During synthesis of power gated finite state machine (FSM) power can be reduced by reducing switching activity of the implemented circuit. Power gating can be applied to turn OFF the inactive sub-machine which is obtained after partitioning the FSM by gating the supply voltage. During transition from the states of one sub-machine to other sub-machine, wakeup time is required to turn OFF the current sub-machine and turn ON other. Wakeup time affects the partitioning of FSMs for its power gated implementation as both the sub-machines are ON during this time. In this paper, we have calculated this wakeup time to find the boundary depth. Variation of wakeup time as a function of size of sleep transistor and sub-machine has also been studied. Power model has been developed for the power-gated design of FSM. Here, we present a Genetic Algorithm (GA) based solution of the problem of both partitioning and encoding of power gated FSM for reduced power consumption Experimental results show that more than 55% power can be saved in this approach.

1. G. Venkataraman, S. M. Reddy, I. Pomeranz, "GALLOP: Genetic Algorithm based Low Power FSM Synthesis by Simultaneous Partitioning and State Assignment", Proceedings of 16th IEEE conf. on VLSI design, pp. 533-538, (2003).
2. B. Liu, Y. Cai, Q. Zhou, J. Bian, X. Hong, "FSM decomposition for power gating design automation in sequential circuits", Proceedings of the ASICON, pp. 862-865, (2005).
3. S. N. Pradhan, M. Tilak Kumar and S. Chattopadhyay, "Low power FSM synthesis using Power-gating", Integration, the VLSI Journal, Vol. 44, No. 3, pp. 175-184, (2011).
4. T. Villa, A. S. Vincentell, "NOVA: State Assignment of Finite State Machines for Optimal Two-Level Logic Implementation", IEEE transactions on CAD. VOL. 9 NO. 9. pp. 905-924, Sep. (1990).
5. A. T. Freitas, and A. L. Oliveira, "Implicit resolution of the Chapman-Kolmogorov equations for sequential circuits: an application in power estimation", Proceedings of the Design, Automation and Test in Europe Conference and Exhibition, pp. 764-769, (2003).
6. D. E Goldberg and J. H. Hollend, "Genetic Algorithms in Search, Optimization and Machine Learning", Addison-Wesley, (1988).
7. J. Seomun, I. Shin and Y. Shin ,"Synthesis and implementation of active mode power gating circuits", Proceedings of Design Automation Conference (DAC), 47th ACM/IEEE (2010).
8. S. Chattopadhyay and P. N Reddy, Finite state machine state assignment targeting low power consumption, IEE proc. -Comput. Digit. Tech. , Vol. 151, No. 1, January 2004.

Finite State Machine Partitioning Power Gating Wakeup Time Boundary Depth Power Model Low Power