Accurate and Efficient Technique to Calculate Sensitivities of' Power to Primary Inputs

Recently, several power estimation techniques have been proposed. Some of them can be used to accurately estimate power dissipation provided that the exact signal probability probability of a signal being logic ONE) and signal activity (probability of signal switching) of primary inputs are known. In general, very accurate specification of primary input signal probability and activity may not be available. This in turn may result in uncertainties in average power estimation. In this paper we present a novel and efficient technique t o estimate the sensitivity of average power dissipation t o input signals using a symbolic estimation technique. Results for benchmark ciircuits show that power sensitivities can vary widely for different primary inputs of a circuit. Hence, in order to accurately estimate average power dissipation, the sensitive inputs of a circuit have t o be specified accurately. We have also developed a Monte-Carlo based technique to estimate power sensitivity which also acts as a figure of merit for the symbolic technique.