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In this paper, three effective design techniques are presented to effectively reduce the clock power consumption and slew of the 3D clock distribution network: (1) controlling the bound of through-silicon-vias (TSVs) used in between adjacent dies, (2) controlling the maximum load capacitance of the clock buffer, (3) adjusting the clock source location in the 3D stack. We discuss how these design factors affect the overall wirelength, clock power, slew, skew, and routing congestion in the practical 3D clock network design. SPICE simulation indicates that: (1) a 3D clock tree with multiple TSVs achieves up to 31% power saving, 52% wirelength saving and better slew control as compared with the single-TSV case; (2) by placing the clock source on the middle die in the 3D stack, an additional 7.7% power savings, 9.2% wirelength savings, and 33% TSV savings are obtained compared with the clock source on the topmost die. This work aims at helping designers construct reliable low-power and low-slew 3D clock network by making the right decisions on TSV usage, clock buffer insertion, and clock source placement.
Date of Conference: 18-21 Jan. 2010