JP2991389B2 - LSI automatic layout device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LSI automatic layout apparatus, and more particularly to an LSI automatic layout apparatus using a multi-layer aluminum wiring process and using megacells having different heights and widths.

[0002]

2. Description of the Related Art A conventional LSI automatic layout apparatus using a multilayer metal (aluminum) wiring process includes a CPU,
ASIC (Application Specialization) using a standard LSI such as ROM and RAM as a megacell
ic Integrated Circuit (IC for specific application).

The processing in this LSI automatic layout apparatus uses connection information (hereinafter referred to as a netlist) indicating the connection between the megacells and cell library information indicating the outer shape and the terminal position of the megacell. After a position (hereinafter referred to as a floor plan) is determined, a wiring layout is performed between external terminals of the megacell according to a netlist.

FIG. 2 is a block diagram showing a layout in which wiring layout has been performed by a conventional LSI automatic layout apparatus. In FIG. 2, after the floor plan of the megacell is determined, the external terminals 56, 57, and 5 of the megacell A79 are provided.
Reference numerals 8 and 59 are connected to external terminals 72, 73, 74 and 75 of the megacell C81 by wires 52, 53, 54 and 55 in accordance with the netlist to be input. At this time, the coordinates defined in the cell library were directly used for the terminal positions of the megacell.

The external terminals 69, 70, 7 of the megacell B80
1 is connected to the terminals 76, 77, 78 of the megacell C81 by wires 60, 61, 62, respectively, and the external terminals 79, 80, 81 of the megacell D82 are connected to the terminals 6 of the megacell A79.
6, 67, 68 via wiring 63, 64, 65.

[0006]

SUMMARY OF THE INVENTION Such a conventional LS
In the automatic layout system, the wiring layout is performed not only for the channel router or the maze router, which is the algorithm of the wiring system, but also for the terminal position of the megacell defined in the cell library. However, there is a disadvantage that the chip size increases due to an increase in the wiring area.

In order to solve this drawback, a structure was conceived in which the upper part of the megacell was made a wirable area by a multi-layer aluminum wiring process. However, it has a disadvantage that it cannot be used, and remains as an unused wiring area.

An object of the present invention is to provide an LSI automatic layout apparatus which solves the above-mentioned drawbacks, does not increase the chip size, and does not create an unused wiring area.

[0009]

An LSI automatic layout apparatus according to the present invention is capable of determining the outer shape of a megacell and the positions of external terminals.
Cell library information to represent the connection between megacells
Means for Determining Megacell Arrangement Position Using Connection Information
According to the connection information
LSI automatic layout device having means for performing
After determining the location of the multiple megacells,
Outside of each of the first megacell and the second megacell to be
Determine whether the position of the external terminal exists at the opposite coordinates
Means, an external terminal of the first megacell and a second megacell
When the external terminals of
Virtual externals on the opposite outer frames of the
Means for providing a terminal, and a virtual device provided in the first megacell.
An external terminal and a virtual external terminal provided in the second megacell.
Means for connecting the first megacell to the external terminal and the virtual external
And the external terminal in a wiring region above the first megacell.
Means, an external terminal and a virtual external terminal of the second megacell,
In the wiring area above the second megacell;
Characterized in that it comprises a.

[0010]

FIG. 1 is a block diagram of a layout by an LSI automatic layout apparatus according to one embodiment of the present invention.

In FIG. 1, in the LSI automatic layout apparatus of the present embodiment, after the floor plan of the mega cell is determined, the external terminals 23 and 24 of the mega cell A1 defined on the netlist are determined.
24, 25, 26 and the external terminals 40, 4 of the megacell C3.
It turns out that there is no external terminal on the outer frame of the megacell facing 1, 42 and 43.

For this reason, using virtual external terminal generating means,
The virtual external terminals 48, 49, 50, 51 of the megacell A1 and the virtual external terminals 44, 45, 46, 47 of the megacell C3 are generated on the opposing megacell frames of each megacell.

The generated virtual external terminal is connected to the virtual external terminal 48 of the megacell A1 using virtual external terminal connection means.
49, 50, 51 and the virtual external terminal 4 of the megacell C3
Wiring connections with 4, 45, 46, 47
Step 8

Thereafter, the external terminals 23, 2 of the megacell A1
4, 25, 26 and virtual external terminals 48, 49, 50, 5
1. The external terminals 40, 41, 42, 43 of the megacell C3 and the virtual external terminals 44, 45, 46, 47 are connected by virtual external terminal connection means.

The terminals 34, 35, 36 of the megacell B2
Are the wirings 9, 10, 11 and the terminals 37,
38, 39 and the terminals 31, 3 of the megacell D4.
2, 33 is a wiring 12, 13, 14, Ru is connected to the terminal 28, 29, and 30 of the mega-cell A1.

[0016]

As described above, in the LSI automatic layout apparatus of the present invention, it is possible to change the position of the external terminals of the megacell after the floor plan is determined, and the wiring area generated due to extra wiring wraparound and the like. Can be prevented, and as a result, the chip size can be reduced.

According to the present invention, the position of the external terminal is changed by using the wiring region above the megacell, which has not been effectively used even by using the conventional multi-layer aluminum wiring process. No effect on size.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a layout by a conventional automatic layout device.

[Explanation of symbols]

1,2,3,4,79,80,81,82 Megacell 5,6,7,8,9,10,11,12,13,14,
Wiring between 52, 53, 54, 55 megacells 23, 24, 25, 26, 28, 29, 30, 31, 3
2,33,34,35,36,37,38,39,4
0, 41, 42, 43, 66, 67, 68, 69, 7
0, 71, 72, 73, 74, 75, 76, 77, 7
8, 79, 80, 81 megacell external terminal 44, 45, 46, 47, 48, 49, 50, 51
Megacell virtual external terminals 15, 16, 17, 18, 19, 20, 21, 22
Wiring between external terminals and virtual terminals

Claims (1)

(57) [Claims] 1. The external shape of a megacell and the positions of external terminals
Cell library information to represent the connection between megacells
A method for determining an arrangement position of the megacell using the connection information
And the arrangement of the megacells according to the connection information.
LSI automatic layout having means for performing line layout
In winding device, after determining the arrangement positions of the plurality of mega-cells, it is connected
External to each of the first megacell and the second megacell to be
Determines if terminal location is at opposite coordinates
Means, external terminals of said first megacell and said second megacell.
If the external terminal does not exist at the opposing coordinates,
Virtual outside on the opposite outer frame of the second and the second megacell
Means for providing an external terminal; a virtual external terminal provided on the first megacell;
For connecting to virtual external terminals provided in the 2 megacells
A stage, the external terminal and the virtual external terminal of the first megacell
Means for connecting the first and second megacells in a wiring area above the first megacell
And the external terminal of the second megacell and the virtual external
The terminal is connected to the wiring area above the second megacell.
Means for automatically laying out an LSI.