JP3065285B2 - Automatic placement and routing apparatus and automatic placement and routing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an automatic placement and routing apparatus and an automatic placement and routing method for designing a wiring of an integrated circuit or the like.

[0002]

2. Description of the Related Art In an integrated circuit or the like, since the wiring width and the wiring interval are narrow, the amount of crosstalk received by a certain wiring from an adjacent wiring exceeds an allowable value, causing a problem that a circuit malfunction occurs due to crosstalk noise. ing. An example of a conventional automatic placement and routing apparatus for solving this problem is described in Japanese Patent Laid-Open Publication No. Hei 3-3347. The automatic placement and routing apparatus described in this publication includes a parallel wiring length calculation unit that calculates a parallel wiring length for each wiring, a crosstalk amount calculation unit that calculates a crosstalk amount given to wiring for each wiring, and a new wiring path. A crosstalk amount determining unit that determines whether the crosstalk amount exceeds an allowable value each time a search is performed, and a wiring route that is related to the wiring when there is a wiring that exceeds the allowable value in the crosstalk amount determination. , A line length limiter is temporarily generated in an adjacent wiring grid, and a new wiring path is searched for in consideration of the generated line length limiter.

In the above-described conventional method, in the wiring processing, when a new wiring path is searched, the parallel wiring length between the searched wiring path and the existing wiring path adjacent thereto is calculated for each wiring, and the calculated parallel wiring length is calculated. Based on the length, the amount of crosstalk given to the wiring on the existing wiring route by the newly searched wiring of the wiring route is calculated, and it is determined whether or not the calculated crosstalk amount exceeds an allowable value. If there is a wiring that exists, a wire length limiter is generated in the wiring grid adjacent to the wiring route related to the wire, and a new wiring route is searched in consideration of the generated wire length limiter. Crosstalk can be reduced to an allowable value.

In the wiring process, the wiring length of the wiring is estimated from the arrangement information, and when the wiring length exceeds a certain range, the wiring distance between the wiring and another wiring is changed to the normal wiring distance. There is a method of increasing the crosstalk and reducing the amount of crosstalk received from the adjacent wiring.

[0005] However, in recent years, the miniaturization of integrated circuits has been rapidly progressing, and as a result, wiring widths and wiring intervals have become increasingly narrower, and not only influences from adjacent wirings but also influences from other adjacent wirings. To receive.

The manner in which a certain wiring is affected by crosstalk from other adjacent wirings will be described with reference to FIG. FIG.
In the figure, wiring is performed in units of wiring grids 506 and 507 arranged in the vertical and horizontal directions.

Here, when attention is paid to the amount of crosstalk with respect to the wiring 501, if the distance between the wirings becomes narrow, the wiring 5
In addition to the wiring provided on the wiring grid adjacent to 01,
The influence from the wiring 502 two grids ahead and the influence from the wiring 503 wired to the wiring grid further ahead must also be considered. Further, when the substrate is composed of a plurality of layers, it is necessary to consider the influence of wiring that crosses in different layers. In some cases, the talk amount cannot be reduced below the allowable value.

Also, in a method of unconditionally increasing the wiring interval between adjacent wirings for a wiring whose wiring length exceeds a certain range, an adjacent wiring can be formed without actually increasing the wiring interval between adjacent wirings. Is short, even if the crosstalk amount does not exceed the allowable value, the wiring interval between adjacent wirings is increased, and the wiring ratio is reduced.

[0009]

The above-mentioned conventional automatic placement and routing apparatus has the following problems. (1) In an automatic placement and routing apparatus that considers only the influence of the wiring provided on the adjacent wiring grid, crosstalk is worsened by the influence of wiring that is not adjacent. (2) If the wiring length of the wiring exceeds a certain range, and the wiring distance between adjacent wirings is unconditionally increased, the wiring distance between adjacent wirings is unnecessarily increased, and the wiring rate decreases. Would.

An object of the present invention is to reduce the wiring ratio without reducing
An object of the present invention is to provide an automatic placement and routing apparatus and method capable of reducing crosstalk in consideration of the influence of non-adjacent wiring.

[0011]

According to the present invention, in order to achieve the above object, a crosstalk amount calculating means for calculating a crosstalk amount received by a certain wiring from another wiring, and the crosstalk amount calculating means calculating the crosstalk amount. A crosstalk amount determining unit that determines whether the crosstalk amount exceeds a predetermined allowable value; and a crosstalk amount that includes the calculated crosstalk amount when the calculated crosstalk amount exceeds the allowable value. Buffer insertion means for dividing the wiring path and inserting a buffer in the middle.

