PAM3: History, Algorithm, and Performance Comparison to NRZ and PAM4

The origin and evolution of Three-level Pulse Amplitude Modulation (PAM3) are introduced. Two PAM3 variant encoding schemes (3-bit-to-2-trit (3B2T) and 11-bit-to-7-trit (11B7T)) are described, along with the trit test sequence for PAM3. The high-speed transmission performance of PAM3 is investigated under the influences of five major channel impairments, with NRZ and PAM4 as comparisons. The work reveals that PAM3 has a certain performance advantage over NRZ and PAM4 in terms of reflection coefficient, insertion loss, and mode conversion, while being relatively more sensitive to crosstalk and noise.