PAM-4 analysis capability for real-time oscilloscopes

March 26, 2015 // By Jean-Pierre Joosting
Keysight Technologies has introduced measurement software designed to help engineers quickly and accurately characterize PAM-4 (pulse amplitude modulation with four amplitude levels) signals using the the company's V-Series, Z-Series, and S-Series real-time oscilloscope platforms.

The N8827A PAM-4 analysis software (for V- and Z-Series oscilloscopes) and N8827B PAM-4 analysis software (for S-Series oscilloscopes) provides comprehensive analysis of electrical PAM-4 signals.

Mobile computing applications are demanding more of the underlying computer Internet infrastructure. To enable increases in Internet and server-farm performance, higher-speed connectivity among server systems is required. Conventional communication techniques often relied upon NRZ (non-return-to-zero) encoding. Industry experts contend NRZ will not work in a 56-Gbit/s environment. One way to overcome this challenge is to change the modulation technique from NRZ to pulse amplitude modulation. This allows engineers to dramatically increase the amount of data they can send across high-speed digital communication links.

Several industry standards bodies are actively promoting PAM-4 technology to enable the next-generation speed class and push higher data rates for a given channel compared to traditional NRZ signaling. While PAM-4 technology leverages some traditional NRZ measurement algorithms for PAM-4 signals, to fully analyze system performance, unique PAM-4 measurements and parameters are required.

“Our customers face many new design and measurement challenges as they make the switch from NRZ to PAM-4 signaling,” said Dave Cipriani, vice president and general manager of Keysight’s Oscilloscope and Protocol Division. “By delivering both analysis and debug capabilities for PAM-4 signals, our latest PAM-4 analysis software for our real-time oscilloscopes helps engineers address these challenges and quickly get their designs to market.”

N8827A/B PAM-4 analysis software offers measurements such as: eye width, eye height and eye skew; level amplitude, level noise and level skew; as well as amplitude level linearity.