Temperature-aware clock tree synthesis considering spatiotemporal hot spot correlations

Abstract

Temperature variation in microprocessors is a workload dependent problem. In such a design, the clock skew should be minimized with respect to temperature variation. Existing work has studied clock tree embedding perturbation considering time variant temperature variation. There is no existing method that can reduce skew variation. This paper develops an efficient yet effective simultaneous hotspot avoid embedding and thermal aware routing (TMST) method, where hotspot embedding avoid tree topology located in area with high temperature possibility and thermal aware routing reduce skew in tree path with more smooth temperature area. With a thermally tolerable tree structure, our method can reduce not only delay skew but also skew variation (skew violation range). Compared with existing temperature-aware clock tree method, our TMST solution reduces skew variation by 2X compared with the greedy-DME (GDME) method of Edahiro and existing thermal aware clock synthesis TACO and PECO. With the scale from 100 down to 1 temperature maps, our TMST also guarantees the smallest wire length overflow. TMST reduces the worst case skew up to 4X than PECO and 5X than TACO.