, the values of K are 0.52, 0.49, and 0.48 when the power-ground plane spacing is 1 mm, and the power-ground plane spacing is At 0.5 mm, the values were 0.49, 0.47, and 0.49. The calculation results of the currents ICABLE and ICM flowing through the cable at this time are shown in FIGS. In these figures, the solid line indicates ICABLE and the dotted line indicates ICM, and both are well matched including the frequency characteristics. From these results, it was found that K has a value of about 0.5 without depending on the thickness of the power-ground plane. Further, if K is 0.5, the error with respect to the calculated K value (0.47 to 0.52) is within 0.6 dB, and the current flowing through the cable can be calculated with sufficiently high accuracy. it can. Furthermore, considering that the measurement result usually has a fluctuation range of about 3 dB in the EMI measurement, it is desirable that K is in the range of 0.35 to 0.7.

  According to the printed circuit board design support apparatus according to the present embodiment, due to voltage fluctuation between the power supply and the ground plane of the printed circuit board, unwanted electromagnetic radiation using the cable as an antenna is reduced at the end of the power supply and ground system. The calculation is divided into a step for calculating voltage fluctuation, a step for calculating transfer admittance representing the relationship between the voltage variation and the current induced in the cable, and a step for calculating the radiated electric field intensity from the current induced in the cable. . Each of these processes can be calculated in a shorter time than an electromagnetic field analysis method in which a printed circuit board and a cable are modeled and calculated integrally. For this reason, it is possible to confirm the effects of measures such as the arrangement of decoupling capacitors to suppress voltage fluctuations between the power supply and the ground plane and changes in the structure of the power supply and ground plane in a short time. A printed circuit board with suppressed radiation can be designed.

(Embodiment 2)
A printed circuit board design support apparatus according to Embodiment 2 of the present invention will be described. FIG. 19 shows functional blocks of the printed circuit board design support apparatus 21 according to the present embodiment. 19, the same functional blocks as those of the printed circuit board design support apparatus 1 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. As shown in FIG. 19, the printed circuit board design support apparatus 21 according to the present embodiment changes the printed circuit board layout for changing the layout information of the printed circuit board to the printed circuit board design support apparatus 1 shown in FIG. 1. Functional units such as an information change unit 12 and a transfer admittance storage unit 13 that stores the transfer admittance calculated by the transfer admittance calculation unit 8 are added. The printed circuit board layout information changing unit 12 changes information related to the layout of the printed circuit board output from the printed circuit board layout information input unit 2 and outputs the data to the power-ground layout extraction unit 3. The transmission admittance storage unit 13 stores the transmission admittance calculated by the transmission admittance calculation unit 8, and in the layout information change performed by the printed circuit board layout information change unit 12, the structure of the power supply-ground plane, the structure of the cable, If there is no change in the data regarding the cell size for dividing the connection position and the power-ground plane, it is provided to omit the process of calculating the transfer admittance again.

  The hardware configuration of the printed circuit board design support apparatus according to the present embodiment is as shown in FIG. 21 as in the first embodiment. In the present embodiment, the printed circuit board layout information changing unit 12 is provided in the input / output device 34, and the transfer admittance storage unit 13 is provided in the storage device 35. Other configurations are the same as those in the first embodiment, and thus are omitted.

(Operation Principle of Embodiment 2)
Next, the operation of the printed circuit board design support apparatus 21 according to the second embodiment will be described with reference to FIG. FIG. 20 is a flowchart showing the operation of the present embodiment.

