Skew Bounded Buffer Tree Resynthesis For Clock Power Optimization

With aggressive technology scaling in nanometer regime, a significant fraction of dynamic power is consumed in the clock network due to its high switching activity. Clock networks are typically synthesized and routed to optimize for zero clock skew. However, clock skew optimization is often accompanied with routing overhead which increases the clock net capacitance thereby consuming more power. In this paper, we propose a skew bounded buffer tree resynthesis algorithm to optimize clock net capacitance after the clock network has been synthesized and routed. Our algorithm restricts the skew of the designs within a specified margin from its original skew, and does not introduce any additional Design Rule Check (DRC) violation. Experimental results on industrial designs, with clock networks synthesized and routed by an industrial tool, have demonstrated that our approach can achieve an average reduction of 5.6% and 3.5% in clock net capacitance and clock dynamic power respectively with a marginal overhead in the clock skew.