A note on the relationship between signal probability and switching activity

In current probability calculation algorithms for power estimation, switching activity E/sub SW/ of a node is calculated from its signal probability p by the following simple relation: E/sub SW/=2p(1-p). It is generally understood that this simple relationship holds under the temporal independence assumption for the node. This paper however shows that the above equation also gives the expected value of the transition activity in any sequence that satisfies the given signal probability (averaged over all such sequences). Therefore, this equation can be used to calculate the switching activity under more general conditions than previously thought.