JP3078939B2 - Circuit division design control apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for designing a circuit division design, and more particularly to a method and apparatus for controlling a design performed by dividing a circuit into a plurality of blocks.

[0002]

2. Description of the Related Art In recent years, CAD for printed circuit board design
With the widespread use of (Computer Aided Design), automatic placement methods and devices that automatically determine the positions of electronic components when designing printed circuit boards are being adopted. In general, in such an automatic placement method and automatic placement device, placement on a printed circuit board is emphasized with emphasis on the size of components in terms of housing the circuit itself, and on the connection relationship between components in terms of the original function of the circuit. Determine the position. In other words, components which are important and relatively large in functioning, such as ICs and QFPs (both are a kind of integrated circuits), are connected to components near the cores. However, in such a case, discrete components such as other resistors and capacitors are concentrated around the core component, so that not only wiring space cannot be secured, but also the flow of circuit signals on the printed circuit board is reduced. Not eligible for placement,
Even if all parts are placed on the printed circuit board, they will not be placed properly, so that CAD
It is often necessary to make manual corrections by using the interactive processing function of.

[0003] In order to realize such an automatic arrangement that does not require such correction, the circuit is divided into a plurality of blocks in order to prevent the components from being densely packed, and the connection relationship between the components in each of the divided blocks. A method has been conceived in which an arrangement position is determined on the basis of the above, and then the arrangement is performed on a printed board.

[0004]

However, even in the conventionally known MIN-CUT method or the like that performs division so that the number of nets connecting blocks is minimized, the division up to the division according to the signal flow is still not suitable. Not done. Therefore, there is still a problem in terms of the efficiency of the signal flow in the entire circuit.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a circuit division design control method and apparatus for performing the best circuit division by giving weights to each net according to importance. It is.

[0006]

According to a first aspect of the present invention, there is provided an apparatus for designing an electric or electronic circuit by dividing the circuit into a plurality of blocks. A component number-based weighting unit that weights the net according to the number of components to be connected based on the connection information stored in the storage unit; and a circuit dividing unit that divides the circuit into a plurality of combinations of blocks. And a weight calculator for calculating the sum of the weights of the respective nets connecting the respective blocks for each of the divisions made by the circuit divider, and selecting a circuit division having the best calculation result of the weight calculator. so,
And a control unit for controlling the design apparatus so as to perform the layout design for each block based on the division.

According to a second aspect of the present invention, there is provided a method for designing an electric or electronic circuit by dividing the circuit into a plurality of blocks.
A storage step of storing predetermined circuit information; a component number-based weighting step of weighting a net in accordance with the number of components to be connected based on the connection information obtained as a result of the storage step; A circuit dividing step of dividing into several ways, a weight calculating step of calculating a sum of weights of respective nets connecting the respective blocks for each of the divisions as a result of the circuit dividing step, and a calculation result of the weight calculating step. A control step of selecting the best circuit division and controlling the design so as to perform the layout design for each block based on this division.

According to the third aspect of the present invention, instead of the number-of-parts-based weighting unit, a net is weighted according to the length written in the circuit diagram based on the circuit diagram stored in the storage unit. 2. A circuit division design control device according to claim 1, further comprising a net length-based weighting section for giving. In the invention according to claim 4, instead of the number-of-parts-based weighting step, based on a circuit diagram stored as a result of the storing step, a net that weights the net according to the length written in the circuit diagram 3. The method according to claim 2, further comprising a length-based weighting step.

According to a fifth aspect of the present invention, in place of the component-number-based weighting unit, a net is connected in accordance with an attribute between pins connected to the net based on attribute information between pins stored in the storage unit. 2. The circuit division design control device according to claim 1, further comprising a pin attribute-based weighting section for giving a weight representing the importance of the net to the net. According to the invention of claim 6, in place of the component-number-based weighting step, based on attribute information between pins stored as a result of the storage step, a net is connected in accordance with an attribute between pins connected to the net. 3. A circuit division design control method according to claim 2, further comprising a pin attribute-based weighting step of giving a weight indicating importance to the net.

In the invention according to claim 7, in place of the component number-based weighting unit, based on the frequency of the signal flowing through the net stored in the storage unit, the frequency of the signal flowing through the net is changed. The circuit division design control device according to claim 1, further comprising a frequency-based weighting unit that gives a weight representing the importance to the net.

