JPH1115870A - Printed board design supporting system and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display the effective range of a by-pass capacitor on a printed board in each power supply used for the printed board on a power supply area in each sort of the power supply. SOLUTION: In the case of plotting the effective range of a bypass capacitor for a selected power supply on a screen as an ellipse, a by-pass capacitor arrangement evaluation tool 12 finds out AND between the effective range and a power supply area and executes plotting processing so that the effective range is displayed only in the power supply area. Since the effective range of a part stuck out from the power supply area is not plotted, an ellipse is not displayed on two or more power supplies even when plural power supplies are simultaneously displayed, so that the effective ranges of by-pass capacitors for respective power supplies can be easily and precisely grasped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board design support system and a printed circuit board design CA having a function of evaluating the arrangement of bypass capacitors on a printed circuit board.
The present invention relates to a recording medium applied to the D system.

Further, the present invention provides a printed circuit board design C for designing a layout of a circuit board constituting an electronic circuit.
In an AD system, the present invention relates to a printed board design support system having a function of evaluating a bypass capacitor arranged on a board, and a recording medium.

[0003]

2. Description of the Related Art In electronic equipment including a microprocessor, such as a computer system, a clock signal of a high frequency band or various signals synchronized therewith is supplied to a signal path on a multilayer circuit board to a CPU and its peripheral circuits. Input and output.

In a circuit board operating at a high frequency, a method of inserting a bypass capacitor into the entire board is generally used as a main means for suppressing radiation noise and power supply noise, which are particularly serious problems. Used.

On the other hand, in recent years, a so-called printed board design CAD (computer aided design) utilizing a computer has been used for a layout design for forming an electronic circuit on a circuit board.
) System is used.

With this printed circuit board design CAD system, it is necessary to determine the effective location of the bypass capacitor in designing the board layout. Traditionally,
In this case, the location of the bypass capacitor is determined based on the experience of the layout designer. That is, conventionally, there is no means for easily grasping the characteristics of the individual bypass capacitors and the characteristics of the local plane layer on the substrate, so that it is measured after the initial design to determine whether the noise suppression effect is sufficient. Confirmation was made, and if it was not enough, the setting was made by repeating trial and error, such as correcting the arrangement location. For this reason, conventionally, the time required for the circuit board layout design becomes enormous, and as a result, the efficiency of the CAD system is not always utilized.

Therefore, in order to evaluate whether or not the placement of the bypass capacitor is appropriate at the stage of the board layout design, the effective range of the bypass capacitor is approximated from the wiring shape of the bypass capacitor on the screen of the printed circuit board design CAD. It is desired to realize a function of calculating and displaying a circle. This allows
By designing the circle so as to cover the entire substrate, the user can take measures against radiation noise by a bypass capacitor related to the power supply and the ground.

However, at this time, when a plurality of power supply areas exist on one substrate, the following inconvenience occurs. That is, the bypass capacitor is generally effective only for one connected power supply. Here, if a circle is drawn across multiple power supply areas, the range drawn on the unconnected power supply area is invalid, even if the circle seems to cover the entire board at first glance, Not exist. Therefore, the user of the display function determines which circle is valid for which power supply area, but the number of bypass capacitors is large,
When the circles overlap, there is a problem that it is practically difficult.

[0009]

As described above, in order to evaluate whether or not the arrangement of the bypass capacitors is appropriate at the stage of the board layout design, the printed circuit board design C is required.
When trying to realize the function of approximately calculating the effective range from the wiring shape of the bypass capacitor on the AD screen and displaying it in a circle, when there are multiple power supply areas on one board, Then, even if the circles seem to cover the whole board, there is a malfunction where some parts do not, and if there are many bypass capacitors and the circles overlap, which circle is which power supply area However, there is a problem that the effective range of the bypass capacitor for each power supply on the board cannot be clearly recognized.

The present invention has been made in view of the above circumstances,
In a computer-aided design system having a function of evaluating the arrangement state of bypass capacitors on a printed circuit board, a printed circuit board design support system and a printed circuit capable of clearly recognizing an effective range of a bypass capacitor for each power supply on the board. An object of the present invention is to provide a recording medium applied to a board design CAD system.

Further, the present invention provides a printed circuit board design C for designing a layout of a circuit board constituting an electronic circuit.
In the AD system, the performance evaluation related to the location of the bypass capacitor at the time of circuit board layout design can be visually grasped for each power supply, so that the location of the bypass capacitor for each power supply can be determined efficiently. An object of the present invention is to provide a printed circuit board design support system and a recording medium having a bypass capacitor evaluation function that can be performed.

