High Swing Pulse-Amplitude Modulation of Transmission Line Links for On-Chip Communication

With ever increasing core count of chip-multiprocessors (CMPs), the network-on-chip (NoC) fabric continues to be an important component for performance and energy. We propose the use of high voltage swing serial links as the backbone NoC. We designed transmitter drivers to deliver a high output swing and enable high speed Pulse-Amplitude Modulation (PAM-4 and PAM-8) transmissions. We show that with careful circuit-level transceiver design, coupled with system level architectural utilization of such links, it is possible to drive up to 8 cm of on-chip transmission line at diverse adaptive modulations. Using such a design, experimental analysis shows an average of 1.4x performance improvement over baseline. The overall energy-delay product improvement is 1.75x.