System-level characterization of modal signaling for high-density off-chip interconnects

In high-speed chip-to-chip single-ended signaling links, far-end crosstalk presents one of the dominant noise sources, limiting the link performance. Diagonalizing the channel using modal decomposition has been proposed to mitigate the crosstalk. However, a practical circuit implementation of such a transceiver system will unavoidably deviate from the ideal (crosstalk-free) eigenvalue decomposition. In this paper, the impact of modal encoder/decoder coefficient quantization, random common and uncorrelated noise on signal integrity is analyzed in terms of system-level performance metrics, SNR and BER. Also discussed is the optimal selection of decoder coefficients with respect to the input-referred noise at the receiver.