METHOD OF ESTIMATING PATH DELAYS IN AN IC
Inventors: Pinhong Chen, Fremont, CA (US);
Chin-Chi Teng, Sunnyvale, CA (US)
Assignee: Cadence Design Systems, Inc., San
Jose, CA (US)
Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 202 days.
Appl. No.: 10/323,399
Filed: Dec. 18, 2002
Prior Publication Data
US 2003/0140325 Al Jul. 24, 2003
Related U.S. Application Data
Provisional application No. 60/342,009, filed on Dec. 18, 2001.
U.S. CI 716/6; 716/4
Field of Classification Search 716/6,
See application file for complete search history.
U.S. PATENT DOCUMENTS 5,379,232 A * 1/1995 Komoda 703/15
5,515,291 A * 5/1996 Omori et al 716/6
5,617,325 A * 4/1997 Schaefer 716/6
5,638,294 A * 6/1997 Sasada 716/5
5,654,898 A 8/1997 Roetcisoender et al.
5,754,826 A 5/1998 Gamal et al.
5,841,672 A * 11/1998 Spyrou et al 716/6
5,896,300 A * 4/1999 Raghavan et al 716/10
5,901,063 A * 5/1999 Chang et al 716/4
6,182,269 Bl* 1/2001 Laubhan 716/5
6,381,730 Bl* 4/2002 Chang et al 716/5
6,415,426 Bl * 7/2002 Chang et al 716/9
6,557,145 Bl 4/2003 Boyle et al.
6,643,831 Bl* 11/2003 Chang et al 716/4
6,854,099 Bl* 2/2005 Dewey et al 716/5
* cited by examiner
Primary Examiner—A. M. Thompson
(7'4) Attorney, Agent, or Firm—Daniel J. Bedell; Smith-Hill
To estimate path delays within an IC, a serial database is first created to hold and read out RC extraction data for nets within the IC in an order in which the RC extraction data will be needed when estimating path delays. Thereafter, as the RC extraction data is sequentially read out of the database for each net, the path delay though each section of the net is computed and added to the estimated path delay for each signal path including that net section. The RC extraction data for each net is accessed and accessed only once, thereby minimizing the processing time needed to perform timing analysis by minimizing hard disk read accesses when the RC extraction database resides on a hard disk.
16 Claims, 4 Drawing Sheets