Realization of Asynchronous Sequential Circuits Without Inserted Delay Elements

Abstract—In an earlier paper, Unger showed that any normal mode flow table can be realized by an asynchronous sequential circuit without inserted delays in the feedback paths if and only if the flow table contains no essential hazards. No restrictions were placed on the relative magnitudes of line and gate delays. In this paper, we show that if the line delays are less than the minimum gate delay in the circuit, any normal mode sequential function can be realized without inserted delays. It is also shown that a weaker line delay assumption is sufficient. Two procedures for realizing asynchronous sequential circuits without inserted delays are presented.