Feedback in asynchronous sequential circuits

In this paper we examine the problem of feedback in asynchronous sequential circuits. A procedure is presented whereby any normal fundamental mode flow table can be realized as a fundamental mode circuit with feedback index ⌈log2maxi(Si)⌉ where Si is the number of stable states in column i of the flow table and it is shown that this result is optimal. The realization requires no inverters (assuming double-rail inputs), and is therefore a minimal transistor realization if diode logic is used.