Energy-Per-Cycle Estimation at RTL †

Abstract – We present a novel macromodeling technique for estimating the energy dissipated in a logic circuit for every input vector pair (we call this the energy-per-cycle). The macromodel is based on classifying the input vector pairs on the basis of their Hamming distances and using a different equation-based macromodel for every Hamming distance. The variables of our macromodel are the zero-delay transition counts at three logic levels inside the circuit. We present an automatic characterization process by which such macromodels can be constructed. This energy-per-cycle macromodel provides a transient energy waveform, and can also be used to estimate the moving average energy over any time window. This approach has been implemented and models have been built and tested for many circuits. The average error observed in estimating the energy-per-cycle is under 20%. The model can also be used to measure the long-term average power, with an observed error of under 10% on average. 1