Theoretical bounds for switching activity analysis in finite-state machines

The objective of this paper is to provide lower and upper bounds for the switching activity on the state lines in Finite State Machines (FSMs). Using a Markov chain model for the behavior of the states of the FSM we derive theoretical bounds for the average Hamming distance on the state lines which are valid irrespective of the state encoding used in the final implementation. Such lower and upper bounds, in addition to providing a target for any state assignment algorithm, can also be used as parameters in a high-level model of power and thus provide an early indication about the performance limits of the target FSM. Experimental results obtained for the mcnc´91 benchmark suite show that our bounds are tighter than the bounds reported previously by other researchers and can be effectively used in a high-level power estimation framework.