US Patent 7142612 Method and apparatus for multi-level signaling

A system transmits data on a multi-conductor signal path, which produces a current flow based on the value of the data transmitted. The system reduces changes in current flow between successive data transmissions by encoding data values represented by sets of N bits to produce corresponding sets of M symbols. Each set of M symbols represents multiple bits and each set of M symbols is selected to produce a current flow within a predetermined range of current flows. The sets of M symbols are transmitted across the multi-conductor signal path.