The Chemical Connection: Onshoring PCB Production—Daunting but Certainly Possible
Marcy’s Musings: The Legislative Outlook—Helping or Hurting?
It’s Only Common Sense: The Phone Is Still Mightier Than the Keyboard
Paving the Way for 400Gb Ethernet and 5G
June 26, 2018 | Chang Fei Yee, Keysight TechnologiesEstimated reading time: 1 minute
This article briefly introduces the 4-level pulse amplitude modulation (PAM-4) and its application in 400 Gigabit Ethernet (400GbE), to support the booming data traffic volume in conjunction with the deployment of 5G mobile communications. Furthermore, this article also highlights the essential pre-layout effort from signal integrity perspective for physical (PHY) link design on a PCB, including material selection, transmission line design and channel simulation to support 56Gbps data rate that paves the way for seamless communication in 400GbE.
I. Introduction
400GbE is a new wired communication standard to accommodate the booming data traffic volume with the implementation of 5G mobile communications. In the implementation of 400GbE communication, electrical interface with 4-level pulse amplitude modulation (PAM-4) signaling over 8 lanes is adopted. The communication of eight lanes at 56Gbps (i.e., 28GBaud) per lane enables the total bandwidth of 400Gbps over the Ethernet. The electrical specifications of 400GbE with PAM-4 signaling are defined in IEEE 802.3bs.
PAM-4 has 4 digital amplitude levels, as shown in Figure 1. It has an advantage over non-return-to-zero (NRZ) signals because each level or symbol in PAM-4 contains two information bits providing twice as much data throughput for the same baud rate. For instance, 28GBaud is equivalent to 56Gbps in PAM-4 and 28Gbps in NRZ respectively.
II. Essential pre-layout effort from signal integrity perspective
According to guidelines, a PAM-4 channel with trace length up to 8 inches on a PCB shall have insertion loss less than 10dB at 14GHz (i.e., Nyquist frequency of 28GBaud) and 20dB at 28GHz (i.e., 2nd harmonic of 28GBaud) respectively to achieve seamless data communication between the transceivers.
To read this entire article, which appeared in the May 2018 issue of Design007 Magazine, click here.
Share on:
Testimonial
"Your magazines are a great platform for people to exchange knowledge. Thank you for the work that you do."
Simon Khesin - Schmoll MaschinenSuggested Items
Peters, Starteam, and Würth Elektronik Team Up For Digital Coating Technology
10/23/2025 | PetersUnder this heading, the PCB manufacturers Starteam and Würth Elektronik, along with Peters as inkjet coating supplier, have taken the initiative and worked together for months in trusting and target-oriented cooperation, to promote this innovative digital coating technology for solder resists and establish it on the market.
AI Triggers Next Paradigm Shift in PDN
10/23/2025 | Istvan Novak, SamtecArtificial intelligence (AI), together with machine learning (ML), is creating an unprecedented surge of computing and networking infrastructure needs. This, in turn, has dramatically increased the power consumption of computing and networking chips.
SEMICON Japan 2025 to Spotlight Sustainability in AI and Semiconductor Innovation
10/22/2025 | SEMISEMICON Japan 2025, the largest gathering of leaders from the microelectronics manufacturing supply chain in Japan, will bring together more than 1,200 exhibitors showcasing semiconductor solutions from December 17-19 at Tokyo Big Sight.
Zuken Announces ZIW Americas 2026 in Dallas
10/21/2025 | ZukenZuken USA, Inc., a global leader in electrical and electronic design automation, announced Zuken Innovation World (ZIW) Americas 2026, the company’s premier global conference dedicated to advancing the future of electrical and electronic product design. ZIW 2026 will be held June 9-11 in Dallas, Texas.
Keysight Completes Acquisition of Synopsys’ Optical Solutions Group and Ansys’ PowerArtist
10/17/2025 | Keysight Technologies, Inc.Keysight Technologies, Inc., announced the completion of its acquisitions of the Optical Solutions Group from Synopsys, Inc., and PowerArtist from Ansys, Inc.