Signal Integrity Webinar Series
Title: Test, Measurement, and Analysis of PAM4 Signals
Date: August 22, 2017
Time: 9am PT/ 12pm ET
Sponsored by: Anritsu Co. and Samtec
Presented by: Ransom Stephens, PhD
At data rates above 25 Gb/s, signal impairments reach the point that we have to adopt a whole new approach. At these rates the convenient, logic-emulating NRZ signal modulation scheme fails in most systems. While many factors go into signal impairment—loss, frequency response, jitter, noise, and crosstalk—the ultimate failure of NRZ can be traced to the bandwidth limit of the channel. By encoding two bits per symbol, PAM4 signals use half the bandwidth of NRZ. The cost is increased complexity and at least 9 dB in signal to noise ratio. Our seminar begins with an introduction to the nuances of PAM4 signaling and techniques for evaluating if PAM4 is necessary for a given system. We then dive into test techniques for evaluating PAM4 signals and the performance of PAM4 receivers emphasizing what can be leveraged from NRZ and what is new for PAM4.
Ransom Stephens, Ph.D. helps engineers advance to the highest data rates by teaching the concepts engineers need to design better systems, better serdes, and better ways to find problems and come up with solutions. Ransom started in basic research at labs in the US and Europe specializing in digging weak signals out of strong backgrounds. He brought those skills to high speed electronics in 1999 and invented new techniques for signal and noise analysis. Since 2005, when he started Ransom’s Notes, his seminars have helped thousands of EEs understand key nuances of their work. Ransom was named the 2017 Jim Williams ACE Contributor of the Year for content that advances engineering and design.