This paper presents a new asynchronous data-transfer scheme based on two-color two-rail complementary coding, which is suitable for a multiple-valued current-mode VLSI circuit. Two kinds of R-valued two-rail complementary signals, called ' two-color two-rail codes, ' which represent 'data values, ' are used in odd and even phases, respectively. The sum of R-valued two-rail complementary values in an odd phase is a constant (R-1), while the sum of R-valued two-rail complementary values in an even phase is also a constant 3 (R-1). The difference of these constant values in the two-color coding makes it easy to detect a data-arrival state from a data-transition state without spacers. Moreover, basic components to realize the above asynchronous VLSI system, a signal-state detector to detect a data-arrival state, and a two-color code generator to produce two-color two-rail signals can be easily designed by a multiple-valued current-mode circuit technology based on dual-rail differential logic. Finally, the advantage of the proposed asynchronous multiple-valued VLSI circuit is demonstrated in comparison with the corresponding binary implementation.
