Architectures and Synthesis Algorithms for Power-Efficient Bus Interfaces

In this paper we present algorithms for the synthesis of encoding and decoding interface logic that minimizes the average number of transitions on heavily-loaded global bus lines at no cost in communication throughput (i.e., one word is transmitted at each cycle). The distinguishing feature of our approach is that it does not rely on designer's intuition, but it automatically constructs low-transition activity codes and hardware implementation of encoders and decoders, given information on word-level statistics. We propose an accurate method that is applicable to low-width buses, as well as approximate methods that scale well with bus width. Furthermore, we introduce an adaptive architecture that automatically adjusts encoding to reduce transition activity on buses whose word-level statistics are not known a priori. Experimental results demonstrate that our approaches out-perform specialized low-power encoding schemes presented in the past