Elastic Timing Scheme for Energy-Efficient and Robust Performance

Abstract

In nanometer regime, IC designers are struggling between significant variation effects and tight power constraints. The conventional approach - using timing safety margin, consumes power continuously to guard against low probability timing variations. Such power inefficiency is largely eliminated in the Razor technology which detects and corrects variation induced timing errors at runtime. However, the error correction scheme of Razor causes pipeline stalling/flushing and therefore is not preferred in real-time systems or sequential circuits with feedback loops. We propose an elastic timing scheme which can correct timing errors without stalling/flushing pipeline. This is achieved by dynamically boosting circuit speed when timing error occurs. A dynamic clock skew shifting technique is suggested to reduce the boosting cost. An optimization algorithm is also provided to minimize the cost overhead. Compared to conventional safety margin based approach, the elastic timing scheme can reduce power dissipation by 20 % - 27 % on ISCAS89 sequential circuits while retaining similar variation tolerance. After optimization, the boosting is needed for only a small portion of entire circuit. As a result, the area overhead is usually less than 5 %.