According to an eighth aspect of the present invention, in place of the component-number-based weighting step, a frequency for giving a weight indicating the importance of the net to the net according to the frequency of a signal flowing through the net stored as a result of the storing step. The method according to claim 2, further comprising a base-type weighting step.

[0012]

With the above configuration, in the circuit division design control device according to the first aspect of the present invention, the storage section stores predetermined circuit information. A circuit divider divides the circuit into several combinations of blocks. The component number-based weighting unit assigns a weight indicating the importance of each net to each net based on the number of components connected to the net based on the connection information stored in the storage unit. The weight calculation unit calculates the sum of the weights of the nets connecting the divided blocks for each division. After the control unit selects the circuit division having the best sum of the weights, the control unit controls the design apparatus to perform the layout design based on the division.

[0013] In the circuit division design control device according to the third aspect of the present invention, the net length-based weighting section gives a weight to each net according to the length of each net on the circuit diagram. In the circuit division design control device according to the invention of claim 5,
A pin attribute-based weighting unit assigns a weight to each net according to an attribute between pins connected to each net. In the circuit division design control device according to the seventh aspect of the present invention, the frequency-based weighting unit assigns a weight to each net according to the frequency of a signal flowing through each net.

The second, fourth, sixth, and eighth inventions respectively depict the first, third, fifth, and seventh inventions, which are device inventions, as method inventions. Terms 1, 3,
The same operations as those of the fifth and seventh inventions are performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A circuit division design control apparatus and method according to the present invention will be described below based on embodiments. (First Embodiment) FIG. 1 is a block diagram of an embodiment of a circuit division design control apparatus according to the first and second aspects of the present invention.
In this figure, reference numeral 101 denotes a storage unit, which stores predetermined circuit information as shown in FIG. 11, such as the approximate position, type and number of parts, connection information between the parts, the frequency of symbols flowing through the net, and the connection of the net. Parts are classified by parts (FIG. 11A).
It is stored for each circuit (FIG. 11B). Further, the outer shape of the substrate is also stored (FIG. 11C). In terms of hardware, it is shared with a circuit-division-type design apparatus main body 100 in which the circuit-division design control apparatus is integrally incorporated. Note that the basic configuration of the design apparatus main body 100 is the same as that according to the related art. Reference numeral 102 denotes a circuit division unit, which performs some circuit division while referring to information stored in the storage unit 101. Reference numeral 103 denotes a number-of-parts-based weighting unit which checks the number of parts connected to each net while referring to information in the storage unit 101, and assigns a small weight to a net having a large number of parts and a large weight to a net having a small number of parts. give. Here, a net is a connection path that electrically connects parts and, as a result, a boundary that is separated or surrounded by parts (not necessarily an electric wire, Conductive material foil or the like printed on the substrate). Reference numeral 104 denotes a weight calculation unit, which calculates the total sum of weights assigned to each net by the component number-based weighting unit 103 for each division performed by the circuit division unit 102.

The weighting method of the component number-based weighting unit is as follows. The number of components connected to each net is checked.
The maximum number is obtained, and then the weight of the net having the maximum number of parts is 1
The weight of each net is determined so that The reason is that a signal transmitted is weaker in a net having a larger number of branches, and therefore, it is considered that a smaller sum of weights is preferable in terms of detecting a weaker signal. In this case, although some divisions are adopted in this case, space information for a circuit composed of an IC or a capacitor for a personal computer or a word processor to be easily arranged in a predetermined board, and an original electronic circuit cannot be used. In order to perform the functions without any problem, a block is roughly formed for each rough function, and a technique of a certain amount of division as accumulated know-how in design technology is referred to. Next, some of the general know-how of division will be exemplified, and the reason will be described. The dividing lines emphasize the X (left and right) and Y (up and down) directions.

This is because the operation panels such as word processors are usually arranged in the X and Y directions, the CRT display is based on the X and Y directions, and it is convenient not only in design but also in manufacturing. It depends. For this reason, the division obliquely in both directions is avoided as much as possible. Also, the presence of a block penetrating the front and back of the substrate can be avoided as much as possible. With emphasis on the block division of an IC (including QFP), it is important to attach the attached parts of the IC to the same divided block as the IC to which it is attached.

