64-GBaud BERT simplifies setup and accelerates 400G receiver test

September 20, 2017 //By Jean-Pierre Joosting
Streamlining receiver test setups with a highly integrated pattern generator, the M8040A from Keysight Technologies is a high-performance bit error ratio tester (BERT) for PAM-4 and NRZ devices that operate up to 64 GBaud. It delivers repeatable results with built-in equalizer to reopen closed eyes.

Engineers in validation labs and R&D who characterize receivers on the physical layer for emerging 400G data center interconnects will benefit from simplified test setups and repeatable and accurate results.

The latest revisions of IEEE 802.3bs and OIF CEI-56G implementation agreements define PAM-4 and NRZ interfaces for electrical chip-to-chip, chip-to-module, backplane connections and optical interfaces for up to 400 Gb/s bandwidth. R&D and validation labs that need to characterize receivers for data center interconnects with PAM-4 or NRZ data rates up to 64 GBaud are facing new test challenges, such as tighter timing margins, channel loss, non-linearity, level interference and crosstalk effects—making test efficiency and accuracy essential.

Overcoming channel loss in electrical interfaces, such as chip-to-chip, chip-to-module interfaces and backplanes, is a big challenge with higher symbol rates. Pre-distortion techniques, such as de-emphasis, are used in the transmitter and equalization in the receiver to help re-open closed eyes caused by inter- symbol interference.

Scalable and upgradable for future needs, the M8040A is the latest member of the modular AXIe based M8000 series of BER test equipment. This highly integrated BERT supports PAM-4 signals up to 64 Gbaud and NRZ signals up to 64 Gbit/s. The pattern generator module provides built-in de-emphasis, jitter injection and an optional second channel. Engineers and designers can select PAM-4 and NRZ by software in the user interface, eliminating the need for external combiners, cabling and deskew to provide PAM-4 signals. For best signal quality, remote heads reduce the distance to the device under test. The analyzer module provides true PAM-4 error analysis in real-time for long PRBS and QPRBS patterns—allowing proofing even low-bit error ratios and symbol error ratios with the required confidence.

The error analyzer now supports symbol rates up to 64 Gbaud for NRZ signals and built-in adjustable equalization. Users can control the M8040A from a graphical and remote-control interface.

www.keysight.com