Encoding techniques for energy-efficient and reliable communication in VLSI circuits.

摘要

System-on-chip (SoC) is evolving as a result of increasing number of devices that can be integrated on a single chip. As an adaptation to enormous SoC design complexity, design flow is shifting toward interconnecting different pre-designed macro-cells or subsystems with application specific interconnects and buses. Interconnection of these modules will be a major challenge for realization of these complex and highly integrated systems. In this dissertation, we will address the power consumption and reliability issues that arise in the design process and propose encoding and decoding solutions that help overcome these bottlenecks.; Several encoding techniques are proposed that can effectively reduce switching activity over instruction and data address buses. This is achieved by exploiting the spatial locality of the traces that flow over these buses. These techniques are all designed to accommodate for the specific limitations of encoding over on-chip and off-chip buses such as tight delay constraints and power and area considerations.; Another set of encoding techniques named Sector-based encoding techniques, are proposed that are specifically very strong in exploiting spatio-temporal locality of various kind of traces. The fixed version is very suitable for hardware implementations (e.g. for low power applications) whereas the dynamic version is better suited for software implementations (e.g. for data compaction).; An instruction-set-aware memory is proposed that is capable of predicting the addresses to some extent. This will lead to a reduction of traffic over the memory bus that can be targeted for power reduction or performance improvement.; An Energy-efficient, reliable channel for on-chip communication is proposed. This includes a pattern-sensitive encoding scheme that selects the optimum encoding technique based on the sensitivity of patterns. Besides, various levels of reliability (encoding techniques) are selected in such a way that consistency between encoder and decoder is guaranteed with zero communication overhead.; Finally, the problem of hot-carrier device degradation for bus drivers is tackled from an encoding point of view. The problem is systematically solved by, first, characterizing of the data that appears on the bus, and then finding combinational and/or sequential encoding functions that efficiently solve the problem.