Understanding active electrical cables: a comprehensive guide

In this Vitex Talks segment, we’ll discuss the benefits of using AECs (active electrical cables) in data centers, particularly for those working with 400G applications. AECs are an alternative to DACs (direct attached cables) and can offer a longer reach, up to five times that of DACs, as well as reducing cable gauge and weight.


(0:00-0:22) Intro
(0:23-1:22) What is an AEC?
(1:23-3:24) What does an AEC do?
(3:25-6:06) What does an AEC bring?

Products Mentioned

400G AEC

Complete Transcript


Hey everybody! This is Craig at Vitex, and today we’re going to shine some light on AECs and why they’re important. If you’re in a data center, especially if you’re working on something like 400G, you may want to keep a listen because we’re going to go through some of the options that we have.

What is an AEC?

Traditionally if you’re in really short areas, a lot of you are going to be familiar with what a DAC is. That’s a direct attached cable, and it’s used in a lot of data centers, especially for very short reaches.

But we have this new product offering that came out not too long ago, and we’re going to talk about why that could be a good solution for you.

But first we want to just kind of tell you about some of the names that this goes by because depending on what you look up, you may find this under different names.

To kind of quote Shakespeare, “A rose by any other name.” It may work really well in literature and if you’re stuck up on a balcony, but not as much in optical communication.

The product we’re talking about today is the AEC. This is the active electrical cable. You may hear it referred to as an ACC, which is an active copper cable, or an ADAC, which is just the active DAC.

What does an AEC do?

What does this do and why do you need it?

As I mentioned before, DACs (Direct Attach Cables) have a constraint when it comes to length. But let’s just imagine we’re in a situation where we’re operating within those constraints. We can see our input, what’s coming on one side of the cable is what we’re going to get on the output, so there’s really nothing for us to do here–and this is totally fine.

Let’s talk about that situation where we’re going past the reach of what a DAC can support. And so, you have two options that you’re really going to look at from a technical space. One is going to be the re-driver, and this is important because as the signal goes farther and farther in reach, you’re going to lose amplitude. To get that back, we need to apply more gain to it.

This is what the re-driver does. It allows us to increase our gain on our signal and results in a longer reach. Let’s just assume that gain is not our problem and instead, it’s something related to time alignment. We could have an alignment kind of skewing going on. That brings us to the AEC re-timer option where it’s actually going to use a CDR (or a clock data recovery), and it’s going to realign that timing, so we get the high-quality signal that we’re expecting.

What does this mean, in terms of the kind of support and benefit we will get from it? Our reach is going to go up sometimes five times compared to a DAC. And if we’re looking at compared to other solutions, DACs really have the cable gauge which is really thick.

And if we want to reduce that, we can look at AEC as an option for this. Compared to other solutions, we’re going to see a really big drastic weight change, and we’re going to see the diameter of our cable drop. This is important when you’re looking at things like thermal management and airflow in data centers.

What does an AEC bring?

What else does AEC bring to you? It brings in a lot of DDM [Digital Diagnostic Monitoring] functionality, so you can do some pretty cool testing, and you can actually get reports from it.

There’s also the possibility of custom algorithms. This will do things like eye alignment, and it will check for things to improve our signal quality even more, so actually as our quality is going up, our bit error rate (BER) is going down. We can see drastic improvements in our bit error rate both over the distance that a DAC supports and as well as reaches further.

Let’s talk about some of the pros and cons of why we would use an AEC versus a DAC. DAC has a really great low latency, which is super awesome, so especially in like 400G applications, this can be very important. And our power consumption is also really low, so this is super important. But the bad part of this is we can only go a certain distance in that.

What if we want to get past that distance? We bring in the AEC re-driver and, again, this is just upping our game. We can still keep a low latency, low power, and we get this nice extension of reach. And in our other option, when we do our clock data recovery (CDR), we are going to see the latency suffer a little bit, and there’s going to be a slight increase in our power consumption because we have more active components in there. But we’re going to see this nice super jump in reach and we’re going to be able to get distances that we can’t with a DAC.

Another important consideration is the cost. When we look compared to a traditional DAC solution, the AEC with the re-driver, not too much more money. You get a little bit of increased cost when you go to a re-timer. But if you compare this to other solutions like AOCs or transceivers, it is definitely low.

If you want to find out more about this, feel free to give us a call, reach out to us in our New Jersey office and that’s all for this time, so until next time we talk, I’ll see you then.

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