PAM-4 analysis software developed for oscilloscope platforms

Posted By : Mick Elliott
PAM-4 analysis software developed for oscilloscope platforms

Measurement application software designed to help engineers quickly and accurately measure and quantify PAM-4 (Pulse Amplitude Modulation with 4 amplitude levels) signals has been launched by Keysight Technologies. The software is used with the Keysight S-Series, 90000A, V-Series, 90000 X- and Z-Series real-time oscilloscope platforms and the 86100D DCA-X Infiniium sampling oscilloscope.

The N8836A PAM-4 analysis software (for S-Series, 90000A, V-Series, 90000 X- and Z-Series oscilloscopes) and the new N1085A PAM-4 analysis software (for 86100D oscilloscopes) provide comprehensive characterisation of electrical PAM-4 signals based on the Optical Internetworking Forum’s Common Electrical Interface (OIF-CEI 4.0) proposed 56G interfaces, and the emerging IEEE 400 Gigabit Ethernet (P802.3bs) standard.

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, but excessive channel losses and crosstalk on 56 Gb/s NRZ links make this technology impractical for many applications.

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.

However, there is not yet consensus within the governing bodies of communication standards as to how to measure PAM-4 signals for compliance.

“Our customers face new design and measurement challenges as they work to ensure their products are compliant with specifications that are incorporating PAM-4 signalling,” said Dave Cipriani, vice president and general manager of Keysight’s Oscilloscope and Protocol Division. “We’re working with industry leaders and standards organisations in these very early stages to help customers address these challenges and get to market quicker.”

The N8836A and N1085A PAM-4 measurement applications for S-Series, 90000A, V-Series, 90000 X- and Z-Series real-time oscilloscopes and 86100D DCA-X Series sampling oscilloscopes deliver measurements such as Eye Width (EW), Eye Height (EH) and jitter measurements, including even-odd jitter and clock random jitter. Linearity and output voltage measurements include level separation mismatch ratio (RLM), and differential and common mode return loss measurements can be performed using a Keysight Time Domain Reflectometer (TDR) or VNA.

Multi-level signalling systems are particularly susceptible to noise, so Keysight’s V-Series, Z-Series and S-Series and offer low noise floors for wide-bandwidth, real-time oscilloscopes.

The N1085A’s measurement capabilities are supported by a variety of DCA plug-in modules such as the 86108B 50GHz precision waveform analyser module, the N1045A 60GHz module, or the N1055A 50GHz TDR/TDT module. Engineers can use the N1045A and N1055A modules to analyse up to 16 PAM-4 channels simultaneously.



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