Statistical corner evaluation for complex on-chip variation model

摘要

The invention provides a method for performing statistical static timing analysis using a novel on-chip variation model, referred to as Sensitivity-based Complex Statistical On-Chip Variation (SCS-OCV). SCS-OCV introduces complex variation concept to resolve the blocking technical issue of combining local random variations, enabling accurate calculation of statistical variations with correlations, such as common-path pessimism removal (CPPR). SCS-OCV proposes practical statistical min/max operations for random variations that can guarantee pessimism at nominal and targeted N-sigma corner, and extends the method to handle complex variations, enabling graph-based full arrival/required time propagation under variable compaction. SCS-OCV provides a statistical corner evaluation method for complex random variables that can transform vector-based parametric timing information to the single-value corner-based timing report, and based on the method derives equations to bridge POCV/SSTA with LOCV. This significantly reduces the learning curve and increases the usage of the technology, being more easily adopted by the industry.

主权项

1. A computer-implemented method of performing statistical static timing analysis (SSTA) comprising:
calculating a parametric arrival time of a data signal transmitted via a data path including a plurality of cells the parametric arrival time determined through an arrival time nominal value and an arrival time standard deviation value; calculating a parametric required time of the data signal based on a clock signal transmitted via a clock path, the parametric required time determined through a required time nominal value and a required time standard deviation value; calculating a corner slack value based on the parametric arrival time and the parametric required time, the corner slack representing an amount of time between an arrival time of the data signal and an arrival time of the clock signal; and determining, by a computer, specific delay shift values for a subset of the plurality of cells in the data path, such that a sum of the specific delay shift values of the plurality of cells matches the corner slack value.