Distribution dependent clustering in buffer insertion of high fanout nets
US6487697B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 28, 2001 |
| Grant date | Nov 26, 2002 |
| Priority date | — |
| Expiry date | Jun 13, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F30/327
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Methods and apparatus are disclosed for inserting buffers into the design of an integrated circuit with a high fanout net. If a net has a ramptime violation, all of the driven elements in the net are clustered in such a manner that the total load (capacitance) of the driver decreases. Clustering is based upon a two-dimensional partitioning approach together with three proposed heuristics (expand, shrink and merge), which iteratively partitions the placement regions of the net such that the number of buffers to be inserted and the level of inserted buffer tree are minimized. After clustering, one buffer is inserted for each cluster created in the clustering operation. Each of the inserted buffers drives its corresponding cluster. The buffers that are inserted will not have any ramptime violation, which ensures converge of the buffer insertion scheme. Therefore, each insertion of a level of buffers reduces the overall ramptime of the net. After insertion of a level of buffers, the ramptime of the net is checked once again. If it is still not acceptable, the aforementioned clustering and insertion are repeated and the above cycle is iterated until there is no ramptime violation. Durin…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.