Review of the basic line coding techniques for high-speed electrical interconnects

A review of baseband modulation techniques intended for use in high-speed electrical interconnects is presented. A general framework is developed and used to compare the performance of traditional baseband formats and partial response coding. A special focus is placed on spectral characteristics suitable for the high-speed electrical interconnects. For that reason multiple classes of partial response signaling are evaluated to shape power spectral density. This unified treatment is extended to multilevel modulation formats. A comparison between symbolby- symbol and maximum-likelihood detection schemes is made with a conclusion that the latter can efficiently complement or replace forward error correction in partial response systems. A complexity analysis shows that significant simplifications can be done in the detection process without drastically impacting the error ratio.