Fig.1: NRZ signal (top) and eye diagram (bottom). Pulse amplitude modulation builds upon this concept by encoding data across multiple voltage levels. PAM4 uses four levels. A PAM4 signal can appear ...

Figure 1 PAM4 doubles the number of bits in serial data transmissions by increasing the number of levels of pulse-amplitude modulation, but does so at the cost of noise susceptibility. If we look at ...