Hi and welcome to another in the Arm “What Is” program series. In each episode, we dive into a
tech topic to give you insight and perspective into some of today’s hottest design trends.
I’m Brian Fuller, editor-in-chief at Arm and today we’re going to find out
what is an SoC? Or to spell it out, a system-on-chip?
And to help us with that, I want to introduce Richard Grisenthwaite, who is senior vice
president, chief architecture and Fellow at Arm. When he’s not helping us understand what
is an SoC, he enjoys hiking the West Highland Way in Scotland, which took him seven days.
Welcome Richard, let’s dive right in!
What is an SoC?
I think you said it yourself at the start there Brian. An SoC is a System-on-Chip. It was term
that came into currency when the amount of stuff you can integrate onto a single piece of silicon
got to the point that you didn’t need to put series of discrete chips onto a board. And this
really started on the smaller end of things into microcontrollers space where relatively
simple processor and were able to put memory in some peripherals around it onto a single piece
of silicon. And as Moore’s Law has continued to give us more transistors, we’re able to
integrate more things into a piece of silicon. So bigger and bigger systems are capable of
being built as the entire system on SoC rather than a big board with your GPU separate or
memory controller separate, it all becomes on every single piece of SoC.
We saw this in particular in the case of Arm, we saw the mobile space being big users of SoCs
and we’ve seen more and more functionality come onto that as our phones become more and more
capable with the whole smartphone revolution. And now for more, even bigger infrastructure
computers such as Neoverse N1, which is going into things like Graviton G2 From AWS. Those
systems are using SoCs rather than a collection of discrete components on a board.
You mentioned this growing functionality that design teams are putting onto SoCs.
Is there any limit to that functionality or to put it in another way, is there more
interesting functionality that is coming in the next couple of years?
I think it is just a question of increasing integration as the sizes of transistors keep
on getting smaller as we go down to five and three nanometers right about now, we see that continuing
on for a bit more then you’re able cram more and more functionality onto that. We’re already seeing
an order of a hundred CPUs now on a single SoC, which was an incomprehensible amount if you go
back 20 years ago. Nobody could have imagined being able to put anything like that level of
functionality on there. So it really comes down to the size of transistors as to limits
and we’re now talking about very, very big systems that will fit onto a single SoC.
What are some of the design considerations that
would prompt the design team to choose an SoC versus say buying an off-the-shelf chip?
Well, I think part of it is the financial model here. Clearly, the design and fabrication of an
SoC is an expensive thing to do because you got to create masks and run wafers and do all of that.
But once you’ve spent that upfront cost, then the cost of the end product can be
a lot cheaper per unit than assembling a list of different components and it can be
completely customized to what you want. It’s really not so much a design consideration,
it’s just pure economics. If you expect a large run of your design, you want to be very specific
to what you are doing, you can justify the expense, the upfront NRE of building an SoC.
Then it’s the right direction to go in because you get exactly what you want and you’re able to
have precisely that functionality at a lower cost per unit once you’ve amortized that initial cost.
Are SoCs used in a limited number of applications or are they more broadly applicable?
Well, I think, kind of the story I was telling at the start of this is what we’ve seen is initially
if we went back twenty years ago, people would have said, “Oh SoCs, they’re only useable for
relatively small, simple computers.” Imagine the mobile phone before we had smartphones when they
were relatively simple computing devices. No one would imagine putting an entire server onto
an SoC at that point because it really didn’t make sense in terms the amount of integration,
we were able to achieve. What has happened is as we’ve been able to achieve more integration onto
a single chip and as we get also 3D effects where you’re able to put multiple chiplets together onto
a single package, then you end up being able to pretty much solve
every problem. This is why even though the big infrastructure solutions such as the Graviton G2
are moving into the SoC solution. In many ways, this is just where all computing is going to go
is they are going to be made out of SoCs based around Arm. And that’s actually a big part of
Arm’s advantages by being a component supplier to people who want to build SoCs. They’re able
to build precisely the SoC they want. So we see this as a really important market going forward.
Well, thank you Richard! That was a fantastic explanation of SoCs!
Now, check out all our other “What Is” episodes here and be sure to subscribe to this channel
because we’ll be adding more as the year progresses. Thanks for listening!