Variation-Aware Clock Network Design Methodology for Ultralow Voltage (ULV) Circuits

This paper presents a design methodology for robust and low-energy clock networks for ultralow voltage (ULV) circuits. We show that both clock slew and skew play important roles in achieving high maximum operating frequency (F_max) and low clock energy in ULV circuits. In addition, clock networks in ULV circuits are highly sensitive to process variations. We propose a variation-aware methodology that controls both clock skew and slew to maximize F_max and minimize clock power. In addition, we implement dynamic programming (DP)-based ULV clock routing and buffering methods (deferred merging and embedding) for deterministic and statistical conditions. Experimental results show that our clock network design method achieves lower energy (more than 20% savings) at comparable or even higher F_max compared with the existing methods.