Pulse Amplitude Modulation (PAM-4) analysis on Keysight wideband ´scopes

January 28, 2015 // By Graham Prophet
Keysight Technologies has added a software option to accurately characterise PAM-4 (pulse amplitude modulation with four amplitude levels) signals using the Keysight 86100D DCA-X wide-bandwidth oscilloscope platform. Keysight 86100D-9FP PAM-N analysis software provides comprehensive analysis of optical and electrical PAM-4 signals.

PAM-4 is a type of multilevel signalling designed to increase the amount of data that can be sent across high-speed digital communication links. PAM-4 designs, for example, will likely enable the transition from 100 Gb to 400 Gb Ethernet speeds.

Keysight notes that industry groups and standards bodies are using, or actively considering using, PAM-4 technology to jump to the next-generation speed class and enable higher data rates for a given channel bandwidth compared to traditional non-return-to-zero (NRZ) signalling. While PAM-4 technology adapts some traditional NRZ measurement algorithms for PAM-4 signals, to fully analyse system performance, unique PAM-4 measurements and parameters are also required.

86100D-9FP PAM-N analysis software offers measurements such as:

- Eye width, eye height and eye skew

- Level amplitude, level noise and level skew

- Amplitude level linearity

The PAM-4 option may also be combined with existing DCA-X software options to provide more powerful analysis capability:

- PAM-4 equalisers (LFE, CTLE, DFE) using 86100D Option 201

- Embedding/de-embedding of PAM-4 channels using 86100D Option SIM InfiniiSim-DCA

- Jitter and amplitude analysis on IEEE JP03 patterns using 86100D Option 200/300

Multilevel signalling systems are particularly susceptible to noise, so the 86100D’s low-noise, wide-bandwidth plug-in modules are appropriate. 86100D Option 9FP PAM-N analysis capabilities are supported by all 86100D DCA-X plug-in modules, such as the 86108B precision waveform analyser module for accurate analysis of electrical signals to 32 Gbaud or the 86105D-281 for accurate analysis of high-speed optical signals. Engineers can perform offline analysis on saved or simulated PAM signals using N1010A Option 9TP PAM analysis software installed on a PC.

Keysight; www.keysight.com/find/86100D-9FP