Characterizing sequential cells using interdependent setup and hold times, and utilizing the sequential cell characterizations in static timing analysis
US7774731B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 17, 2008 |
| Grant date | Aug 10, 2010 |
| Priority date | — |
| Expiry date | Feb 9, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F30/3312
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A sequential cell is characterized using interdependent setup/hold time pairs to produce associated clock-to-Q delay values, and then identifying setup/hold time pairs that produce a selected clock-to-Q delay value (e.g., 10% of failure). The identified setup/hold time pairs (or a piecewise linear (PWL) approximation thereof) are then stored in a cell library for use in static timing analysis (STA). During STA, the setup and hold skews calculated for each synchronous circuit are compared with a selected setup/hold time pair stored in the cell library (e.g., a pair having a relatively low hold value). If at least one of the setup and hold skews violates the selected setup/hold time pair, then the remaining identified setup/hold time pairs (or the PWL approximation) are utilized to determine if the synchronous circuit is violates established constraints, and if not, to identify the setup and hold times required to remove the violation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.