Delay insensitive system-on-chip interconnect using 1-of-4 data encoding

The demands of System-on-Chip (SoC) interconnect increasingly cannot be satisfied through the use of a shared bus. A common alternative, using unidirectional, point-to-point connections and multiplexers, results in much greater area requirements and still suffers from some of the same problems. This paper introduces a delay-insensitive, asynchronous approach to interconnect over long paths using 1-of-4 encoded channels switched through multiplexers. A reimplementation of the MARBLE SoC bus (as used in the AMULET3H chip) using this technique shows that it can provide a higher throughput than the simpler tristate bus while using a narrower datapath.