Further, the present invention relates to a printed circuit board design support system having a function of evaluating the arrangement state of bypass capacitors on a printed circuit board. Is displayed in the power supply area for each power supply type, so that the effective range of the bypass capacitor for each power supply can be clearly and easily recognized, and the layout location can be determined efficiently. It is an object to provide a recording medium applied to a system and a printed circuit board design CAD system.

Further, the present invention provides a printed circuit board design support system having a function of evaluating an arrangement state of bypass capacitors on a printed circuit board, wherein the effective range of the bypass capacitor is indicated by a circle for each power supply present on the board. By displaying the circle only inside the target power area,
A printed circuit board design support system and print that can provide an environment in which the effective range of a bypass capacitor for each power supply area can always be correctly and easily grasped even when a plurality of power supplies are present on one board. An object of the present invention is to provide a recording medium applied to a board design CAD system.

[0014]

SUMMARY OF THE INVENTION The present invention provides a printed circuit board design CAD system for designing a layout of a circuit board constituting an electronic circuit, a means for determining an effective range of a bypass capacitor depending on an arrangement place, Display means for visually displaying the determined effective range of the bypass capacitor in units of power supply is provided.

More specifically, a bypass capacitor placement evaluation tool (software) provided in a printed circuit board design CAD system utilizes board layout information necessary for circuit board layout design, and supplies a bypass capacitor for each power supply. Determine the parameters for the wiring path of
The effective range of the bypass capacitor for each power supply is determined from the impedance characteristics calculated based on these parameters. The parameters relating to the wiring path of the bypass capacitor include the wiring length, the resistivity, the wiring width, and the wiring thickness of the wiring path of the bypass capacitor. Furthermore, the tool displays the determined effective range of the bypass capacitor for each power supply as an approximate ellipse on a display screen in units of power supply.

By using a printed circuit board design CAD system having such a function, the layout designer of the circuit board calls and executes a placement evaluation tool for a bypass capacitor, thereby displaying on the screen of the display. The effective range of the bypass capacitor for each power supply can be visually confirmed as an approximate ellipse. Therefore, without repeating trial and error such as actual measurement after design,
The effective range of the bypass capacitor for each power supply can be easily grasped.

That is, the present invention is a printed circuit board design support system having a function of evaluating an arrangement state of a bypass capacitor interposed in a power supply circuit on a printed circuit board.
Means for calculating the effective range of a bypass capacitor on a printed circuit board based on input information including printed circuit board layout information, printed circuit board structure and material information, and signal name information indicating the type of each power supply handled by the printed circuit board. Means for displaying the list in a selectable manner, and means for displaying the effective range of the bypass capacitor on the printed circuit board of the power supply according to the selected signal name information. The effective range of the bypass capacitor in the above is displayed.

The present invention is also a printed circuit board design support system having a function of evaluating an arrangement state of a bypass capacitor interposed in a power supply circuit on the printed circuit board. Means for calculating the effective range of the bypass capacitor on the printed circuit board based on the input information including the material information; means for selectively displaying a list of signal name information indicating the type of each power supply handled by the printed circuit board; Means for displaying the effective range of the bypass capacitor on the printed circuit board of the power supply according to the signal name information provided only within the area of the power supply. The effective range of the bypass capacitor is displayed in the power supply area for each power supply type.

Further, the present invention is characterized in that in the printed circuit board design support system, the input information includes impedance information indicating an effective range designated by a user.

Further, the present invention is a printed circuit board design support system for performing a printed circuit board layout design, wherein the circuit board layout information storage means stores board layout information necessary for the printed circuit board layout design, Means for determining a parameter relating to a wiring path of a bypass capacitor for noise removal arranged on the printed circuit board based on the board layout information, and determining an effective range of the bypass capacitor from impedance characteristics calculated based on the parameter; Display means for displaying the effective range of the bypass capacitor on the screen of the display so that the effective range of the bypass capacitor can be visually confirmed while being limited only within the area of the target power supply. Visually only within the area of the target power supply Characterized in that it can be checked in.

Further, the present invention, in the printed circuit board design support system, has a calculating means for calculating the effective range of the bypass capacitor as an approximate ellipse, and the approximate ellipse calculated by the calculating means corresponds to the approximate area. It is characterized by being visually displayed in the power supply area.

Further, according to the present invention, in the above-mentioned printed circuit board design support system, the effective range of the bypass capacitor on the printed circuit board for each of the power supplies handled by the board is different from the display color for each unit impedance or each power supply type. Is visually displayed.

