Computer-aided design and analysis of circuits and semiconductor – Integrated circuit design processing – Physical design processing
Reexamination Certificate
2011-07-19
2011-07-19
Whitmore, Stacy A (Department: 2825)
Computer-aided design and analysis of circuits and semiconductor
Integrated circuit design processing
Physical design processing
C716S118000, C716S122000, C716S123000, C716S124000, C716S125000, C716S132000, C716S135000
Reexamination Certificate
active
07984410
ABSTRACT:
A placer produces a global placement plan specifying positions of cell instances to be interconnected by nets within an integrated circuit (IC) by initially clusterizing cell instances to form a pyramidal hierarchy of blocks and generating an initial global placement plan specifying a position of each block at a highest level of the hierarchy. The placer then declusterizes the global placement plan by replacing the highest level blocks with their component blocks and then improves the routability of the global placement plan by iteratively moving specified block positions in directions and by distances dynamically determined by analyzing the global placement plan and an objective function having a total wirelength term and having a bin density term reflecting density of blocks in specified areas (bins) of the IC. The placer iteratively repeats the declusterization and routability improvement process until the global placement plan specifies positions of all blocks residing at the lowest level of the hierarchy, with weighting of the bin density term adjusted when necessary during each iteration of the routability improvement process to provide sufficient white space in each bin. The placer employs a look-ahead legalization technique to move low level blocks to legal positions during later iterations of the plan improvement process.
REFERENCES:
patent: 6282693 (2001-08-01), Naylor et al.
patent: 2003/0196183 (2003-10-01), Alpert et al.
patent: 2006/0190889 (2006-08-01), Cong et al.
Chen Tung-Chieh
Jiang Che-Wei
Springsoft USA, Inc.
Whitmore Stacy A
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