Asynchronous multiple-valued VLSI system based on dual-rail current-mode differential logic

This paper presents a new asynchronous data-transfer in a multi-valued current-mode VLSI circuit based on dual-rail differential logic. In the proposed 2-phase multiple-valued asynchronous communication scheme, R-valued dual-rail complementary signals are used to represent a "data value" while the "spacer" is represented as (0, 0). The sum of R-valued dual-rail complementary values is a constant (R-1) which makes it easy to distinguish a data-arrival state from a data-transition state. This scheme can be extended to any multiple-valued data representation in asynchronous communication. New basic components, a signal-state detector to detect a data-arrival state, and a current-controlled threshold detector to produce dual-rail spacer signals (0,0) are also proposed to realize a compact asynchronous control circuit. It is demonstrated that the overhead for the proposed asynchronous circuit is very small compared with the conventional synchronous multiple-valued current-mode logic approach.