Browse Prior Art Database

Method and Apparatus for Application Independent Dynamic Program Controlled Cell Resizing

IP.com Disclosure Number: IPCOM000193138D
Original Publication Date: 2010-Feb-11
Included in the Prior Art Database: 2010-Feb-11
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Abstract

Chip design automation tools use a physical rule to define a cell's shape. This rule defines a real fixed shape for the cell. For any of a number of design reasons it is sometimes to the designer's advantage to be able to adjust the modeled size of placeable cells. Historically design systems have defined these size constraints as physical expansion factors within a specific placement tool implementation. Because these expansion factors are implemented directly within a specific tool, it is difficult to honor these constraints across multiple tools that may have different expansion constraint definitions or no constraint definition at all. Typically these constraints are also limited to only expand the placeable cells. Because of the historically tool based implementation of these constraints, design flows dependent on a consistent view of the size of a cell become difficult or impossible to manage. This invention addresses these limitations by allowing Alternate Physical Shapes to be defined directly in the in-core model (database). By implementing these alternate physical shapes directly in the model, we can use the model itself to pass consistent alternate shapes to any application or set of applications calling for shape data. Shape controls can be used to both grow or shrink a cell or even change a non rectangular shape to a rectangular one for early exploratory work.

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Method and Apparatus for Application Independent Dynamic Program Controlled Cell Resizing

Asic Cell libraries by their very nature are static in their definition and involve a long turn around time for getting new ones.

Currently there are size constraints in some application today but are limited to
1) not under user control ....
2) limited to making things larger or
3) only work within the placement code they were designed for

This invention was created to address these shortcomings.
1) Users have direct control of what size any or all of the library cells are.
2) Users control which size is in effect, Actual size or Alternate size.
3) They can either make the cells larger or smaller as necessary to fit the needs of the application at any point in an overall flow.
4) They can even make all the cells the same size or change complex shapes into a rectangle.
5)

New cell definitions can be utilized before the official rules are released.

6) Users can change the cell sizes any time during a flow to facilitate a downstream tool success.

7) Implemented in such a way as to make it usable for all tools that use physical information.

This creates an environment where exploration of the design can be done with fewer or more restrictions of the physical solution depending on the desired outcome.

Popular examples known so far:

- Make all the cells smaller to be able to see the timing result if the design could actually fit in the space allocated for it.

- Complement the Xfactor/Blowup result for cells...