This is because the IC is important for the functioning of the circuit, and the resistance, capacitance and coil are only accessories.
This is because it is not preferable to be arranged apart from C, and because the shape is small, it can be arranged at any time. Input / output of power supply, output signal and upstream of IC on circuit,
Align downstream position. Each block should be approximately the same size. This is for equalizing the design load in each block. However, this does not apply to a block including a part that clearly makes an exception. Each block should have almost the same number of ICs. For the same reason. For similar products such as Chinese word processors and Japanese word processors, basic circuits and circuits with some improvements or additional functions, refer to similar or basic circuits. Depending on the application and size of the circuit, the designer may be able to determine the approximate block shape, number of blocks, or ICs per block.
Enter the number of For the most important circuits in each device such as a dictionary in a word processor, a color tone adjustment in a color television, and the like, a designer separately instructs the layout. And so on.

For this reason, as shown in FIG. 11, not only the general arrangement of each component on the substrate, but also other circuit diagram-like information and space information, or a piping system diagram in a machine factory or a chemical plant. Also, a drawing corresponding to a device schematic layout diagram, and the like are stored in the storage unit as needed. In addition, know-how about unique division is used according to the use of the circuit, the use of the device to which the circuit is attached, and the like, and it is needless to say that necessary information is stored. However, the know-how of division and the details of the stored contents are not the gist of the present invention, and therefore, detailed descriptions thereof are omitted.

FIG. 2 shows the number-of-parts-based weighting section 1.
2 specifically shows a state of weighting. In the figure, reference numerals 201 to 203 denote parts 204 to 21
This is a net representing the connection state between the four. The number-of-parts-based weighting unit first checks the number of connected parts for all nets and finds the maximum number. In the example of FIG. 2, the maximum number is 6. Next, a value obtained by dividing the maximum number by the number of components connected to each net is set as the weight of each net. That is,
The weight of the net will be inversely proportional to the number of parts. FIG.
In the example, the weights of the nets 201, 202, and 203 are 1, 2, and 3, respectively.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. The type and number of circuit components, the connection relationship, and the like are input to the storage unit 101 as predetermined circuit information (a1). The circuit dividing unit 102 divides the circuit into a plurality of blocks (a2). As described above, this division is performed in several ways. The component number-based weighting unit weights each net based on the number of components connected to each net for each of the divisions (a3). The weight calculator calculates the sum of the net weights for each division (a
4). The control unit selects the division that minimizes the sum of the weights (a5). Then, the control unit controls the design device main unit to perform circuit layout design for each block based on the selected division (a6).

Next, FIG. 4 shows an example in which division is actually performed by the circuit division design control apparatus in comparison with a case in which the circuit is designed by the prior art. FIG. 4A shows a specific example of the division result by the circuit division design control device according to the related art, and FIG. 4B shows the result of the division by the circuit division design control device of the present invention. One specific example is shown. FIG.
In (b), the signal flow from left to right is clearly satisfactorily captured, and components to be arranged nearby form a block. (Second Embodiment) A circuit division design control apparatus and method according to the third and fourth aspects of the present invention will be described based on an embodiment.

The basic configuration and basic operation flow of this embodiment are not different from those of the first embodiment. However, in the basic configuration shown in FIG. 1, the predetermined circuit information stored in the storage unit 101 is a circuit diagram in which an approximate position of each component is described.
The difference is that the net is weighted not by the number-of-parts weighting unit 103 but by the net length-based weighting unit that weights the net according to the length of the net written on the circuit diagram. Therefore, in the flowchart shown in FIG. 3, the weighting of the nets between blocks in step (a3) is different depending on the length of the nets. Here, attention is paid to the length of the net as the weighting of the net because the components that are related to each other, such as an IC and a resistor for the IC, are arranged closer to each other. To avoid as much as possible the intrusion of electromagnetic noise from the Internet, as a matter of course, they must be placed close to each other because of their priority for placement, and conversely, longer nets generally have lower importance Is considered.
In this case, the method of calculating the net length is shown in FIG.
As conceptually shown in FIG. 1, since the components connected to the net and the approximate position are stored for each net, it can be easily obtained. That is, the position coordinates are (x ₁ ,
In this embodiment, the length l _{12 of the} net connecting the two components y ₁ , z ₁ ) (x ₂ , y ₂ , z ₂ ) is IC or Q in this embodiment.
L ₁₂ = ｛(x ₁ −x ₂ ) ² + (y ₁ −y ₂ ) ² + (z ₁ )
−z) ² ｝ ^1/2 and connecting IC or QFP to each other is as follows: l ₁₂ = 1.3 ｛(x ₁ -x ₂ ) ² + (y ₁ -y ₂ ) ² +
(Z ₁ −z) ² ｝ ^1/2 . Here, in this case, the reason why the numerical value of 1.3 is multiplied is that the IC and QFP are often arranged with a large number of accessory parts around them.

