Fast Timing Library Characterization Through Selective Use of Regression Models

Timing behavior of standard cells is represented as two-dimensional tables in a timing library, where each table entry is obtained through transistor-level simulation. As technology scales, the number of design corners and standard cells has increased dramatically, leading to a substantial increase in simulation time for timing characterization. This may delay the design schedule or impose additional demands on tool licenses. To address this challenge, we propose a fast timing characterization method that selectively uses transistor-level simulation and model-based prediction. In this method, a subset of table entries is obtained through simulation, while the remaining entries are predicted by regression models trained on the simulated data. Multiple regression models are employed to capture the diverse characteristics of each entry location, and the most accurate model for each entry is identified at one corner, called an anchor corner. The selected models are then used to predict the corresponding entry at target corners. Experimental results show that the proposed method achieves high accuracy with a 40% reduction in runtime; the mean and 3-sigma absolute errors are 0.4% and 2.3%, respectively, representing a significant improvement over conventional methods. The accuracy of the proposed method is further validated on 7-nm technology libraries.