Resynthesis and retiming of synchronous sequential circuits

Retiming is a technique used in synchronous sequential circuits to move the registers across the circuit in order to minimize the cycle time or the number of registers used. Peripheral retiming is extended retiming in which all registers are moved (if possible) to the peripheral edges, where combinational logic optimization techniques can be used. A generalization of this method is proposed. It consists in moving the maximum number of registers to the peripheral edges. This approach may then also be applied to all sequential circuits for which the usual peripheral retiming concept does not hold. The authors' model of the circuit is a bipartite graph, and it is proved that the resynthesizing problem is equivalent to a linear optimization problem in this graph. A new algorithm for the optimization of sequential circuits is proposed.<>