Implementation of a thermal management unit for canceling temperature-dependent clock skew variations

Thermal gradients across the die are becoming increasingly prominent as we scale further down into the sub-nanometer regime. While temperature was never a primary concern, its non-negligible impact on delay and reliability is getting significant attention lately. One of the principal factors affecting designs today is timing criticality, which, in today’s technologies is mostly determined by wire delays. Clocks, which are the backbone of the interconnect network, are extremely prone to temperature dependent delay variations and need to be designed with extreme care so as to meet accurate timing constraints. Their skew has to be minimized in order to guarantee functionality, albeit in the presence of these process variations. Temperature, on the other hand, is dynamic in nature and its effects hence need run-time monitoring and management. One of the most efficient ways to manage temperature dependent skew is through the use of buffers with dynamically tunable delays. The use of such buffers in the clock distribution network allows modulating the delay on selected branches of the clock network based on a thermal profile, so as to keep the skew within acceptable bounds. A runtime scheme obviously requires an on-line management unit. Our work predominantly focuses on the implementation of one such unit, while studying its impact on design parameters such as area, wire-length and power. Results show negligible a impact (0.67% in area, 0.62% in wire-length, 0.33% in power, and 0.37% in via-number) on the design. r 2007 Elsevier B.V. All rights reserved.