The length l of the net connecting the three parts
₁₂₃ is set to l ₁₂₃ = l ₁₂ + l ₂₃ . In the arrangement on the same substrate, z ₁ and z ₂ are both 0. In addition to the above, if the number of components connected to the net increases, the relationship between input and output of the signals is also considered, but these are not the gist of the present invention and are not important at the weighting stage. Therefore, further description is omitted.

Next, the operation of the net length-based weighting section will be described in some detail. Referring to the information in the storage unit, the length of each net on the circuit diagram is checked, and a small weight is given to a net having a long net length on the circuit diagram, and a large weight is given to a net having a short net length on the circuit diagram. More specifically, the net length of each net on the circuit diagram is examined, the maximum net length is obtained, and then the weight of each net is determined so that the weight of the net having the maximum net length becomes 1.

FIG. 5 specifically shows the manner of weighting in the net length-based weighting section of this embodiment. In this drawing, 501, 502, and 503 are parts 5
This is a net representing the connection state between the devices 04, 505, and 506. The net length-based weighting means retrieves the length of each net on the circuit diagram from the storage unit, finds the maximum net length, and multiplies the inverse of the net length by a constant so that the weight of the net with the maximum net length becomes 1. Is the weight of each net. That is, the weight of the net is inversely proportional to the net length. In the example of FIG. 5, the nets 501, 502, 503
Are 8, 4, 2, the maximum net length is 8, the constant is 8, and the weights are 1, 2, and 4, respectively.

FIG. 6 shows a specific example of the result of division performed by the circuit division design control device. FIG.
Here, a circuit for the same circuit as that used in FIG. 4A, the result clearly shows that the signal flow from left to right is satisfactorily captured, and the components to be arranged nearby form a block. (Third Embodiment) A circuit division design control device according to the fifth and sixth aspects of the present invention will be described based on an embodiment.

In this embodiment, the basic configuration and the basic operation flow are not different from those of the first and second embodiments. However,
In the configuration diagram shown in FIG. 1, the storage unit 101 stores, as predetermined circuit information, the attribute of a pin connected to each net, and replaces the component number-based weighting unit 103 with a pin attribute-based weighting unit. Is different. Therefore, in the operation flow diagram shown in FIG.
The difference is that the weighting of the nets between blocks in 3) is based not on the number of components connected to the nets but on the attributes of the pins.
Here, we focus on the attributes of the pins because the electrical signal flows from the output pin of each component to the input pin on the net,
An object of the present invention is to minimize the division between output pins and input pins so that the signal flow between blocks is smooth.

The operation of the pin attribute-based weighting unit is as follows. The information of the storage unit is referred to, the attribute of the pin connected to each net is checked, and the input-input or output-output attribute is determined. A small weight is given to the connecting net, and a large weight is given to the net connecting the pins having the output-input attribute. Note that the term “pin” here is more precisely a concept of “an input / output signal extraction section” of each component, and is not limited to a pin made of a thin metal wire.

FIG. 7 shows a specific example of weighting in the pin attribute-based weighting section. In this figure, 7
Reference numeral 01 denotes a net that connects the components 702, 703, 704, and 705. “In” and “out” written in each component indicate whether the pin connected to the net is an input pin or an output pin. In this example, the attribute of the pin connected to the net is 1 when the attribute is input-input or output-output, and 3 when the attribute is output-input. Therefore, in the example of FIG.
Weight 1 and part 7 between 703 and parts 704-705
02-704, part 702-705, part 703
Weight 704 is given between 704 and parts 703-705.