The present invention is also directed to a machine-readable recording medium applied to a printed circuit board design CAD system, wherein the printed circuit board design CAD system includes printed circuit board layout information, printed circuit board structure and material information, and user information. Procedure to calculate effective range of bypass capacitor on printed circuit board based on input information with impedance information indicating effective range according to designation, selectable list of signal name information indicating each type of power supply handled on printed circuit board A program for executing a procedure for displaying and a procedure for generating display data for displaying an effective range of the bypass capacitor on the printed circuit board of the power supply according to the selected signal name information is recorded, and the printed circuit board design CA is recorded.
The D system is characterized in that the effective range of the bypass capacitor on the printed circuit board can be displayed for each type of power supply handled by the board.

The present invention is also directed to a machine-readable recording medium applied to a printed circuit board design CAD system, the printed circuit board layout information, the printed circuit board structure and material information, and the impedance indicating the effective range specified by the user. The procedure to calculate the effective range of the bypass capacitor on the printed circuit board based on the input information with the information, the procedure to selectably display the list of signal name information indicating the type of each power supply handled by the printed circuit board, A program for executing a procedure for generating display data for displaying the effective range of the bypass capacitor on the printed circuit board of the power supply according to the signal name information only in the area of the power supply, and records the program for printing the printed circuit board. The effective range of the bypass capacitor on each printed circuit board for each power supply And displaying on the power area.

Further, the present invention includes a program for executing a procedure for calculating an effective range of a bypass capacitor as an approximate ellipse in the above-mentioned machine-readable recording medium, wherein the approximate range calculated by the procedure is calculated. The ellipse is visually displayed in a corresponding power supply area.

By using a printed circuit board design support system or a machine-readable recording medium having a function of evaluating the arrangement of bypass capacitors on a printed circuit board according to the present invention, each power supply on the printed circuit board is The effective range of the bypass capacitor can be clearly recognized.

Further, in a printed circuit board design CAD system for designing a circuit board layout, it is possible to visually grasp the performance evaluation related to the location of the bypass capacitor for each power supply when designing the printed circuit board layout.
Thereby, it is possible to efficiently determine the location of the bypass capacitor for each power supply.

Further, the effective range of the bypass capacitor on the printed circuit board of each power supply handled by the board is displayed in the power supply area for each type of power supply, thereby clearly defining the effective range of the bypass capacitor for each power supply. In addition, it can be easily recognized, and the location can be determined efficiently.

Further, the effective range of the bypass capacitor is displayed by a circle for each power supply present on the board, and the circle is displayed only inside the target power supply area, so that a plurality of power supplies are present on one board. Even in such a case, it is possible to provide an environment in which the effective range of the bypass capacitor for each power supply area can always be correctly and easily grasped.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram showing main system components according to an embodiment of the present invention.

In the figure, 11 is a printed circuit board design CA
Board layout C which is the basic tool (main element) of D
An AD processing unit 12 is a bypass capacitor arrangement evaluation tool that forms a part of the board layout CAD processing unit 1.

This bypass capacitor arrangement evaluation tool 1
2 includes a power supply table (T) for managing the type of power supply used (V / G pair) for each printed circuit board as shown in FIG.
A), a bypass capacitor effective range information table (T) for managing information indicating the effective range of the bypass capacitor for each power supply.
B), a bypass capacitor effective range calculation processing routine (PA) shown in FIG. 5 for each power supply, and a bypass capacitor effective range display processing routine (P shown in FIG. 6)
B) and the like.

Reference numeral 13 denotes an operation input unit for transferring user input information to the decapsulation placement evaluation tool 12, for example, impedance information (x) indicating an effective range desired by the user.
Ω) and various input information such as the designation of a power supply area to be displayed are transferred to the decapsulation placement evaluation tool 12.

A parameter input unit 14 for inputting various parameters set by the user, for example, by a data card, is used for setting coefficients of an equation for calculating a radius of a circle indicating an effective range of the bypass capacitor. You.

Reference numeral 15 denotes a storage unit for storing layout information of a board. Here, board data including data (coordinate value data) indicating the shape of a power supply area for each board, a layer structure for each board, Library information including data for simulation such as thickness and material of the library is stored.

Reference numeral 16 denotes a display control unit for controlling the display output of various board information including the pattern layout of the wiring layer handled in the printed board design CAD. In this case, for a designated power supply area, a bypass capacitor is provided for each area. Is displayed on the display unit 18 of the CAD.

Reference numeral 17 denotes a wiring rule violating capacitor list display control unit for controlling the display output of a list of bypass capacitors violating the wiring rule. Here, an effective range calculating routine (P) for each power supply shown in FIG.
A list of capacitors that have been checked in the wiring rule violation in A) is displayed and controlled on the display unit 18 of the CAD.

