Browse Prior Art Database

Groups of Three Macro Positioning

IP.com Disclosure Number: IPCOM000047402D
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 34K

Publishing Venue

IBM

Related People

Caldwell, LB: AUTHOR [+4]

Abstract

Circuit systems (macros) are positioned in groups in which the parallel space between two macros is blocked by the side of a third macro on an integrated circuit substrate. Other macros are positioned in relation to macros in one such group so as to have the same configuration. The arrangement avoids wasted space. Primary wiring is by long metal connections parallel to the sides of the macros. Non-metal connections are short and perpendicular to those lines, to thereby minimize non-metal connections. In such chip technologies, a single metal plane is available, plus a second undesirable plane (typically by diffusion or polysilicon). Also on such chips, the basic circuit systems (macros) may very much exceed in size and number of node connections a typical logic circuit, such as a three-way NOR.

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Groups of Three Macro Positioning

Circuit systems (macros) are positioned in groups in which the parallel space between two macros is blocked by the side of a third macro on an integrated circuit substrate. Other macros are positioned in relation to macros in one such group so as to have the same configuration. The arrangement avoids wasted space. Primary wiring is by long metal connections parallel to the sides of the macros. Non-metal connections are short and perpendicular to those lines, to thereby minimize non-metal connections. In such chip technologies, a single metal plane is available, plus a second undesirable plane (typically by diffusion or polysilicon). Also on such chips, the basic circuit systems (macros) may very much exceed in size and number of node connections a typical logic circuit, such as a three-way NOR. Often macros on a given chip may vary greatly in size, although they are usually rectangular in shape. Wires connecting two macros typically require electrical access to specified positions at the perimeter of each macro, as shown in Fig. 1. Very often an effort is made to arrange such macros to achieve a very regular configuration, such as rows and columns. Such rows and columns are shown in Fig. 2, suggestive of the city block arrangement with intermediate straight streets. The basic symmetry and systematic structure of the city block arrangement are often assumed to be an advantage. Four-way intersections, such as shown in Fig. 3, abound. On an integrated circuit, however, nothing corresponding to the traffic lights of city streets is available. On a chip with a four-way intersection where lines would pass through the intersection both left and right and up and down, some underpass arrangement is necessary on the less desirable non-metal plane. A second undesirable feature of row and column arrangement exists. The basic building blocks vary greatly in size. The long, straight intersecting streets are suited to generally uniform block sizes. The different sized macros will not fit well in uniform city block regions, and considerable space is wasted, as shown in Fig. 4. Smaller macros, although rectangularly shaped, do not utilize all the space in regions between the streets. The four-way intersection is therefore to be avoided, but by a consistent approach so as to avoid situations ultimately leaving only such intersection available. This is achieved by a design approach using a three-way intersection. Consider Fi...