Joint equalization and coding for on-chip bus communication

In this paper we propose using joint equalization and coding to improve on-chip communication speeds by signaling at rates beyond the rate governed by RC delay of the interconnect. Operating beyond the RC limit introduces intersymbol interference (ISI). We mitigate the effects of ISI by employing equalization. The proposed equalizer employs a variable threshold inverter whose switching threshold is modified as a function of past output of the bus. We demonstrate even higher speed-ups by combining equalization with crosstalk avoidance coding. Specifically, simulation results for a 10-mm 32-bit bus in 0.13-μm CMOS technology show that 1.28× speed-up is achievable by equalization alone and 2.30× speed-up is achievable by joint equalization and coding.