Reference numerals 18A and 18B denote effective range display screens of bypass capacitors which are selectively displayed and output on the display unit 18 of the CAD. The effective range display screen of the power supply area according to the instruction of the operation input unit 13 is selectively displayed. Is output. In this embodiment, as shown in the figure, the effective range of the bypass capacitor on each printed circuit board of each power supply handled by the printed circuit board is only within the power supply area for each type of power supply (exposed from the corresponding power supply area). (With the circle cut out and removed).

FIG. 2 is an explanatory diagram of the overall operation in the embodiment of the present invention. Here, when designation information (power signal name) of a power supply area to be displayed is input from the operation input unit 13, the bypass capacitor arrangement evaluation tool 12 displays a power supply according to the designation information on the power supply table (TA). A signal name (here, a +5 V power supply) is selected, and from the signal name of this power supply, elliptical information indicating an effective range of each bypass capacitor of the power supply is extracted on a bypass capacitor effective range information table (TB). Along with
Data indicating the shape of the power supply area is extracted from the board data storage unit of the storage unit 15. Then, elliptical data for display (elliptical pattern data) is generated in accordance with the elliptical information indicating the effective range of each of the bypass capacitors, and the portion of the elliptical pattern that protrudes from the power area is based on the shape data of the power area. After being deleted, the effective range of each of the bypass capacitors of the designated power supply is displayed in an elliptical pattern in the power supply area.

FIG. 3 shows an example of the configuration of the bypass capacitor display setting panel in the above embodiment. Here, the effective range of each bypass capacitor is displayed as a plurality of concentric circles (ellipses) with different impedance values. And a selector (circle 1, circle 2,...) For designating the number of circles to be displayed. In addition, the type of power supply (signal name; + 5V, B3V, B5V, etc.) for each board is displayed in a selectable list.

FIG. 4 is a diagram showing an algorithm for displaying the effective range of the bypass capacitor for each power supply in the above embodiment. FIG. 5 is a flowchart showing a bypass capacitor effective range calculation processing routine (PA) for each power supply in the above embodiment.

FIG. 6 is a flowchart showing a bypass capacitor effective range display processing routine (PB) in the above embodiment. FIGS. 7 to 9 are operation principle diagrams for explaining the processing operation when the effective range of the bypass capacitor is drawn as an approximate ellipse in the embodiment of the present invention. The algorithm for calculating the diameter of the ellipse for the mounted bypass capacitor will be described with reference to FIGS. FIG. 7A is an image of Z1, FIG.
(B) shows the impedance characteristics. FIG.
In (A), Z1 is defined as the impedance of a wiring path between a power supply cell VCC to which a bypass capacitor is connected and a ground cell GND. Here, the power supply / ground cell is a hole for electrically connecting the power supply layer / ground layer and the wiring. The parameters for determining Z1 are: a). Wiring length L between power supply cell / ground cell (sum of wiring length of power supply cell and ground cell to which bypass capacitor is connected), b). Resistivity a0 (equivalent resistivity of the line connecting the capacitor and the cell), c). Wiring width W,
d). The wiring thickness T is four. Power cell-Any point A-
Let Z2 be the equivalent impedance on the plane layer up to the ground cell. This value is given as a function of the distance L2 from point C to point A, as shown in FIGS. 7 (C) and 8 (A). a). Sum L of distances from arbitrary point A to each cell
2 (total distance from point B to point B via A). b).
Impedance characteristic a1 (a constant indicating the characteristic of the impedance of the plane layer).

Then, the sum of the impedances Z = Z1 +
A distance L2 such that Z2 becomes Za ohm is obtained, and this is drawn as a half of the diameter of the ellipse, and an ellipse is drawn with the power cell and the ground cell as the focal points of the ellipse. Similarly, the same calculation is performed for Zb, Zc, and Zd, and a color-coded display provides a display that is easy for the user to see (see FIG. 8C). The user uses the inner circle for areas where noise constraints are relatively tight,
In addition, the arrangement of the bypass capacitors can be evaluated by using the outer circle in a relatively less severe area.

FIG. 10 shows a case where the effective area of the bypass capacitor is drawn as an ellipse, by cutting out the portion exposed from the power supply area (in this case, cutting off the portion exposed by taking an AND with the power supply area). FIG. 9 is a diagram illustrating a case and a case where the drawing is performed without performing the cut processing,
FIG. 7A shows a case where the above-described cut processing is performed, and FIG. 7B shows a case where the above-described cut processing is not performed.

The operation in the embodiment of the present invention will now be described with reference to the above-mentioned drawings. First, the principle of drawing the effective range of the bypass capacitor as an approximate ellipse will be described with reference to FIGS.