  When the printed circuit board design support device 21 according to the present embodiment is activated, the arithmetic device 36 shown in FIG. 21 reads and executes a program stored in advance in the storage medium 32 and the storage device 35. Thereby, each functional block shown in FIG. 19 is realized by the arithmetic unit 36. After the printed circuit board design support device 21 is activated, it relates to the layout of the printed circuit board such as the structure of the power plane and ground plane, the mounting position of electronic devices such as LSI and IC and decoupling capacitors, the structure and connection position of the cable, etc. Data is input to the printed circuit board layout information input unit 2 (step S20) and output to the printed circuit board layout information change unit 12. The printed circuit board layout information change unit 12 suppresses voltage fluctuations in the power supply-ground system, the structure of the power supply plane and the ground plane, the mounting position of electronic devices such as LSI and IC and decoupling capacitors, the structure of the cable, The layout information is changed, such as changing the connection position or adding a decoupling capacitor (step S21), and the data is output to the power-ground layout information extraction unit 3. The power supply / ground system layout extraction unit 3 extracts a layout related to the power supply / ground system from the data relating to the layout of the printed circuit board (step S22), and outputs the data to the power supply / ground system cell generation unit 4. The power supply / ground system cell generation unit 4 divides the power supply / ground system into one or a plurality of cells based on the layout information regarding the power supply / ground system (step S23), and the data is stored in the power supply end cell extraction unit 5. Output to. The power system end cell extraction unit 5 extracts a cell at the end of the power supply-ground plane (step S24), and outputs the data to the power supply voltage fluctuation calculation unit 7. The power supply voltage fluctuation calculation unit 7 is based on the data on the power supply current waveform accompanying the switching of the LSI output from the LSI power supply current characteristic input unit 6 and the data on the power supply-ground system output from the power supply system end cell extraction unit. Thus, the fluctuation of the power supply voltage in each cell at the power supply system end is calculated at the clock frequency involved in the operation of the LSI and the integer multiple thereof (step S25), and the data is output to the transfer admittance calculation unit 8.

  The transfer admittance used in the printed circuit board design support apparatus of the present invention divides the power plane and ground plane structure, cable structure or connection position, and power-ground plane even if the layout information of the printed circuit board is changed. If the cell size is not changed, the same data can be used before and after the layout information is changed. The transfer admittance calculation unit 8 confirms whether or not the same data can be used, and thereby determines whether it is necessary to calculate the transfer admittance (step S26). When the transfer admittance calculation unit 8 determines that the calculation is necessary, the transfer admittance calculation unit 8 determines the transfer admittance that is the relationship between the voltage at each cell at the end of the power supply-ground plane and the current induced in the cable. Is calculated (step S27), and the data is output to the transmission admittance storage unit 13 and the cable current calculation unit 9 (step S34). On the other hand, when the transfer admittance stored in the transfer admittance storage unit 13 can be used, the step of calculating the transfer admittance is omitted, the data in the transfer admittance storage unit 13 is read (step S33), and the cable current calculation is performed. Is output to the unit 9. As apparent from the step of calculating the transfer admittance by the transfer admittance calculation unit 8 described above, the structure of the power plane and ground plane, the structure or connection position of the cable, and the cell size for dividing the power-ground plane are the same. If so, the analysis model for calculating the transfer admittance is the same, and thus the calculated transfer admittance is also the same. When the printed circuit board layout information changing unit 12 changes an electronic component such as an LSI or IC, a mounting position of a decoupling capacitor, or a change in which these components are added, a cell that divides a power-ground plane If the sizes are the same, there is no need to calculate the transfer admittance again, and the data stored in the transfer admittance storage unit 13 can be used again. For this reason, the time for calculating the radiation electric field intensity from the cable is greatly shortened.

  Next, the cable current calculation unit 9 calculates the current flowing through the cable from the transfer admittance output from the transfer admittance calculation unit 8 and the voltage fluctuation at the power supply-ground system end output from the power supply voltage fluctuation calculation unit 7. (Step S28), and the result is output to the electric field strength calculation unit 10. The electric field intensity calculation unit 10 calculates the radiated electric field intensity from the current distribution on the cable (step S29), and outputs the result to the electric field intensity display unit 11. The electric field strength display unit 11 displays the radiated electric field strength from the cable calculated by the electric field strength calculation unit 10 (step S30). Based on the radiated electric field intensity displayed on the electric field intensity display unit 11, it is determined whether or not the layout needs to be changed (step S31). Then, when it is determined that the radiation field intensity is sufficiently suppressed, all the steps are finished. On the other hand, when it is determined that the radiated electric field intensity is not sufficiently suppressed, the layout information of the printed circuit board is changed back to step S21, and the processes from step S22 to step S31 are performed. Is called.

  With the above flow configuration, in order to suppress the electric field intensity radiated from the cable, the structure of the power plane and ground plane, the mounting position of the electronic device such as LSI and IC and the decoupling capacitor, etc. are connected. It becomes possible to change the structure and connection position of the cable. Further, before and after the layout information is changed, when the power plane or ground plane structure, the cable structure or connection position, and the cell size for dividing the power-ground plane are the same, the transmission stored in the transmission admittance storage unit 13 is stored. By using the admittance, it is possible to calculate the intensity of the electric field radiated from the cable in a short time.

