A vectorless estimation of maximum instantaneous current for sequential circuits

Both the IR drop and EM problems require accurate analysis of maximum instantaneous current (MIC) on the power supply bus. We propose a vectorless approach to deriving a tight upper bound on MIC. We first characterize different types of signal correlation which may cause the MIC estimation to lose accuracy. We next propose theorems to identify gates which switch mutually exclusively, taking into account correlation across sequential elements (flip-flops). Note that previous research of this topic addressed on combinational circuits only. After obtaining the information of mutually exclusive switching, we then apply a graph algorithm to obtain an upper bound on MIC. In average, our results on sequential benchmarks are 212% tighter than those from iMax and 129% tighter than those from PIE based on H. Kriplani et al. (1995).