FIG. 8 shows a specific example of the result of the division performed by the circuit division design control apparatus, and shows the same circuit as that used in FIG. 4 (a). Fig. 4
Compared to (a), the result clearly shows that the signal flow from left to right is well captured, and the components to be arranged close to each other form a block. Fourth Embodiment A circuit division design control apparatus and method according to the seventh and eighth aspects of the present invention will be described based on an embodiment. Also in this embodiment, the basic configuration and the basic operation flow are as follows:
This is the same as the previous three embodiments. However, the first shown in FIG.
When compared with the configuration diagram of the embodiment, the predetermined circuit information stored in the storage unit 101 includes a frequency of a signal flowing through each net, and a frequency-based weighting unit is used instead of the component-number-based weighting unit 103. This is different in that weighting is performed according to the frequency of a signal flowing through each net. Therefore, the content of step (a3) is different also in the flowchart shown in FIG. Here, we focused on the frequency because the higher the frequency of the signal, the harder it flows through the net,
This is because the net length needs to be shortened, and thus it is highly necessary to make the same block.

The frequency-based weighting section refers to the information in the storage section to check the frequency of the signal flowing through each net, and assigns a small weight to the low-frequency signal and the net to which the DC signal flows, and the net to which the high-frequency signal flows. Is given a large weight. FIG. 9 shows a specific example of weighting in the frequency-based weighting unit. In the figure, 901,
Reference numerals 902 and 903 are nets indicating the connection state between the components 904 to 914. In this figure, the signal flowing through each net is 1
Less than 1 MHz, less than 10 MHz, 10 MHz
More than 50MHz, divided into four stages of 50MHz or more,
Weights of 1 to 4 are given to each. Therefore,
Weights of 1, 3, and 4 are given to the net 901 through which the 60-Hz signal flows, the net 902 through which the 10-MHz signal flows, and the net 903 through which the 60-MHz signal flows.

FIG. 10 is a specific example of the result of division performed by the circuit division design controller, and FIG.
The figure shows a circuit for the same circuit as that used in FIG.
4A, the result clearly shows that the signal flow from left to right is satisfactorily captured, and the components to be arranged nearby form a block.

Although the present invention has been described based on the embodiments, it goes without saying that the present invention is not limited to the above embodiments. That is, for example, in the first and second aspects of the invention, the number of parts is 1 to 5
, 6-10, etc., and weighting may be given to each net belonging to each stage. According to the third and fourth aspects of the present invention,
It may be divided into several stages such as 3 cm and 3 to 6 cm, and a weight may be given to each net belonging to each stage. In the fifth and sixth aspects of the present invention, any value may be used as the weight value as long as the magnitude relationship is maintained without using 1 and 3. In the inventions of claims 7 and 8, the steps may be divided more finely, more roughly, or weighted in proportion to the frequency flowing through the net. The invention described in each claim is appropriately combined. The weighting method may be such that the result having the maximum value instead of the result having the minimum value is the best. In the main part of the design device, not only the same block but also the nets of other blocks, etc., besides the net etc. of the same block, so that the net etc. where a weak signal current flows is not placed near the net where a relatively large current flows. Other functions, such as paying attention, may also be added to check points to be individually noted.

[0035]

According to the first and second aspects of the present invention,
By paying attention to the fact that a signal is weak in a net having a large number of signal branches, not only can the circuit be divided along the signal flow, but also components that should be placed close to each other can be prevented from gathering in the same block. Therefore, almost no manual correction work is required.

According to the third and fourth aspects of the present invention, it is noted that a net having a long net length has a low importance on a circuit diagram. The same circuit division can be performed. According to the fifth and sixth aspects of the present invention, the connection between the output pin and the input pin is divided by noting that the electric signal flows from the output pin to the input pin of each component on the net. It is possible to perform the circuit division which is suppressed as much as possible and which can be reasonably adjusted to the flow of the signal from the output pin to the input pin, and thus requires almost no manual correction work.

According to the seventh and eighth aspects of the present invention, a high-frequency signal is unlikely to flow on a net, and is likely to generate noise when flowing on the net. Therefore, it is necessary to reduce the net length as the high-frequency signal flows. By paying attention to this fact, it is possible to perform circuit division without cutting the path of the high-frequency signal, and thus, the high-frequency characteristics are good,
In particular, automatic layout design with less noise can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a circuit division design control device according to the first and second aspects of the present invention.

FIG. 2 is a diagram specifically showing a manner of weighting by a component number-based weighting unit in the embodiment.

FIG. 3 is an operation flowchart of the embodiment.

