A Platform of Resynthesizing a Clock Architecture Into Power-and-Area Effective Clock Trees

摘要

To trigger events for application-specific data transfer among registers in a multimillion-gate system-on-chip (SoC), various kinds of clock signals, selectively driven by different frequency-dependent sources and/or dividers (DIVs), are usually centralized in one or more clock generation modules, where clock gating cells (CGCs), multiplexers (MUXes) and DIVs are used to create the clocks required by different functional operations in an SoC. These modules will introduce uncommon and longer timing paths for clock propagations and further make the clock tree synthesis (CTS) process become more challenging due to the on-chip-variation (OCV) effects. In addition, high volume of switching activities in the increased number of clock logic cells will consume more power. In this article, a novel design platform, merging and replacing of multiple multiplexers and dividers (MRMMD), is developed to intelligently identify those suspicious clock architectures and resynthesize them into a power-and-area effective and less complicated clock structure. Using our resynthesis platform, not only the number of clock-related timing paths and their corresponding logic levels can be reduced, but also the corresponding analysis and implementations of clock skew minimizations during CTS become much easier. The experimental results implemented in TSMC 55- and 28-nm process nodes on optimizing some industrial clock architectures showed that significant reductions of area, power, latency, skew and clock path, logic level, OCV impact, total wire length, and implementation runtime are achieved using our MRMMD platform.