Improving the efficiency of Monte Carlo power estimation

In this paper, we propose two efficient statistical sampling techniques for estimating the total power consumption of large hierarchical circuits. We first show that, due to the characteristic of sampling efficiency in Monte Carlo simulation, granularity of samples is an important issue in achieving high overall efficiency, The proposed techniques perform sampling both tem porally (across different clock cycles) and spatially (across different mod ules) so that smaller sample granularity can be achieved while maintaining the normality of samples. The first proposed technique, which is referred t o as the module-based approach, samples each module independently when form ing a power sample. The second technique, which is referred to as the clust er-based approach, lumps the modules of a hierarchical circuit into a numbe r of clusters on which sampling is then performed. Both techniques adapt st ratification to further improve the efficiency, Experimental results show t hat these techniques provide a reduction of 2-3 x in simulation run time co mpared to existing Monte-Carlo simulation techniques.