FIG. 4A is a diagram specifically showing a result of circuit division by a circuit division design control device according to the related art. FIG. 4B is a diagram specifically showing a result of circuit division according to the embodiment.

FIG. 5 is a diagram specifically showing a state of weighting by a net length-based weighting unit in the circuit division design control device according to the third and fourth aspects of the present invention.

FIG. 6 is a diagram specifically showing a result of circuit division in the circuit division design control device according to the third and fourth aspects of the present invention.

FIG. 7 is a diagram specifically showing a state of weighting by a pin attribute-based weighting unit of the circuit division design control device according to the fifth and sixth aspects of the present invention.

FIG. 8 is a diagram specifically showing a result of circuit division in the circuit division design control device according to the fifth and sixth aspects of the present invention.

FIG. 9 is a diagram specifically showing a state of weighting by a frequency-based weighting unit of the circuit division design control device according to the invention of claims 7 and 8;

FIG. 10 is a diagram specifically showing a result of circuit division in the circuit division design control device according to the seventh and eighth aspects of the present invention.

FIG. 11 is a conceptual diagram of storage contents of a storage unit in each embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 circuit division design apparatus main body 101 storage section 102 circuit division section 103 number-of-parts-based weighting section 104 weight calculation section 105 control section

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-59669 (JP, A) JP-A-63-226775 (JP, A) JP-A-3-149664 (JP, A) JP-A-4- 349579 (JP, A) JP-A-5-6410 (JP, A) JP-A-5-73643 (JP, A) JP-A-5-82649 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 17/50

Claims (8)

(57) [Claims] 1. An apparatus for designing an electric or electronic circuit by dividing it into a plurality of blocks, comprising: a storage unit for storing predetermined circuit information; and a number of components to be connected based on connection information stored in the storage unit. A number-of-parts-based weighting unit that weights the net accordingly; a circuit division unit that divides the circuit into several combinations of a plurality of blocks; and a connection between the blocks for each division made by the circuit division unit. A weight calculation unit that calculates the sum of the weights of the respective nets, and a design apparatus that selects a circuit partition in which the calculation result of the weight calculation unit is the best, and performs the layout design for each block based on the division. And a control unit for controlling the circuit division design control device. 2. A method for designing an electric or electronic circuit by dividing the circuit into a plurality of blocks, comprising: a storage step of storing predetermined circuit information; and a number of components to be connected based on connection information as a result of the storage step. A number-of-parts-based weighting step for weighting the net accordingly; a circuit division step of dividing the circuit into a plurality of combinations of blocks; and connecting the blocks for each division resulting from the circuit division step. A weight calculation step for calculating the sum of the weights of the respective nets; and selecting a circuit partition in which the calculation result of the weight calculation step is the best, and controlling the design so as to perform the placement design for each block based on the partition. A circuit dividing design control method, comprising: 3. A net length-based weighting method for weighting a net according to a length written in a circuit diagram based on a circuit diagram stored in the storage unit, instead of the component number-based weighting unit. The circuit division design control device according to claim 1, further comprising a unit. 4. A net length-based type that weights a net according to a length written on a circuit diagram based on a circuit diagram stored as a result of the storing step, instead of the component number-based weighting step. 3. The method according to claim 2, further comprising a weighting step. 5. A method according to claim 1, wherein said weighting unit is based on attribute information between pins stored in said storage unit.
2. The circuit division design control device according to claim 1, further comprising a pin attribute-based weighting unit that gives the net a weight indicating the importance of the net in accordance with an attribute between pins connected to the net. 6. The importance of a net is represented in accordance with the attribute between pins to which the net is connected, based on the attribute information between pins stored as a result of the storage step, instead of the component number-based weighting step. 3. The circuit division design control method according to claim 2, further comprising a pin attribute-based weighting step of giving a weight to the net. 7. A weight representing the importance of a net according to the frequency of a signal flowing through a net, based on the frequency of a signal flowing through the net stored in the storage unit, instead of the component count based weighting unit. 2. The circuit division design control device according to claim 1, further comprising a frequency-based weighting unit for giving the net. 8. A weight representing the importance of a net according to the frequency of a signal flowing through a net, based on the frequency of a signal flowing through the net stored as a result of the storing step, instead of the number-of-parts-based weighting step. 3. The circuit division design control method according to claim 2, further comprising a frequency-based weighting step of giving the value to the net.