Adaptive and Reliable Clock Distribution Design for 3-D Integrated Circuits

In this paper, we present novel techniques to handle the complexity and challenges in clock distribution for 3-D integrated circuit. First, we propose a novel active deskew technique to adaptively mitigate the cross-tier variations and the 3-D wiring asymmetry. The new deskew technique neither relies on an accurate through-silicon-vias model nor an accurate reference clock distribution. Second, we design a phase-mixer-based tunable-delay-buffer (TDB), which can be linearly tuned in 360° and tolerant to process-voltage-termperature (PVT) variations. Third, based on the new deskew technique and TDB design, we propose an efficient clock distribution network topology, which can be realized without a need of balanced H-tree. Moreover, a thermal profile-based optimization flow is developed to further improve the power efficiency and reduce design overhead. A case study shows that the proposed techniques are able to largely improve the clock skews. The optimization flow is capable of reducing the design cost to achieve a better tradeoff of the skew performance and the design overhead.