ExtensiveSlackBalance: an approach to make front-end tools aware of clock skew scheduling

In the traditional ASIC flow, clock skew scheduling (CSS), as a method to improve timing, is usually employed during the CTS (clock tree synthesis) step while front-end tools do not take clock skew as a manageable resource. This limits the potential of the subsequent CSS. To overcome such limitations, we design an enhanced CSS algorithm ExtensiveSlackBalance and integrate it into the back-annotation and re-optimization iterations of the current industrial flow. Experiment results show that, the clock frequency can be improved to 26.2% on average compared to 6.4% in the traditional ASIC flow.