Switching codes for delta-I noise reduction

In this paper, we address the off-chip driver delta-I or switching noise problem. We propose a novel approach based on switching codes to reduce this noise. These codes are designed to lower the number of drivers which switch in any given system cycle. A formal theoretic framework for switching codes is developed which provides an upper bound on the number of switching drivers as a function of bit width of the data bus and number of redundant switch bits. Switching codes with error detecting and error correcting capabilities are also presented. Switching codes also reduce the average switching activity and power consumed by the off-chip drivers.