What is Channel Operating Margin (COM)? You might be more familiar with Channel Operating Margin (COM) as it relates to IEEE 802.3 and OIF-CEI standards that use Phase-Amplitude-Modulation. For example, PAM-4 encodes four symbols per unit interval (UI), whereas NRZ modulation encodes one symbol per UI. A key advantage of PAM is that deployed hardware and existing PCB technology bins can achieve higher data-throughput rates by enhancing the modulation capability of PHY designs in silicon. ...