Design of asynchronous logic with unconstrained input variation

In asynchronous circuits operating in the fundamental mode, a restriction is imposed on the input variables to the circuit requiring that only one variable may change state at any time. A design method is described which uses an asynchronous delay circuit to generate minimum-distance codes from the primary inputs, which are then used as inputs to a modified version of the basic circuit; using these techniques, input changes of any description may be tolerated. Design equations are presented for a 2-input circuit allowing up to 40ns delay between `simultaneously¿ changing inputs.