Before answering "Why SerDes signaling tends to PAM coded signals", please answer two questions first: 1. What is the difference between NRZ, PAM-3 and PAM-4? 2. What is the application of PAM encoding? 1. What is the difference between NRZ, PAM-3 and PAM-4? The following three pictures clearly show the differences between them: Figure 1: NRZ, waveform, eye diagram Figure 2: PAM-3, waveform, eye diagram Figure 3: PAM-4, waveform, eye diagram 2. What is the application of PAM encoding? When the signal is converted from parallel to serial in order to achieve high-speed connection, the timing challenge is eliminated from the PCB, and the chip design bears the responsibility of clock and data recovery. With 32 Gbps serial links approaching PCI Express 5.0, it is difficult for us to double the speed of next-generation interfaces without innovation. OIF-CEI is currently specifying a 56 Gbps interface with 2-bit intervals per unit. This multi-level signaling is called PAM-4. Multi-level signaling is also used in the field of automotive Ethernet. In this application, 100 Mbps signaling is much slower than the OIF-CEI interface, but by including one more bit in each conversion, the rise time of the signal can be slower and produce less EMI. The car is a very important safety consideration. The automotive Ethernet standard, 100-Base T1, uses PAM-3 signaling to transmit 1½ bits of data per unit interval; 1000-Base T1, which can run at 1Gbps speed, is in the adoption stage. Whether you are considering OIF-CEI or automotive Ethernet, there is no doubt that you need to verify that the PAM-encoded signal complies with the standard before bringing the prototype to the laboratory. Cadence Sigrity™ signal integrity technology currently supports PAM-3 and PAM-4 signaling. You can simulate and analyze the behavior of the signal from the transceiver to the transceiver. We have prepared a short demonstration video to help you better understand the PAM signal and analysis technology through the Allegro®Sigrity™System Serial Link Analysis Option tool, which will help you successfully design and analyze the PAM coded serial link interface : 1500 Puffs Vape,E-Cigarette 1500 Puffs,Disposable Vape Pen E-Cigarette,All-In-One Electronic Cigarette Guangzhou Yunge Tianhong Electronic Technology Co., Ltd , https://www.e-cigaretteyfactory.com
