Encoding-based minimization of inductive cross-talk for off-chip data transmission

Inductive cross-talk within IC packaging is becoming a significant bottleneck in high-speed inter-chip communication. The parasitic inductance within IC packaging causes bounce on the power supply pins in addition to glitches and rise-time degradation on the signal pins. Until recently, the parasitic inductance problem was addressed by aggressive package design. We present a technique to encode the off-chip data transmission to limit bounce on the supplies and reduce inductive signal coupling due to transitions on neighboring signal lines. Both these performance limiting factors are modeled in a common mathematical framework. Our experimental results show that the proposed encoding based techniques result in reduced supply bounce and signal degradation due to inductive cross-talk, closely matching the theoretical predictions. We demonstrate that the overall bandwidth of a bus actually increases by 85% using our technique, even after accounting for the encoding overhead. The asymptotic bus size overhead is between 30% and 50%, depending on how stringent the user-specified inductive cross-talk parameters are.