Find the settings and open the eyes

February 01, 2016 // By Martin Rowe
Serial data streams running at 28 Gbps and higher suffer from channel losses. To compensate for those losses, transmitters and receivers use equalisation and error correction techniques. A board may have hundreds of such high-speed links and systems can have thousands, with each pair needing its own settings.

Because each link's transmission path is often unique, engineers need to find the optimum Tx (transmitter) and Rx (receiver) settings to maximise signal integrity and eye-diagram openings. But, with thousands of settings at each end, where do you begin?

OptimEye from Signal Integrity Software (SiSoft) can take the pain out of what is often a tedious, iterative process for finding the best settings. It eliminates the "blind sweeps" often used to find the settings for each Tx and Rx pair.

"Transmitters and receivers start by connecting at low bit rates as they begin to negotiate settings," said SiSoft's Todd Westerhoff, "With millions of possible settings per link, optimising a board or system using this iterative process is impractical."

Because OptimEye has the models for each transmitter, receiver, and transmission channel (length, frequency response, signal loss, etc.), it can simulate them. Using statistical methods, OptimEye can predict settings for each Tx filter tap and Rx DFE (decision-feedback equalisation). So instead of spending hours with blind sweeps, you can run a few simulations to optimise each link.

SiSoft will be showcasing its OptimEye technology for automatically optimising eye margin in a forthcoming webinar, "A SerDes Balancing Act: Co-Optimizing TX and RX Equalization Settings to Maximize Margin," that will go live on February 23 rd 2016 at 20:00 CET/ 7:00 pm GMT/ 2pm EST. You can register for the webinar here

SiSoft, OptimEye product page