I had no idea this would post today; was thinking about this all day yesterday.
Perhaps because I have been piecing together a server from eBay salvage. I have had to deal with pulling the PCIe signaling from the card slots (at the back of the box) to the hot-swap storage backplane (at the front). Re-timers versus re-drivers, or tri-mode host bus adapters, and all these different connectors that the industry thinks are a good idea.
Of course, silicon photonics will usher in a whole new world of connectors and cables.
What's the advantage of this? The need to use receivers that convert light back into electrical signals negates the speed advantage of light in communication. lol
Well, I wouldn't say that... It's often the case for companies to be drawn to something that seems promising at first glance, only to discover there's a significant caveat. They invest in the hope of resolving the underlying issues, but often find themselves forced to abandon the tech due to either draining their capital or failing to find a viable solution.
I believe the losses in copper at high frequencies are the problem. (If you push too much bandwidth, your signal just turns into heat after a few cm in copper). Optic fibres on the other hand largely get rid of that distance-bandwidth tradeoff.
I think you're painting with an extremely broad brush, when you say that. By the time someone like TSMC reaches the point of a product announcement, they've done enough R&D to know that the tech solves a real problem for their customers. They wouldn't undertake the costs involved in productizing such tech, unless it did.
AI is probably a key driver for this, given that 100 Gbps Ethernet seems to be a popular building block for the switched fabrics linking multiple accelerators. That's what Intel/Habana, Tenstorrent, and Cerebras are all doing, currently.
It increases the distance of low latency high bandwidth communication. You can connect up servers across a data center with photonics but with electrical signals you can do the rack next to it or maybe two racks over at most.
The power consumption needs to get well under one pico Joule per bit - with the data rates that TSMC are hoping for (12.8 Tbps) one pJ/bit would imply a power consumption of 12.8 watts in a very tiny space. Cooling such a hotspot would not be trivial.
That pJ/b figure should span from end-to-end (i.e. split between Rx and Tx). Given that it's currently implemented in 65 nm technology, it sounds like it might not be as small as you're probably assuming.
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watersb - Friday, April 26, 2024 - link
I had no idea this would post today; was thinking about this all day yesterday.Perhaps because I have been piecing together a server from eBay salvage. I have had to deal with pulling the PCIe signaling from the card slots (at the back of the box) to the hot-swap storage backplane (at the front). Re-timers versus re-drivers, or tri-mode host bus adapters, and all these different connectors that the industry thinks are a good idea.
Of course, silicon photonics will usher in a whole new world of connectors and cables.
PicoJoules per bit per second would be nice.
Dante Verizon - Sunday, April 28, 2024 - link
What's the advantage of this? The need to use receivers that convert light back into electrical signals negates the speed advantage of light in communication. lolnandnandnand - Sunday, April 28, 2024 - link
I guarantee these companies would not be bothering with silicon photonics if that was going to be a problem.Terry_Craig - Sunday, April 28, 2024 - link
Well, I wouldn't say that... It's often the case for companies to be drawn to something that seems promising at first glance, only to discover there's a significant caveat. They invest in the hope of resolving the underlying issues, but often find themselves forced to abandon the tech due to either draining their capital or failing to find a viable solution.stephenbrooks - Sunday, April 28, 2024 - link
I believe the losses in copper at high frequencies are the problem. (If you push too much bandwidth, your signal just turns into heat after a few cm in copper). Optic fibres on the other hand largely get rid of that distance-bandwidth tradeoff.mode_13h - Monday, April 29, 2024 - link
I think you're painting with an extremely broad brush, when you say that. By the time someone like TSMC reaches the point of a product announcement, they've done enough R&D to know that the tech solves a real problem for their customers. They wouldn't undertake the costs involved in productizing such tech, unless it did.AI is probably a key driver for this, given that 100 Gbps Ethernet seems to be a popular building block for the switched fabrics linking multiple accelerators. That's what Intel/Habana, Tenstorrent, and Cerebras are all doing, currently.
FreckledTrout - Wednesday, May 1, 2024 - link
It increases the distance of low latency high bandwidth communication. You can connect up servers across a data center with photonics but with electrical signals you can do the rack next to it or maybe two racks over at most.Duncan Macdonald - Sunday, April 28, 2024 - link
The power consumption needs to get well under one pico Joule per bit - with the data rates that TSMC are hoping for (12.8 Tbps) one pJ/bit would imply a power consumption of 12.8 watts in a very tiny space. Cooling such a hotspot would not be trivial.mode_13h - Monday, April 29, 2024 - link
That pJ/b figure should span from end-to-end (i.e. split between Rx and Tx). Given that it's currently implemented in 65 nm technology, it sounds like it might not be as small as you're probably assuming.