  Thus, by providing the printed circuit board layout information changing unit 12, it is possible to take measures to suppress the intensity of the radiated electric field from the cable. Furthermore, by providing the transfer admittance storage unit 13, the calculation of the radiated electric field strength can be greatly shortened so that the effect of the countermeasure for suppressing the radiated electric field strength can be confirmed in a short time, thereby suppressing unnecessary electromagnetic radiation. Printed circuit boards can be designed.

(Example)
Next, an embodiment in which the present invention is applied to specific printed circuit board layout information will be described. FIG. 22 is a perspective view (a) and a top view (b) schematically showing a printed circuit board which is a subject of the present embodiment. In this example, using the printed circuit board design support apparatus 1 according to the first embodiment, the radiated electric field intensity from the cable 140 was calculated for the printed circuit board on which one LSI shown in FIG. 22 is mounted.

  First, in the printed circuit board layout information input unit 2 of the printed circuit board design support apparatus 1, the size of the printed circuit board is 200 mm × 200 mm × 1.5 mm, the relative permittivity of the substrate material of the dielectric substrate 110 is 4.3, and the power plane 101 size 100 mm × 150 mm, ground plane 100 size 200 mm × 200 mm, power supply-ground plane spacing 0.5 mm, cable diameter 0.1 mm, length 1 m, and their positional relationship and LSI mounting position 200 The layout information shown is input. Next, the power supply current characteristic of the LSI operating at 20 MHz shown in FIG. 23 is input. FIG. 23A shows the characteristics of the power supply current generated along with the operation of the LSI, with time on the horizontal axis and current value on the vertical axis. FIG. 23B is a graph obtained by converting the time waveform of the power supply current shown in FIG. 23A into the frequency domain. And the radiation electric field strength from a cable was computed by the calculation process (step S17) of the radiation electric field strength in Embodiment 1 mentioned above. Here, the maximum electric field strength at a point 3 m away from the center of the cable was calculated, and the result was displayed on the radiated electric field strength display unit 11 as shown in FIG. In FIG. 24, the horizontal axis represents the frequency, the vertical axis represents the maximum value of the radiated electric field intensity, and the radiated electric field intensity from the cable with respect to the input power supply current characteristic of the LSI is shown. According to FIG. 24, it can be seen that the electric field intensity radiated from the cable 140 is maximum at a frequency that is an integral multiple of the LSI operating frequency of 20 MHz.

