Register-transfer level estimation techniques for switching activity and power consumption

Abstract

We present techniques for estimating switching activity and power consumption in register-transfer level (RTL) circuits. Previous work on this topic has ignored the presence of glitching activity at various data path and control signals, which can lead to significant underestimation of switching activity. For data path blocks that operate on word-level data, we construct piecewise linear models that capture the variation of output glitching activity and power consumption with various word-level parameters like mean, standard deviation, spatial and temporal correlations, and glitching activity at the block's inputs. For RTL blocks that operate on data that need not have an associated word-level value, we present accurate bit-level modeling techniques for glitching activity as well as power consumption. This allows us to perform accurate power estimation for control-flow intensive circuits, where most of the power consumed is dissipated in non-arithmetic components like multiplexers, registers, vector logic operators, etc. Since the final implementation of the controller is not available during high-level design iterations, we develop techniques that estimate glitching activity at control signals using control expressions and partial delay information. Experiments on example RTL designs resulted in power estimates that were within 7% of those produced by an inhouse power analysis tool on the final gate-level implementation.