Here, as shown in FIG. 7A, it is assumed that a bypass capacitor C is disposed in a wiring path between a power supply cell VCC having a wiring length L1 and a ground cell GND. The impedance Z1 of this wiring path is determined by the wiring length L1, the resistivity a0, the wiring thickness t, and the capacitance of the bypass capacitor C. Here, the resistivity a0 is expressed as a slope between L1 and Z1, as shown in FIG. 7B. Further, as shown in FIG. 8A, a predetermined distance L
3 and L4, an equivalent impedance Z2 on the plane layer is assumed (see FIG. 8B). This equivalent impedance Z2 is given as a function of the sum L2 of the distances from the arbitrary point A to each cell. This L2 is “L2 = L3 + L4”.

From the relationship between the impedance Z2 and the distance L2, an impedance characteristic a1 that can be expressed as a slope can be determined as shown in FIG. Then, when the sum of the impedances Z1 and Z2 is Z, L2 corresponding to the sum Z of the impedances is obtained, and this is set to half the diameter of the ellipse (elliptical portion), as shown in FIG. Then, an ellipse having the ellipse as a focus on the power cell VCC and the ground cell GND is drawn. That is, a locus of the arbitrary point A is drawn such that Z2 is constant.

Next, the ellipse diameters rad1 to ra
A method of calculating the ellipses 1 to 4 corresponding to d4 will be described with a specific example. Z2 is determined by a1. When the length is x, it is expressed as “Z2 = f (x)”. This Z
Assuming that the resistance value of No. 2 is Z, ellipses 1 to 4 corresponding to diameters rad1 to rad4 are determined by the range as shown in FIG.

From the above “Z2 = f (x)”, the inverse function g is
“X = g (Z2)”. Also, "Z = Z1 + Z2"
From the above, “Z2 = Z−Z1” is obtained, and “x = g (Z−ZZ)
1) ”is required. Therefore, the diameters rad1 to rad4 can be calculated as shown in FIG.
FIG. 9B shows a specific calculation example.

For example, for the ellipse 4, L1 is set to “10 m
When "m" is set, rad4 is "3.475 cm" from the calculation example of FIG. 9B. From this, as shown in FIG. 9C, ± 1.
421 cm, ± 1.738 cm in the horizontal direction (= ± 3.4
An ellipse 4 inscribed in a rectangle of 75/2) can be drawn.

The board layout CAD processing section 11 is a basic tool (main element) of a printed circuit board design CAD, and has a bypass capacitor arrangement evaluation tool 12 according to the embodiment of the present invention as a part of the elements.

This bypass capacitor arrangement evaluation tool 1
2 includes a power supply table (T) for managing the type of power supply used (V / G pair) for each printed circuit board as shown in FIG.
A), a bypass capacitor effective range information table (T) for managing information indicating the effective range of the bypass capacitor for each power supply.
B), a bypass capacitor effective range calculation processing routine (PA) shown in FIG. 5 for each power supply, and a bypass capacitor effective range display processing routine (P shown in FIG. 6)
B) and the like.

Bypass capacitor arrangement evaluation tool 12
Receives various designated input information from the operation input unit 13, such as impedance information (xΩ) indicating an effective range desired by the user and designation of a power supply area to be displayed. Further, the parameter input unit 14 receives, for example, setting information of a coefficient of an equation for calculating a radius of a circle indicating an effective range of the bypass capacitor by the data card. Also, the storage unit 15 is accessed to simulate board data including data (coordinate value data) indicating the shape of the power supply area for each board, layer structure for each board, and thickness and material of each layer. And the like including library information.

A bypass capacitor arrangement evaluation tool 1
Reference numeral 2 controls display output of various board information including a pattern layout of a wiring layer handled by the printed board design CAD on the display section 18 of the CAD via the display control section 16. Here, display output control of the effective range display screens 18A and 18B of the power supply area according to the instruction of the operation input unit 13 is performed. At this time, the output of the ellipse indicating the effective range of the bypass capacitor to be displayed is restricted by the shape of the power supply area. Here, the AND of each ellipse indicating the effective range of the bypass capacitor displayed on the substrate and the shape of the power supply area is calculated, and the circle projected from the power supply area is cut out and removed.
Further, a list of bypass capacitors violating the wiring rule is displayed and output via the wiring rule violating capacitor list display control unit 17, but the details are omitted here.