It is a figure which shows the function structure of the printed circuit board design assistance apparatus concerning Embodiment 1 of this invention. It is a figure which shows the operation | movement flow of the printed circuit board design assistance apparatus concerning Embodiment 1 of this invention. It is a figure for demonstrating the positional relationship of the power supply plane-ground plane of a printed circuit board. It is a figure for demonstrating the positional relationship of each cell division | segmentation of a power supply plane-ground plane of a printed circuit board, and a power plane plane edge part-ground plane edge part, (a) is a perspective view, (b) shows a top view. . It is a figure for demonstrating the positional relationship of a power plane end part-a ground plane end part, (a) is a perspective view, (b) shows a top view. It is a figure for demonstrating the analysis model of transmission admittance. It is a figure for demonstrating the radiation electric field from a microcurrent element piece. It is a figure for demonstrating the common mode voltage which generate | occur | produces with the voltage which arises between a power plane plane edge part-a ground plane edge part, (a) is generated on a ground plane, (b) generates a common mode voltage on a cable. FIG. It is a figure which shows the analysis model of the printed circuit board for determining the proportionality coefficient K showing the relationship between the voltage produced between a power plane plane edge part-a ground plane edge part, and a common mode voltage, (a) is a perspective view, ( b) shows a top view. FIG. 10 is a diagram illustrating an analysis model for calculating transfer admittance that is a relationship between a common mode voltage generated on the ground plane and a current flowing in the cable in the printed circuit board of FIG. 9. FIG. 10 is a top view showing an analysis model in which the arrangement of power planes is changed in the printed circuit board of FIG. 9. FIG. 10 is a top view showing an analysis model in which the arrangement of power planes is changed in the printed circuit board of FIG. 9. It is the figure which compared the electric current which flows through a cable in order to determine the proportionality coefficient K using the printed circuit board shown in FIG. FIG. 11 is a diagram comparing currents flowing in cables in the arrangement of the power supply plane shown in FIG. 10 in order to determine the proportionality coefficient K using the printed circuit board shown in FIG. 9. FIG. 12 is a diagram comparing the current flowing through the cable in the arrangement of the power supply plane shown in FIG. 11 in order to determine the proportionality coefficient K using the printed circuit board shown in FIG. 9. FIG. 10 is a diagram comparing the current flowing in the cable with the distance between the power plane and the ground plane being 0.5 mm in order to determine the proportionality coefficient K using the printed circuit board shown in FIG. 9. FIG. 11 is a diagram comparing the current flowing through the cable with the space between the power supply plane and the ground plane being 0.5 mm in the arrangement of the power supply plane shown in FIG. 10 in order to determine the proportionality coefficient K using the printed circuit board shown in FIG. 9. FIG. 12 is a diagram comparing the current flowing in the cable with the space between the power plane and the ground plane being 0.5 mm in the arrangement of the power plane shown in FIG. 11 in order to determine the proportionality coefficient K using the printed circuit board shown in FIG. 9. It is a block diagram which shows the structure of the printed circuit board design assistance apparatus concerning Embodiment 2 of this invention. It is a flowchart which shows operation | movement of the printed circuit board design assistance apparatus concerning Embodiment 2 of this invention. It is a figure which shows the hardware constitutions of the printed circuit board design assistance apparatus of this invention. It is a figure which shows the printed circuit board used in the Example of this invention. It is a figure which shows the characteristic in the (a) time domain of the LSI power supply current used in the Example of this invention, and the characteristic in the (b) frequency domain. It is a figure which shows the radiation electric field intensity | strength from the cable calculated in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 21 ... Printed circuit board design support apparatus 2 ... Printed circuit board layout information input part 3 ... Power supply-ground system layout extraction part 4 ... Power supply-ground system cell generation part 5 ... Power supply system end cell extraction part 6 ... LSI power supply Current characteristic input unit 7 ... power supply voltage fluctuation calculation unit 8 ... transmission admittance calculation unit 9 ... cable current calculation unit 10 ... electric field strength calculation unit 11 ... electric field strength display unit 12 ... printed circuit board layout information change unit 13 ... transmission admittance storage unit 31 ... Design support device 32 ... Recording medium 33 ... Design support device main body 34 ... Input / output device 35 ... Storage device 36 ... Computing device 37 ... Display device 100 ... Ground plane 101 ... Power plane 103 ... Power supply-ground plane end 103a ... Power supply-ground plane edge boundary line 110 ... dielectric substrate 120 ... divided cell 130 ... cave Connection point 140 ... cable 150 ... signal input location 200 ... LSI mounting position

Claims (15)