According to an embodiment of the present invention, the crosstalk amount calculating means calculates a crosstalk amount by calculating a parasitic capacitance value between the certain wiring and the other wiring.

According to another embodiment of the present invention, the crosstalk amount calculating means may be configured such that the certain wiring is parallel or intersected with the certain wiring in a same layer and a certain wiring adjacent to the certain wiring. The amount of crosstalk received from the wiring to be calculated is calculated.

According to the present invention, the crosstalk amount calculating section
The amount of crosstalk received from adjacent wirings in the same layer and parallel or crossing wirings in different layers is calculated for each wiring, and the crosstalk amount determination unit determines that the calculated crosstalk amount exceeds an allowable value. Then, the wiring route of the wiring is divided and a buffer is inserted in the middle,
This is to reduce the wiring length.

Therefore, the amount of crosstalk between each wiring and another wiring can be reduced to an allowable value or less.

In order to achieve the above object, according to the automatic placement and routing method of the present invention, the amount of crosstalk received by a certain wiring from another wiring is calculated, and the amount of crosstalk exceeds a predetermined allowable value. When the calculated crosstalk amount exceeds the allowable value, the wiring path having the crosstalk amount is divided and a buffer is inserted in the middle.

According to an embodiment of the present invention, the amount of crosstalk is calculated by calculating a parasitic capacitance value between the certain wiring and the other wiring.

According to another embodiment of the present invention, when calculating the amount of crosstalk that a certain wiring receives from another wiring, the certain wiring is different from a wiring adjacent to the certain wiring in the same layer and a different wiring. The amount of crosstalk received from a wiring in a layer that is parallel or intersected with the certain wiring is calculated.

[0019]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of one embodiment of the automatic placement and routing apparatus of the present invention, and FIG. 2 is a flowchart showing the operation of the automatic placement and routing apparatus of FIG.

The automatic placement and routing apparatus according to this embodiment includes an input unit 101, a function block placement unit 102, a net routing unit 103, a crosstalk amount calculation unit 104, a crosstalk determination unit 105, a buffer insertion unit 106 , An arrangement and wiring information storage unit 107, an output unit 108, and a control unit 109.

The input unit 101 reads a wiring list.

The functional block arranging unit 102 arranges the unarranged functional blocks stored in the arrangement and wiring information unit 107 based on the wiring list.

The net wiring section 103 performs wiring of the non-net wiring stored in the arrangement / wiring information section 107 based on the wiring list.

The crosstalk amount calculator 104 calculates the amount of crosstalk received from the parallel wiring or the cross wiring in the adjacent wiring in the same layer and the wiring between different layers from the wiring route information of the wiring stored in the arrangement wiring information storage 107. It is calculated for each wiring.

The crosstalk amount determination section 105 determines whether or not the crosstalk amount of each wiring calculated by the crosstalk amount calculation section 104 does not exceed a predetermined allowable value.

The buffer insertion unit 106 inserts a buffer into the wiring path of the wiring exceeding the allowable value in the crosstalk amount determining unit 105 to divide the wiring. Then, the information of the divided wiring and the arrangement information of the inserted functional block are stored in the arrangement and wiring information storage unit 107.

The arrangement / wiring information storage unit 107 stores the arrangement information of the functional blocks, the wiring path information of the wiring, and the amount of crosstalk of the wiring.

The output unit 108 outputs the layout and wiring information stored in the layout and wiring storage unit 107.

The control unit 109 performs overall control such as activation of each function described above.

Next, the operation of this embodiment will be described with reference to FIGS.

First, the control unit 109 controls the input unit 1
01 is started. The input unit 101 reads the wiring list and stores the wiring connection information in the layout and wiring information storage unit 107.
And notifies the control unit 109 of the end of the process (step 201). Next, the control unit 109 receives the end notification from the input unit 101, and activates the functional block arrangement unit 102. The function block placement unit 102 places the unplaced function blocks based on the information stored in the placement and routing information storage unit 107. In addition, an arrangement position overlap check of the arranged function blocks is performed, and the position of the violating function block is corrected. Then, the arrangement result of the functional blocks is stored in the arrangement and wiring information storage unit 107, and the end of the processing is notified to the control unit 109 (step 202).

The control unit 109 is a function block arrangement unit 102
, The net wiring unit 103 is activated. The net wiring unit 103 includes a placement and routing information storage unit 107
Based on the information stored in, the non-net wiring is performed, the wiring route result of the wiring is stored in the layout and wiring information storage unit 107, and the end of the processing is notified to the control unit 109 (step 203).