The bypass capacitor arrangement evaluation tool 1
2, a list sub-window generating unit for generating a list screen of cell names of bypass capacitors for selection by an operator (user), a screen for changing parameters related to wiring paths of bypass capacitors, and the like, which are not shown, are searched by the operator. A wiring check unit and a wiring check unit that check a bypass capacitor having a cell name other than the excluded cell name and calculate the coordinates of the location of the target bypass capacitor, the wiring length L1 and the wiring width W of the wiring path, etc. Calculating a half of the diameter of the approximate ellipse indicating the effective range of the bypass capacitor by a predetermined algorithm based on parameters such as the wiring length L1 and the wiring width W of the wiring path calculated by the above and parameters set by the operator. , Four bypass capacitors on the editor screen It draws an ellipse, based on a predetermined wiring rules, extremely wiring is long bypass capacitors, etc., violation wiring check and so on for checking the bypass capacitor is provided by abnormal wiring that do not comply with wiring rules.

As shown in FIG. 7A, the bypass capacitor C is connected to a wiring path between the power supply cell VCC and the ground cell GND. The power cell VCC and the ground cell GND are holes for electrically connecting the power layer, the ground layer, and the wiring.

The list sub-window generating section generates a list display screen of the extracted bypass capacitor cell names and default values of various parameters, and displays the list on the CAD display section 18.
To be displayed. The list sub-window screen allows the operator to change parameters related to the wiring path of the bypass capacitor and to specify a bypass capacitor cell name that is not targeted.

The wiring check unit checks the bypass capacitor having a cell name other than the cell name excluded from the search by the operator, the coordinates of the location of the target bypass capacitor, the wiring length L1 and the wiring width W of the wiring path. Is calculated. Here, the wiring length L1 of the wiring path is the length of the wiring path between the power supply cell VCC and the ground cell GND as shown in FIG. The calculation unit calculates the diameter of the approximate ellipse indicating the effective range of the decap by a predetermined algorithm based on parameters such as the wiring length L1 and the wiring width W of the wiring path calculated by the wiring check unit and the parameters set by the operator. A half (rad1) is calculated, and further, rad1 to rad4 indicating four concentric ellipses are calculated. Here, the parameters of the calculation unit include the resistivity a
0, the wiring thickness t, and the like. The violation wiring check section
It is checked whether the target bypass capacitor satisfies a predetermined wiring rule. After such processing, the drawing unit draws the effective range of the target bypass capacitor as an approximate ellipse as shown in FIG.
For example, a concentric ellipse having a different effective range for each frequency parameter is drawn. From the display screen by the ellipse drawing of the effective range, the user can grasp the places on the substrate where the bypass capacitors are less effective or where the bypass capacitors are excessively arranged. The technology for displaying the effective range of the bypass capacitor by an ellipse is disclosed in detail in Japanese Patent Application No. 8-250553 (Computer Aided Design System).

Here, in the bypass capacitor arrangement evaluation tool 12, the effective range of the bypass capacitor on the printed circuit board of each power supply handled by the printed circuit board is set for each type of power supply only within the power supply area (from the power supply area). The operation of the display function corresponding to the multiple power supply for displaying the cut-out circle (notched and removed) will be described.

The power supply area to be displayed is specified on the CAD sub-window. When calculating the effective range, the power / ground signal names are extracted and a table thereof is created.

Then, a list is displayed on a list panel (bypass capacitor display setting panel) as shown in FIG. The user selects a target power supply area from the list and presses an end button.

By this operation, only the effective range of the capacitors of the bypass capacitors connected to the selected power supply area is to be drawn. The display algorithm at this time is shown in FIG.
Shown in

Here, when the effective range of the target bypass capacitor is drawn as an ellipse on the screen, it is displayed by ANDing the power supply area. By doing so, as shown in FIG. 10 (A), the effective range of the portion beyond the power supply area (extruded) is not drawn, and two ellipses are displayed even when a plurality of power supplies are displayed at the same time. Since the information is not displayed across the above power supplies, the effective range of the bypass capacitor of each power supply can be easily and accurately grasped. Note that FIG. 10B shows a case where the AND is not taken (the cut processing is not performed).

Here, in the embodiment of the present invention, the effective range calculation processing routine (P
The processing operation according to A) will be described with reference to FIG. In the process of calculating the effective range of the bypass capacitor for each power supply, a power supply area to be displayed is selected from a power supply signal name list (see FIG. 3) displayed on the display 18 of the CAD according to the power supply table (TA). By doing so, a list of cell names of the bypass capacitors provided in the power supply (not shown)
Is displayed on the display 18 of the CAD (step S1 in FIG. 5).
).

One cell name (No.i) from this cell name list
Is selected (step S2 in FIG. 5), a flag (not shown) of the selected cell name (No. i) is turned on (FIG. 5).
Step S3).