A printed circuit board design support device for determining the electric field strength of an unnecessary electromagnetic wave radiated from a cable connected to a printed circuit board to be designed,
Among the layout information of the printed circuit board that is the design target to which the cable is connected, the power source composed of the power plane and the ground plane—the power source that divides the ground layout into one or more cells—the ground cell generator ,
A power source-ground system end cell extracting unit that extracts only cells including the end of the power plane among the one or a plurality of divided cells;
At the time of switching of the LSI mounted on the printed circuit board that is the design target, the voltage fluctuation for each LSI clock frequency in the cell including the end of the power supply plane corresponding to the power supply current characteristic of the LSI and the cable A transfer admittance calculating unit that calculates a transfer admittance that is a relationship with the induced current;
A printed circuit board design support device comprising: an electric field strength calculation unit that calculates an electric field strength of an unnecessary electromagnetic wave radiated from the cable based on the calculated transfer admittance. A printed circuit board design support apparatus for predicting the electric field strength of unnecessary electromagnetic radiation in a printed circuit board to which a cable is connected,
A printed circuit board layout information input unit for inputting printed circuit board layout information;
A power supply-ground layout extraction unit that extracts a power-ground layout including a power plane and a ground plane out of the printed circuit board layout information;
A power-ground cell generator for dividing the power-ground layout into one or a plurality of cells;
A power source-ground system end cell extraction unit that extracts only cells including an end of the power plane; and
An LSI power supply current characteristic input unit for inputting a value of a current flowing in the power supply system at the time of switching of the LSI mounted on the printed circuit board;
Based on the value of the current flowing through the power supply system that is input from the LSI power supply current characteristic input unit at a clock frequency involved in the operation of the LSI and a frequency that is an integral multiple of the clock frequency, the power plane of the printed circuit board A power supply-ground voltage fluctuation calculating section for calculating voltage fluctuation for each clock frequency of the LSI in a cell including an end; and
A transmission admittance calculating unit that calculates a transmission admittance that is a relationship between a voltage variation for each clock frequency of the LSI in a cell including an end of the power plane and a current induced in the cable;
A cable current calculation unit that calculates a current induced in the cable based on a voltage in a cell including an end of the power plane and the calculated transfer admittance;
From the current flowing through the cable, a radiated electric field strength calculating unit that calculates the electric field strength radiated from the cable,
A printed circuit board design support apparatus, comprising: an electric field intensity display unit that displays the calculated radiated electric field intensity for each frequency.   The radiated electric field intensity calculation unit calculates the radiated electric field intensity from the cable for each of the power supply-ground systems when the printed circuit board includes a plurality of power supply-ground systems. Item 3. A printed circuit board design support apparatus according to Item 2.   The transfer admittance calculation unit converts a voltage in a cell including an end of the power plane of the printed circuit board as a common mode voltage on the ground plane or the cable, and calculates the transfer admittance by the transfer admittance calculation unit. The printed circuit board design support apparatus according to claim 2, wherein the printed circuit board design support apparatus is configured as described above.   The printed circuit board according to claim 4, wherein a conversion coefficient between a voltage in a cell including an end of the power plane of the printed circuit board and a common mode voltage on the ground plane or the cable is 0.5. Circuit board design support device.   A conversion coefficient between a voltage in a cell including an end portion of the power plane of the printed circuit board and a common mode voltage on the ground plane or the cable has a value of 0.35 to 0.7. The printed circuit board design support apparatus according to claim 4.   The printed circuit board design support apparatus according to claim 2, further comprising a layout information changing unit for changing layout information of the printed circuit board.   The printed circuit board design support apparatus according to claim 2, further comprising a transmission admittance storage unit that stores the transmission admittance. A printed circuit board design support method for obtaining the electric field strength of unnecessary electromagnetic waves radiated from a cable connected to a printed circuit board to be designed,
Among the layout information of the printed circuit board that is the design target to which the cable is connected, the power source composed of the power plane and the ground plane—the power source that divides the ground layout into one or more cells—the ground cell generation step, ,
A power-ground system end cell extraction step for extracting only the cell including the end of the power plane among the one or a plurality of divided cells;
At the time of switching of the LSI mounted on the printed circuit board that is the design target, the voltage fluctuation for each LSI clock frequency in the cell including the end of the power supply plane corresponding to the power supply current characteristic of the LSI and the cable A transfer admittance calculating step for calculating a transfer admittance that is a relationship with the induced current;
A printed circuit board design support method comprising: an electric field strength calculation step of calculating an electric field strength of an unnecessary electromagnetic wave radiated from the cable based on the calculated transfer admittance.   When the printed circuit board includes a plurality of power supply-ground systems, the power supply-ground system cell generation step, the power supply-ground system end cell extraction step, the transfer admittance calculation step, and the electric field strength 10. The printed circuit board design support method according to claim 9, wherein the calculation step calculates an electric field intensity radiated from the cable for each power supply-ground system.   The transfer admittance calculating step converts the voltage in a cell including an end of the power plane of the printed circuit board as a common mode voltage on the ground plane or the cable, and calculates the transfer admittance. The printed circuit board design support method according to claim 9.   The printed circuit board according to claim 11, wherein a conversion coefficient between a voltage in a cell including an end portion of the power plane of the printed circuit board and a common mode voltage on the ground plane or the cable is 0.5. Circuit board design support method.   A conversion coefficient between a voltage in a cell including an end portion of the power plane of the printed circuit board and a common mode voltage on the ground plane or the cable has a value of 0.35 to 0.7. The printed circuit board design support method according to claim 11. Furthermore, a transmission admittance storage step for storing the calculated transmission admittance is provided,
When the transfer admittance is the same before and after the layout information change of the printed circuit board, the voltage variation in the cell including the end of the power plane is recalculated, and the recalculated voltage variation is stored. The printed circuit board design support according to any one of claims 9 to 13, wherein the electric field intensity calculation step calculates an electric field intensity of an unnecessary electromagnetic wave radiated from the cable based on the transmission admittance. Method.   A printed circuit board design support program for causing a computer to realize the printed circuit board design support method according to any one of claims 9 to 14.

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