JP2538565B2 - Automatic layout method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a standard cell type LSI layout.

(Prior Art) In a conventional standard cell LSI automatic layout, cells that are densely coupled are arranged close to each other and cells that are loosely coupled are arranged far from each other based on connection information between cells. On the other hand, when manually arranging standard cell type cells, pay attention to the fact that the adjacent cells on the left and right are arranged with the side faces closely spaced, and adjust the placement by making terminals on the side faces of the cells. It is possible to achieve connection of some signals by just doing so and to arrange so as to save the wiring area between cells. It is not possible to achieve a sophisticated layout such as manual layout with the automatic layout program described above. It was possible.

(Problems to be Solved by the Invention) As described above, in the above automatic layout method, it is impossible to arrange convenient cells adjacent to each other and separate inconvenient cells from each other. There was a problem. It is an object of the present invention to provide a method for providing optimum layout by giving attributes to cells even in automatic layout.

[Structure of Invention]

(Means for Solving Problems) In order to achieve the above object, in the present invention, an attribute relating to cell arrangement is given in an automatic layout system,
It is characterized in that an optimal layout is performed by arranging in consideration of the detailed information.

(Operation) If a cell requiring a flock signal and a different power supply voltage or the like is arranged at a distant place, wiring becomes complicated. If the cell attributes are taken into consideration and arranged as in the method of the present invention, the optimum arrangement similar to the manual arrangement is possible.

(Examples) Details of the present invention will be described below with reference to the drawings.

FIG. 1 is a layout diagram of an embodiment of the present invention. In this example, in addition to the power supply line (1), the clock signal line (2)
However, they are connected by making the side surfaces of the cells adjacent to each other. However, cells for standard cells include cells that do not require a clock signal, such as a logic gate, and cells that require a clock signal, such as a flip-flop. Therefore, these cells cannot be adjoined indefinitely. Therefore, as shown in FIG. 2, a cell (3) having no clock line and a cell (4) having a clock line are respectively registered in the library for a long time. Further, in order to connect the cell (3) having no clock line and the cell (4) having a clock line, the clock signal line (2) does not exist on one side surface and the clock signal line (2) does not exist on the other side surface. A switch box cell (5) in which the line (2) exists is prepared. Then, an attribute is given to the side surface of the cell so that the adjacent sides have the same attribute so that the clock signal line (2) is normally connected.
That is, in this example, the side surface where the clock signal line (2) is exposed is given an attribute of, for example, "C", and the side surface where the clock signal line (2) is not provided is given an attribute of, for example, "N". Therefore, as shown in FIG. 3, a cell (3) that does not require a clock signal has "N" on both sides, a cell (4) that requires a clock signal has "C" on both sides, and a switch box cell (5). Gives the attribute "N" to one side and "C" to the other.

When arranging cells, the cells are arranged so that only the side surfaces of cells having the same attribute are adjacent to each other. The actual placement procedure is, for example,
It looks like this: First, as shown in FIG. 4 (a), after arranging by the normal automatic layout method, the attributes around the cell,
In this case, the cell (4) with the clock signal and the cell (3) without the clock signal are replaced by the attribute information around the cell (b). If the matching is not obtained even after the replacement is performed (b), the switch box cell (5) is inserted between the non-matching adjacent sides (c). The first by this method
As shown, cells having a pattern can be aligned and arranged. When a storage element such as a flip-flop that uses a clock signal is arranged in an automatic layout system, it can be arranged at an optimum position by the arrangement method according to this embodiment, and a wiring area between cells can be connected.

Next, another embodiment different from the embodiment shown in FIG. 1 is shown in FIG.
This example is a case where cells requiring different voltages are arranged adjacent to each other, and cells (6) using a 5V power supply in the cell library, that is, attributes on both sides are arranged in the same manner as the embodiment of FIG. Is a cell (7) that uses a power supply of 5V (6) or 3V, that is, the attributes on both sides are 3V (7), or is it a switch box cell (8), that is, the attribute on one side is
This is an example in which an appropriate placement result equivalent to the hand placement is obtained by arranging in consideration of information as to whether the attribute of the other side of 5V is 3V (8).

〔The invention's effect〕

As described above, according to the present invention, the cells are arranged in consideration of the attributes around the cells so that a person can determine and arrange the situation, so that the wiring area between the cells can be saved and the complicated layout can be achieved. Can be automatically and optimally performed.

[Brief description of drawings]

FIG. 1 is a layout diagram of an embodiment of the present invention, FIG. 2 is a conceptual diagram of cells registered in a library, and FIG. 3 is a concept showing attributes around cells registered in the library. Fig. 4 is a diagram of cells arranged by the actual arrangement procedure, and Fig. 5 is a layout diagram in which cells requiring different voltages are arranged adjacent to each other, and a diagram showing attributes around the arranged cells. is there. 1 ... Power line, 2 ... Clock signal line, 3 ... Cell that does not require clock signal line, 4 ... Cell that requires clock signal line, 5 ... Switch box cell that connects 3 and 4, 6 …… A cell that requires a 5V power supply, 7 …… A cell that requires a 3V power supply, 8 …… A switch box cell that connects 6 and 7.

Claims (1)

(57) [Claims] 1. In a standard cell type LSI layout, the adjacency information for distinguishing the attribute of a side edge of a cell that is in contact with another cell on the side is given to the side edge of the adjacent cell in the cell library. The layout method is characterized in that the layout is performed while allowing the switch box cells to be inserted appropriately while permitting the combinations in which the attribute of is allowed and not allowing the combinations in which the attributes are not allowed.