Adaptive Bus Encoding for Transition Reduction on Off-Chip Buses With Dynamically Varying Switching Characteristics

Abstract

This paper presents an adaptive encoding framework for the reduction of transition activity in high-capacitance off-chip data buses, since power dissipation associated with those buses can be significant for high-speed communication. The technique relies on the observation of data characteristics over fixed window sizes and formation of cluster with bit lines having highly correlated switching patterns. The proposed method utilizes redundancy in space and time to prevent loss of information while retrieving data. We present analytical and experimental analyses, which demonstrate the activity reduction of our encoding scheme for various data. The extra power cost due to the encoder and decoder circuitry along with redundancy is offset due to reduced number of off-chip transitions.