Two-Dimensional Symbol Mapping for Evaluating Multi-Valued Data Transmission Quality

Multi-valued data transmission using four-level pulse amplitude modulation (PAM-4) coding is a promising method to alleviate the bandwidth limitation of interconnects. This study proposes a novel eye-opening monitoring technique based on the characteristics of PAM-4 symbol transition to evaluate the received signal quality for the adaptive coefficient settings of a PAM-4 equalizer. The two-dimensional (2D) symbol transition mapping enables visualization of the degree of intersymbol interference (ISI). The simulation and experimental results demonstrate that the 2D symbol mapping can evaluate the PAM-4 data transmission quality degraded by the ISI and can also visualize the effect of equalization. The future research objectives of this study include the implementation of the proposed technique to the eye-opening monitor to achieve greater precision in the adjustment of equalizers.