High-speed serial data
All the data that goes to mobile and wired devices comes from datacenters and is then carried over high-speed electrical and optical serial links to and from their destinations. Those links stress the limits of transmitters, receivers, interconnects, PCBs, and anything else along the way. That's the focus of DesignCon 2015.
100 Gbit/s serial links consisting of 28 Gbit/s and 32 Gbit/s lanes have been the subject of DesignCon for several years. Now, talk of 56 Gbit/s lanes is erupting. The industry has yet to settle on a modulation form (NRZ or PAM4) so right now, both are in development for 56 Gbit/s links. Both of these modulations will be subject to BER (bit-error rate or bit-error ratio) tests.
"BERTS (BER testers) will have to measure at speeds such as 28G/32G, while having the scalability to support higher data rates such as 56G NRZ or 56G PAM4," said Hiroshi Goto, Business Development Manager at Anritsu and a frequent contributor at DesignCon. "BERTS will have to provide pre-emphasis and de-emphasis on multiple channels to conduct cross-talk tests. Engineers will need to inject accurate and repeatable jitter into serial data streams for jitter-tolerance tests."
Not only do data rates increase, but the amplitudes of digital signals decrease, making signal integrity even more of an issue. "These changes are introducing stringent requirements for transmitter, receiver and channel tests. Distortions such as jitter, ISI (intersymbol interference), and noise have to be carefully accounted. Test engineers must be sure they are capturing and measuring the true signals, as opposed to wondering if what they are seeing is just an artifact of the test setup," said Keysight's Wallace."
Chris Loberg, Senior Technical Marketing Manager at Tektronix noted that researchers are already starting work on 400 Gbit/s and 1 Tbit/s optical links. They will further push the limits of signal margins in eye diagrams and as well as BER performance.
400 Gbit/s fiber-optic network tests are already underway as network providers scramble to find ways to drive more content through their backbones. "Imagine the demand for high-speed networking once Google Fiber and other competitive services begin providing 1 Gbit/s connections to the home," Loberg said. "To meet that need, a new generation of chips, controllers and modules will all need to be characterized and validated."
In addition to characterizing and validating ICs, engineers will need to characterize transmission channels: PCB traces, connectors, cables, and other components. That should drive the need for ever faster oscilloscopes and higher-frequency network analyzers. 2015 could also be the year that optics make a deeper penetration into silicon, PCBs, and cables. Several papers will cover optics at DesignCon 2015 including a panel discussion, Will the Optical Backplane ever happen?