The control unit 109 receives the end notification from the net wiring unit 103 and activates the crosstalk amount calculation unit 104. The crosstalk amount calculation unit 104 obtains, from the wiring route information of the wiring stored in the layout and wiring information storage unit 107, the crosstalk received from the same layer wiring adjacent to each wiring and the wiring parallel or crossing in different layers. Calculate the amount.

The calculation of the amount of crosstalk is performed by calculating the parasitic capacitance caused by the wiring being wired in parallel or crossing. As a calculation method, a parallel or intersecting area in the adjacent wiring and the different-layer wiring in the same layer is obtained, and the capacitance value Ccap is obtained from the area. The capacitance value Ccap is generally represented by the following equation (1).

Ccap = ε ₀ × ε _r × A ÷ d (1) where A is the area of the facing wiring, d is the distance from the facing wiring and corresponds to the thickness of the insulating film, ε _r is the relative dielectric constant of the insulating film, and ε ₀ is the dielectric constant in a vacuum.

If there are a plurality of adjacent wirings in the same layer and a plurality of parallel or intersecting wirings in different layers,
The sum of the respective capacitance values is the capacitance value Ccap.

Then, the crosstalk amount calculator 104 calculates
The calculated crosstalk amount for each wiring is stored in the layout and wiring information storage unit 107, and the control unit 109 is notified of the end of the processing (step 204).

The control unit 109 receives the end notification from the crosstalk amount calculation unit 104, and receives the crosstalk amount determination unit 1
05 is started. The crosstalk amount determination unit 105 extracts the crosstalk amount for each wiring stored in the arrangement / wiring information storage unit 107, compares it with a preset allowable value of the crosstalk amount, and exceeds the allowable value. The errored wiring is stored as an error in the arrangement and wiring information storage unit 107, and the control unit 109 is notified of the end of the process and also notified of whether or not there is any wiring whose crosstalk amount exceeds an allowable value (step 205).

Here, the comparison between the crosstalk amount of each wiring and the allowable value is used to determine whether an error has occurred using the following equation (2).

Ccap ≧ Cmax (2) Here, Ccap represents the capacitance value of the wiring calculated by the crosstalk amount calculation unit 104, and Cmax represents the allowable value of the crosstalk amount.

The control unit 109 includes a crosstalk amount determination unit 1
If a notification indicating that there is no wiring in which the crosstalk amount exceeds the allowable value does not exist, the output unit 108 is activated.
Then, the output unit 108 outputs the placement and routing information stored in the placement and routing information storage unit 107 (Step 20).
7).

In step 205, when it is received from the crosstalk amount determination unit 105 that there is always a line in which the crosstalk amount of the line exceeds the allowable value, the control unit 10
9 activates the buffer insertion unit 106. Then, the buffer insertion unit 106 extracts the information of the wiring in which the crosstalk amount of the wiring exceeds the allowable value stored in the arrangement / wiring information storage unit 107 and considers the allowable value for each wiring, and A buffer is inserted in the middle of the process to divide the wiring. Then, the buffer insertion unit 108 stores the wiring information obtained by dividing the wiring and the buffer insertion information in the arrangement wiring information storage unit 10.
7 and notifies the control unit 109 of the end of the process (step 206). In the control unit 109, the buffer insertion unit 1
Steps 202 to 20 upon receiving the end notification from
The processing up to 5 is repeated until the crosstalk amount falls within the allowable value in the processing of step 205.

Next, an application example according to the present embodiment will be described with reference to FIGS. FIG. 3 shows an initial wiring pattern. Here, the wiring 309 for which the amount of crosstalk is focused is a function block 301 and a function block 302.
Are connected. Also, the wirings 32 to 32
Reference numeral 3 denotes a wiring for connecting the functional blocks 303 to 308. The wiring 320 to the wiring 323 are wired adjacent to the wiring 309. Here, wiring 3
09 denotes wiring 320, wiring 321, wiring 322, wiring 3
It is assumed that the crosstalk amount received from 23 exceeds an allowable value.

FIG. 4 shows a wiring pattern after the present embodiment is applied to FIG. In FIG. 4, the wiring 310, the wiring 31
1. The wiring 312 is provided on the wiring path of the wiring 309 by the buffer 3
13 is a wiring divided by inserting the buffer 13 and the buffer 314.
Since the wirings 310, 311, and 312 divided by inserting the buffers 313 and 314 into the wiring 309 have shorter wiring lengths, the amount of crosstalk with the wirings 320 to 323 should not exceed an allowable value. it can.

