Test Assemblies Enable SerDes Characterization Out to 90 GHz

Sept. 28, 2023

The latest addition to Samtec's Bulls Eye series of test connector systems gives test engineers the ability to characterize 224-Gb/s PAM4 SerDes links.

David Maliniak

Related To: Microwaves & RF

This video is part of the TechXchange: Vector Network Analyzers.

We recently caught up with Dan Birch, global RF engineering manager at Samtec, who showed us the company's latest addition to its Bulls Eye lineup of high-performance test assemblies: the BE90A. It provides usable bandwidth out to 90 GHz.

Such assemblies are critical to accurate characterizations of the serial/deserializer (SerDes) interfaces found in extremely high-speed communication links. The Bulls Eye test assemblies feature a high-density, space-saving design that enables smaller evaluation boards and shorter trace lengths in test and measurement applications (Fig. 1).

1. Samtec's range of Bulls Eye compression-mount test assemblies covers the needs of test engineers looking to characterize SerDes links from 40 GHz up to 90 GHz.

The Bulls Eye block mounts to the board directly adjacent to the SerDes being characterized. Its solderless design improves overall cost and is easy to use within a lab setting. End 2 of the cable assembly connects to instrumentation using any of the following connector options: 1.00, 1.85, 2.40, or 2.92 mm.

For near-perfect fidelity for 224-Gb/s PAM4 SerDes characterization, the new BE90A is the assembly of choice. However, as shown in Samtec’s live 224-Gb/s PAM4 demonstration, the 70-GHz BE70A assembly is also capable of handling 224-Gb/s PAM4 when taking certain signal-integrity optimizations into consideration.

These high-speed interfaces have become so prevalent that the need for multichannel, high-speed, compression-mount connectors with very high signal integrity has steadily grown. Samtec’s Bulls Eye assemblies have been adopted for use in clock/data recovery (CDR) for communications, mmWave radar systems, automated test equipment, next-generation FR2 5G networks, and a variety of custom high-density high-performance designs. Single-row options are also now available, supporting smaller board real estate in emerging high-performance, high-density applications.

Here's a transcript of the video (it has been edited for clarity):

What we're demonstrating here is the latest in our Bulls Eye test connector system. This is a compression-mount test connector system that allows our customers to make a lot of high-speed connections very quickly on a very-small-area printed circuit board.

2. Here one may see the BE90A's insertion-loss characteristics measured using a 50-Ω CPW transmission line and a six-layer PCB. Results include the breakout region and BE90A cable assembly with all other effects removed by de-embedding.

The latest generation here is BE90A and the system's got 90 GHz of usable bandwidth. So we have a signal source on the VNA coming in with a 1-mm connector and cable, and that's coming in to this cable on the Bulls Eye 90 system.

A 0.47-mm cable comes into the Bulls Eye connector, goes through about 2 inches of micro strip, and out through a 1.35-mm test port or a vertical launch connector and back to the VNA. We've de-embedded that and the net result is we've got just more than 5 dB of insertion loss all the way out to 90 GHz and almost 15 dB of return loss (Fig. 2) . So, as I mentioned earlier, there's a lot of usable bandwidth here with the system and that's what we're shooting for. So if you have any more questions, feel free to go to our website for more information.

Check out more videos/articles in the TechXchange: Vector Network Analyzers.

About the Author

David Maliniak | Executive Editor, Microwaves & RF

I am Executive Editor of Microwaves & RF, an all-digital publication that broadly covers all aspects of wireless communications. More particularly, we're keeping a close eye on technologies in the consumer-oriented 5G, 6G, IoT, M2M, and V2X markets, in which much of the wireless market's growth will occur in this decade and beyond. I work with a great team of editors to provide engineers, developers, and technical managers with interesting and useful articles and videos on a regular basis. Check out our free newsletters to see the latest content.

You can send press releases for new products for possible coverage on the website. I am also interested in receiving contributed articles for publishing on our website. Use our contributor's packet, in which you'll find an article template and lots more useful information on how to properly prepare content for us, and send to me along with a signed release form.

About me:

In his long career in the B2B electronics-industry media, David Maliniak has held editorial roles as both generalist and specialist. As Components Editor and, later, as Editor in Chief of EE Product News, David gained breadth of experience in covering the industry at large. In serving as EDA/Test and Measurement Technology Editor at Electronic Design, he developed deep insight into those complex areas of technology. Most recently, David worked in technical marketing communications at Teledyne LeCroy, leaving to rejoin the EOEM B2B publishing world in January 2020. David earned a B.A. in journalism at New York University.