PAM analysis solution operates on 70GHz oscilloscope

PAM4 is being adopted in the latest 400 Gigabit Ethernet standard by the IEEE P802.3bs working group for 400G (typically 8 x 50G) electrical and optical interfaces. Compared to traditional NRZ that uses two-level signaling, the four-level scheme used in PAM4 significantly increases signal complexity and places new demands on test equipment for performance and noise sensitivity.

The ability to reliably characterise PAM4 signals from 13GBaud to 56GBaud with a common set of tools supporting both optical and electrical domains is key to advancing this new modulation methodology into the industry.

Analysis of multi-level signaling found in PAM4 requires an oscilloscope with low noise and good signal-to-noise ratio to accurately acquire and analyze the multiple bit states. The Tektronix DPO70000SX oscilloscope uses Asynchronous Time Interleaving (ATI) technology to deliver low noise acquisitions, as much as 30 percent lower noise than conventional frequency interleaved performance oscilloscopes.

Optical PAM4 measurement analysis benefits from low noise acquisitions as well. With the optical acquisition technology available with the DSA8300 Series Sampling Oscilloscope, Tektronix now offers the lowest noise and highest sensitivity in the industry today, even with full clock recovery in place. This new level of noise performance in the Tektronix 80C15/CRTP optical module is a great fit for optical PAM4 analysis with its full complement of TDEC and SR4 conformance measurement capabilities.

Features in the PAM4 Analysis toolset include the ability to analyse full waveforms or correlated waveforms, reference level settings for pass/fail analysis of multi-level thresholds, numerical rise/fall times for every LSB, MSB level, and built-in clock recovery using PAM-specific PLL models provided by Tektronix.

The full range of Tektronix 100G and 400G test solutions will be demonstrated in Stand 435 at ECOC 2015 (Sept. 28-30) in Valencia, Spain.