In the state where the cell name list is displayed,
When the drawing button (not shown) is pressed (step S4 in FIG. 5), it is determined whether or not the bypass capacitors of all the selected cell names satisfy predetermined conditions (step S5 in FIG. 5). It is checked whether or not the wiring is connected to the wiring path between VCC and the ground cell GND (step S6 in FIG. 5), and if the connection is correct (step S7 in FIG. 5), the wiring length (L1) of the wiring path, the wiring width (W), the center coordinates (x.y), the signal name (Ci), etc. are extracted (step S8 in FIG. 5), and it is confirmed that there is no wiring rule violation according to a predetermined wiring rule (step S9 in FIG. 5).
The signal name table (not shown) of the bypass capacitor is updated according to the bypass capacitor information (step S10 in FIG. 5), and the elliptical data indicating the effective range is calculated to update the bypass capacitor effective range information table (TB) (FIG. 5). FIG. 5 step S10).

As described above, the power supply table (TA) as shown in FIG. 2 and the bypass capacitor effective range information table (T) for all the bypass capacitors of the respective power supplies.
After B) is created, the type (signal name) of the power source for displaying the effective range of the bypass capacitor is selected on the bypass capacitor display setting panel shown in FIG. The effective range of the bypass capacitor is displayed only within the power supply area as shown in FIGS. 4 and 10A.

The processing operation by the bypass capacitor effective range display processing routine (PB) at this time will be described with reference to FIG. Here, first, the type (signal name) of the power source for displaying the effective range of the bypass capacitor is selected on the bypass capacitor display setting panel shown in FIG. 3 (steps S21 and S22 in FIG. 6), and the selected type is selected. The power supply flag (No. j) is turned on (step S23 in FIG. 6).

Further, after that, when the drawing button (for example, all display) is pressed on the bypass capacitor display setting panel (step S24 in FIG. 6), the signal names of the selected power supply are set for all the bypass capacitors. , Drawing data of an ellipse indicating the effective range of each bypass capacitor is generated, and a portion of the drawing data of the ellipse that protrudes from the power supply area of the power supply is cut and output. (Steps S25 to S29 in FIG. 6). Here, when the effective range of the target bypass capacitor is drawn as an ellipse on the screen, it is displayed by taking an AND with the power supply area. As a result, as shown in FIG. 10A, the effective range of the portion beyond the power supply area (extruded) is not drawn, and even if a plurality of power supplies are displayed at the same time, the power supply with two or more ellipses is displayed. The effective range of the bypass capacitor for each power supply can be easily and accurately grasped, and places where the bypass capacitor is ineffective or excessively placed on the board It is possible to easily and accurately grasp the location where the error occurs. At this time, concentric ellipses with different effective ranges are represented by colors,
Alternatively, more accurate evaluation can be performed by outputting a display based on a change in density or the like.

[0070]

As described above in detail, according to the present invention, it is possible to visually grasp the performance evaluation related to the location of the bypass capacitor for each power supply at the time of designing the printed circuit board layout. The location of the capacitor can be determined efficiently.

The effective range of the bypass capacitor on the printed circuit board of each power supply handled by the board is displayed in the power supply area for each type of power supply, so that the effective range of the bypass capacitor for each power supply is clearly defined. In addition, it can be easily recognized, and the location can be determined efficiently.

Further, the effective range of the bypass capacitor is displayed by a circle for each power supply present on the board, and the circle is displayed only inside the target power supply area, so that a plurality of power supplies are present on one board. Even in such a case, it is possible to provide an environment in which the effective range of the bypass capacitor for each power supply area can always be correctly and easily grasped.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing main system components according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the entire operation in the embodiment of the present invention.

FIG. 3 is a diagram showing a configuration example of a bypass capacitor display setting panel in the embodiment.

FIG. 4 is a view showing an algorithm for displaying an effective range of a bypass capacitor for each power supply in the embodiment.

FIG. 5 is a flowchart showing an effective range calculation processing routine (PA) of a bypass capacitor for each power supply in the embodiment.

FIG. 6 is a flowchart showing a bypass capacitor effective range display processing routine (PB) in the embodiment.

FIG. 7 is an operation principle diagram for explaining a processing operation when the effective range of the bypass capacitor is drawn as an approximate ellipse in the embodiment.

FIG. 8 is an operation principle diagram for explaining a processing operation when the effective range of the bypass capacitor is drawn as an approximate ellipse in the embodiment.

FIG. 9 is an operation principle diagram for explaining a processing operation when the effective range of the bypass capacitor is drawn as an approximate ellipse in the embodiment.

FIG. 10 is a diagram illustrating a case where an effective area of a bypass capacitor is drawn as an ellipse. FIG. 9 is a diagram illustrating a case where the drawing is performed by contrasting a case where the drawing is performed without performing the cutting process.