Another application example according to the present embodiment will be described with reference to FIGS. 5 and 6. FIG.

In FIG. 5, wiring 4 from inverter 410
The case where the present embodiment is applied to the embodiment 04 will be described. Here, the wirings 404 are adjacent to the wirings 401 to 403.
It is assumed that the amount of crosstalk increases due to the influence of, and exceeds a predetermined allowable value.

FIG. 6 shows a circuit after applying the automatic placement and routing apparatus of this embodiment to the circuit of FIG.

In FIG. 6, the wiring 404 in FIG. 5 is divided, and in the middle thereof, an inverter 408 as a buffer is provided.
409 is inserted. The wiring 404 is the wiring 4
05 to 407, and the wiring length is shortened. Thus, the amount of crosstalk between the wiring from the inverter 410 and the wirings 401 to 403 is reduced.

As described above, in the present invention, a buffer is inserted in the middle of the wiring path of a wiring in which the amount of crosstalk exceeds an allowable value to divide the wiring, thereby shortening the wiring length of the wiring, and And the amount of crosstalk between adjacent wirings in the same layer and other wirings in parallel or crossing between different layers can be reduced.

[0051]

As described above, according to the automatic placement and routing method of the present invention, it is checked whether or not the amount of crosstalk does not exceed an allowable value for each wiring. Is that, by inserting a buffer in the middle of the wiring route of the wiring and dividing the wiring, the wiring length of each wiring can be shortened, and the amount of crosstalk between the wiring and other wirings can be reduced. Has an effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an automatic placement and routing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the automatic placement and routing apparatus of FIG. 1;

FIG. 3 is a circuit diagram before application of the automatic placement and routing apparatus of FIG. 1;

4 is a circuit diagram of the circuit diagram of FIG. 3 after application of the automatic placement and routing apparatus of FIG. 1;

FIG. 5 is a circuit diagram before applying the automatic placement and routing apparatus of FIG. 1;

6 is a circuit diagram after applying the automatic placement and routing apparatus of FIG. 1 to the circuit diagram of FIG. 5;

FIG. 7 is a diagram for explaining a wiring pattern that receives crosstalk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Input part 102 Functional block arrangement part 103 Net wiring part 104 Crosstalk amount calculation part 105 Crosstalk amount judgment part 106 Buffer insertion part 107 Arrangement wiring information storage part 108 Output part 109 Control part 201-207 Step 301-308 Function block 309 To 312 wiring 313, 314 buffer 320 to 323 wiring 401 to 407 wiring 408 to 410 inverter 501 to 505 wiring 506, 507 wiring grid

Claims (6)

(57) [Claims] 1. A crosstalk amount calculating means for calculating a crosstalk amount received by a certain wiring from another wiring, and whether a crosstalk amount calculated by the crosstalk amount calculating means exceeds a predetermined allowable value. A crosstalk amount determining means for determining whether or not the calculated crosstalk amount exceeds the allowable value; and a buffer inserting means for dividing a wiring path having the crosstalk amount and inserting a buffer in the middle thereof An automatic placement and routing apparatus having: 2. The automatic placement and routing apparatus according to claim 1, wherein the crosstalk amount calculation means calculates a crosstalk amount by calculating a parasitic capacitance value between the certain wiring and the other wiring. 3. The crosstalk amount calculating means calculates a crosstalk amount received by the certain wiring from a wiring adjacent to the certain wiring in the same layer and a wiring parallel or crossing the certain wiring in a different layer. Item 1
Or the automatic placement and routing apparatus according to 2. 4. A method for calculating the amount of crosstalk received by a certain wiring from another wiring, determining whether the amount of crosstalk exceeds a predetermined allowable value, and calculating the calculated amount of crosstalk based on the allowable value. , The wiring route having the crosstalk amount is divided and a buffer is inserted in the middle of the route. 5. The automatic placement and routing method according to claim 4, wherein the amount of crosstalk is calculated by calculating a parasitic capacitance value between the certain wiring and the other wiring. 6. When calculating the amount of crosstalk that a certain wiring receives from another wiring, the certain wiring is a wiring adjacent to the certain wiring in the same layer and a wiring parallel or crossing the certain wiring in a different layer. 6. The automatic placement and routing method according to claim 4, wherein the amount of crosstalk received from the computer is calculated.