Comparative Analysis of Conventional and Statistical Design Techniques

We explore the power benefits of changing a microprocessor path histogram through circuit sizing based on statistical timing analysis and optimization (STAO) versus a deterministic timing approach that uses statistical design to establish a global guardband followed by conventional optimization (SDGG). Using an analytical modeling approach, we quantify the differences in total power between the two approaches while maintaining an equivalent performance distribution. For a relative1sigma random WID stage delay variation of 5% and representative microprocessor critical paths, the analysis indicates that the STAO approach enables ~2% power reduction over the SDGG approach. To achieve a 4% and 6% power reduction through the STAO approach, the process variation needs to increase by a factor of 2x and 4x, respectively.