[Explanation of symbols]

11: PCB layout CAD processing unit, 12: bypass capacitor placement evaluation tool, 13: operation input unit, 14: parameter input unit, 15: storage unit, 16: display control unit, 17: wiring rule violating capacitor list display control unit, 18: CAD display section, 18A, 18B: Effective range display screen of bypass capacitor, TA: Power supply table, TB: Effective range information table of bypass capacitor, PA: Effective range calculation processing routine of bypass capacitor for each power supply, PB: Bypass Processing routine for displaying the effective range of capacitors.

Claims (10)

[Claims] 1. A printed circuit board design support system having a function of evaluating an arrangement state of a bypass capacitor interposed in a power supply circuit of a printed circuit board, the input system including layout information of a printed circuit board, structure and material information of the printed circuit board. Means for calculating the effective range of the bypass capacitor based on the information; means for selectively displaying a list of signal name information indicating the type of each power supply handled on the printed circuit board; and printing of the power supply according to the selected signal name information Means for displaying the effective range of the bypass capacitor on the printed circuit board, wherein the effective range of the bypass capacitor on the printed circuit board is displayed for each type of power supply handled by the printed circuit board. Support system. 2. A printed circuit board design support system having a function of evaluating an arrangement state of a bypass capacitor interposed in a power supply circuit of a printed circuit board, the input including a printed circuit board layout information, a printed circuit board structure and material information. Means for calculating the effective range of the bypass capacitor based on the information; means for selectively displaying a list of signal name information indicating the type of each power supply handled on the printed circuit board; and printing of the power supply according to the selected signal name information Means for displaying the effective range of the bypass capacitor on the printed circuit board only within the area of the power supply. The effective range of the bypass capacitor on the printed circuit board of each power supply handled by the printed circuit board is classified by the type of the power supply. A printed circuit board design support system characterized in that the information is displayed in the power supply area every time. 3. The printed circuit board design support system according to claim 1, wherein the input information includes impedance information indicating an effective range designated by a user. 4. A printed circuit board design support system for designing a printed circuit board layout, comprising: a board layout information storage unit storing board layout information necessary for the printed circuit board layout design; Means for determining a parameter relating to a wiring path of a bypass capacitor for noise removal arranged on the printed circuit board, and determining an effective range of the bypass capacitor from impedance characteristics calculated based on the parameter; A printed circuit board design support system, comprising: display means for displaying the range only within the target power supply area and displaying the range on a display screen so that the range can be visually confirmed. 5. An apparatus according to claim 1, further comprising calculating means for calculating an effective range of the bypass capacitor as an approximate ellipse, wherein the approximate ellipse calculated by the calculating means is visually displayed in a corresponding power supply area. Claim 1 or 2 or 3
Or a printed circuit board design support system according to 4. 6. The display device according to claim 1, wherein the effective range of the bypass capacitor on the printed circuit board of each power supply handled by the circuit board is visually displayed by a display color different for each impedance. 5. The printed circuit board design support system according to 5. 7. The effective range of a bypass capacitor on a printed circuit board of each power supply handled by the board is visually displayed in a display color different for each type of power supply. A printed circuit board design support system according to 4 or 5. 8. A bypass capacitor on a printed circuit board based on input information including printed circuit board layout information, printed circuit board structure and material information, and impedance information indicating an effective range specified by a user. Procedure for calculating the effective range of the power supply, Procedure for displaying a list of signal name information indicating the type of each power supply handled by the printed circuit board in a selectable manner, Effectiveness of the bypass capacitor on the printed circuit board of the power supply according to the selected signal name information A program for executing the procedure for generating the display data for displaying the range is recorded. In the printed circuit board design CAD system, the effective range of the bypass capacitor on the printed circuit board for each power supply type handled by the board. A machine-readable recording medium characterized by being able to display an image. 9. A bypass capacitor on a printed circuit board based on input information having printed circuit board layout information, printed circuit board structure and material information, and impedance information indicating an effective range specified by a user. Procedure for calculating the effective range of the power supply, Procedure for displaying a list of signal name information indicating the type of each power supply handled by the printed circuit board in a selectable manner, Effectiveness of the bypass capacitor on the printed circuit board of the power supply according to the selected signal name information Record the program to execute the procedure to generate the display data to display the range only in the area of the power supply, and record the effective range of the bypass capacitor on the printed circuit board of each power supply handled by the board Machine readable, characterized by displaying within the power supply area for each power supply type Recording media. 10. A program for executing a procedure for calculating an effective range of a bypass capacitor as an approximate ellipse, wherein the approximate ellipse calculated by the procedure is visually displayed in a corresponding power supply area. 9. The machine-readable recording medium according to claim 7, wherein: