JPH05315452A - Circuit pattern layout design system of integrated circuit device - Google Patents

Abstract

PURPOSE:To readily determine whether or not an arrangement position of a circuit block is good by enabling display of a rat nest which is a virtual line between time circuit block and other end circuit block of a signal path which forms a pair therewith when arranging operators for the circuit block which becomes one end of the signal path. CONSTITUTION:A signal path whereto a designation circuit block which is an arrangement object belongs is extruded by a path extracting means 4. Path trace is carried out in a forward direction of an extracted signal path from the designation circuit block, a line is drawn virtually between an arranged circuit block which appears first and the designation circuit block, it is displayed by a virtual line display means 7 and a rat nest is displayed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a circuit pattern layout design system for an integrated circuit device (LSI), and more particularly to an LSI circuit pattern layout design system for interactively designing a layout of a circuit pattern of an LSI by a CAD method.

[0002]

2. Description of the Related Art In a conventional pattern layout design system of this type, a designer decides the layout of circuit blocks while looking at the layout display on the screen. In this case, the circuit blocks are connected to the net. In order to easily identify the positional relationship with other circuit blocks,
The blocks are displayed by connecting them with virtual straight lines (hereinafter referred to as rat nests). The designer refers to the displayed circuit blocks and the rat nests between them to judge the quality of the block layout position.

In the layout design of an LSI, circuit blocks to be signal path start points and end points may be manually arranged in advance before automatic layout processing is performed. The purpose is to control the placement position of the blocks on the path that is placed by the automatic placement processing by fixing the placement positions of the blocks that are the start and end points of the pass, and prevent the path route from becoming long. Done. Therefore, when manually placing a block that is the start point (or end point) of a path, the end point (or start point) of the path that forms a pair with that block
Information on the positional relationship with the block is required.

In the conventional interactive layout method, rat nests are displayed for the purpose of determining the positional relationship between blocks, but this rat nest can be displayed only between blocks connected by a net. Therefore, in the case of blocks that are the start and end points of a path, the rat nest cannot be displayed because a plurality of nets and blocks are interposed between them. For this reason, the positional relationship between the block that is the start point and the block that is the end point of the path cannot be determined, making it difficult to judge the placement position of the circuit block, which requires the experience of the designer and the design man-hours. Has the drawback of increasing.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to display a rat nest between each circuit block at the start point and the end point of a signal path in order to facilitate determination of the positional relationship between circuit blocks. It is to provide a circuit pattern layout design system of.

[0006]

A circuit pattern layout design system for an LSI according to the present invention has a predetermined signal path, circuit blocks located at both ends of the signal path, circuit blocks located in the middle of the signal path, and signals to these circuit blocks. Storage means for storing path information such as propagation order transmitted, means for extracting a signal path to which the designated circuit block belongs from the storage means in response to designation of a circuit block to be arranged, and the extracted signal path Path trace means for detecting the arranged circuit block which appears first by tracing the specified circuit block as a starting point, and virtually connects the detected arranged circuit block and the specified circuit block with a straight line. Means for displaying the arranged circuit blocks, the designated circuit blocks, and the straight lines between these circuit blocks. Characterized in that it comprises a display means.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a system block diagram of an embodiment of the present invention. The placement information storage means 9 stores the placement information regarding the already placed circuit blocks. The path information storage means 8 stores signal path information regarding a signal path that needs to take delay time into consideration,
Circuit blocks located at both ends (start point and end point) of the signal path, circuit blocks located in the middle of the signal path,
Information indicating the order of propagation of signals in these circuit blocks is stored.

The layout state storage means 2 displays the current layout state of the circuit blocks on a display screen of a CRT or the like, and the read information from the layout information storage means 9 is displayed.

The arranging means 3 arranges the designated circuit block at a designated position in response to the designation of the circuit block to be arranged by the designer. The path extraction means 4 extracts the signal path to which the arranged designated circuit block belongs from all paths.

The forward direction arranged block detecting means 5 performs a path trace in the signal propagation direction (forward direction) on the extracted path starting from the designated circuit block to find the first arranged block. Further, the backward arranged block detecting means 6 performs a path trace in the direction opposite to the signal propagation direction from the designated circuit block as a starting point for the extracted path, and finds the arranged block that appears first.

The virtual straight line display means 7 virtually connects the designated circuit block and the circuit block (already arranged) found by the forward and backward arranged block detecting means 5 and 6 by a straight line and displays it. Is.

The operation of the embodiment of the present invention will be described with reference to the concrete examples of FIGS. FIG. 2 is an image showing an example of the path information stored in the path information storage means 8, and 31 to 33 show signal paths for which delay time needs to be taken into consideration.

The signal path 31 includes circuit blocks 11, 21, 21.
The signal propagates in the order of 22 and 12, the signal path 32 propagates in the order of the circuit blocks 12, 23, 24 and 13, and the signal path 33 comprises the circuit blocks 12, 25 and 2.
It is assumed that the signal propagates in the order of 6 and 14.

FIG. 3 shows an image of the placed circuit block information stored in the placement information storage means 9 at the present time. The circuit block 11 on the signal path shown in FIG.
Only 13 and 14 have been placed.

In this state, the designer next moves on to the circuit block 1
A case in which two are arranged will be described below. It is assumed that the designer arranges the circuit block 12 at the position shown in FIG. At this time, the paths 31 to 31 are determined as the signal paths to which the block 12 belongs by the path extracting means 4.
33 is extracted. For the subsequent processing, refer to the signal path 32.
Will be described as an example.

For the signal path 32, a path trace is performed in the signal propagation direction (forward direction) from the block 12 by the forward direction arranged block detecting means 5, and the blocks 23,
The blocks 24 and 13 are sequentially recognized, and the block 13 is detected as the first placed block that appears. Then, the virtual straight line display means 7 displays the straight line 42 shown in FIG. 4 between the blocks 12 and 13.

Next, the signal path 32 is subjected to path tracing in the direction opposite to the signal propagating direction by the backward direction arranged block detecting means 6. In this example, the block 12 is used.
Is the start point of the signal path 32, the placed block is not detected even if the backward trace is performed. Therefore, no display is made at this time.

The same processing is performed on the signal paths 31 and 33, respectively, and the straight lines 41 and 43 shown in FIG. 4 are displayed between the blocks 11 and 14 and the block 12, respectively. Therefore, the designer can use these virtual straight lines 41 to 41.
By referring to the display of 43, it becomes easy to judge whether the position of the circuit block 12 to be arranged is good or bad.

[0020]

As described above, according to the present invention, when a circuit block at one end of a signal path is manually arranged, it is placed between the block and the other end circuit block of the signal path forming a pair. Since it is possible to display a virtual straight line, the positional relationship between the circuit block to be placed and another circuit block can be easily determined, and the number of designers can be reduced.

[Brief description of drawings]

FIG. 1 is a system block diagram of an embodiment of the present invention.

FIG. 2 is an image showing an example of path information stored in a path information storage means 8.

FIG. 3 is a diagram showing a display example of an arrangement state of circuit blocks.

FIG. 4 is a diagram showing a layout example of circuit blocks and a display example of a rat nest.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 control means 2 arrangement | positioning state display means 3 arrangement | positioning means 4 path extraction means 5 forward direction arrangement | positioning block detection means 6 reverse direction arrangement | positioning block detection means 7 virtual straight line display means 8 path information storage means 9 arrangement | positioning information storage means 11-14 circuit Blocks 31-33 Signal paths 41-43 Rat nest

Claims (3)

[Claims] 1. Storage means for storing path information such as a predetermined signal path, circuit blocks located at both ends of the signal path, circuit blocks located in the middle of the signal path, and propagation order of signals transmitted to these circuit blocks. And a means for extracting the signal path to which the specified circuit block belongs from the storage means in response to the specification of the circuit block to be arranged, and tracing the extracted signal path with the specified circuit block as a starting point. Path trace means for detecting the arranged circuit block appearing in, a means for virtually connecting the detected arranged circuit block and the designated circuit block with a straight line, the already arranged circuit block, A circuit pattern of an integrated circuit device including a designated circuit block and display means for displaying the straight line between these circuit blocks. Layout design system. 2. The path trace means has a forward trace means for tracing in a forward direction and a backward trace means for tracing in a reverse direction with respect to a propagation order of the signal path. 2. A circuit pattern layout design system for an integrated circuit device according to 1. 3. The signal path according to claim 1, wherein the signal path is a path that needs to take a delay time into consideration.
A circuit pattern layout design system for an integrated circuit device according to claim 1.