To date, the probabilistic approach is in widespread use to
analyze the power dissipation of digital circuits. The goal of
the present work is twofold. First, to present a method in
providing an evaluation package of signals' probabilities and
transition densities that can be applied at different
specification levels with more or less accuracy. A first order
clue at the specification level may help synthesis tools in
lowering power dissipation early in the design process. Second,
to show how to deal with the well-known correlation problem
using a symbolic simulation technique. Only one pass is
required to compute a set of independent inputs for each signal
in the circuit. At different stages, the algorithms take
advantage out of the Binary Decision Diagram (BDD) concept.