Energy efficiency of micropipelines under wide dynamic supply voltages

The contradictions among high performance, low power and unpredictable energy supply motivate a large part of current mobile and embedded system design research especially on systems that can work under a wide range of voltages. Concurrency has been used to improve performance and/or efficiency, but has not been properly studied with widely variable supply voltages. In this paper, a self-timed micropipeline is designed to investigate system behaviour under a wide range of voltages, focusing on asynchrony and the relationship between the degree of concurrency and all important performance metrics including the amount of computation. Results suggest that above threshold, the amount of computation per given amount of energy is practically insensitive to the degree of concurrency, but below threshold the dependency on the degree of concurrency goes up significantly. This indicates that probably the best architectures for energy efficiency are asynchronous data-flow ones and those operating in sub-threshold.