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Sun Working to Eliminate Circuit Boards
lokedhs writes "Sun Microsystems is coming out with new chips without connectors. According to the article, this will have a lot of advantages: 'Performance, for instance, could greatly escalate because the speed of transferring data among chips and the number of channels for the transfers would increase. Energy consumption could also decline. Just as important, overall costs could fall, because defective chips could be removed like Scrabble tiles.' This technology will also lead to new CPU's without cache: 'The technique could also allow designers to remove the cache--the large pool of memory currently found on the processor--and put it on a separate chip. Caches were integrated onto processors to amplify bandwidth. Adding cache, however, bumps up manufacturing costs, as it greatly increases the number of transistors. With the bandwidth constraint gone, caches could once again be made independent without it having an impact on performance.'"
With so many chips so close together, they are certainly going to have heat problems.
Interesting technology, thought.
Did you even read the article before posting it here. The article talked about eliminating the pin that is used to house the chip. Due to the size of the pins, it limits the number of I/O paths a chip can expose to the motherboard. Instead they can implement transmitter/receivers using capacitive inductence to increase the I/O paths a chip can expose. Thereby increasing the bandwith a chip can utilize.
Think of it as lots of itty bitty low power radio transmitters and receivers.
Sounds clever to me. Electrical engineers have been constantly fighting unwanted interference in their circuits. Now they will be listening for it.
This was posted back in September of last year :
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http://slashdot.org/articles/03/09/22/1055244.sht
jdb2
The article mentions "capacitive coupling". Here is the relevant WikiPedia entry, and here's a paper on the specifics at Sun.
This side up.
As for the technique of capacitive coupling, that is how signals used to pass through low voltage amps virtually since the triode tube. The technique has been used for isolation amplifiers for many years. The signal on one side of the voltage barrier is digitised in some way (perhaps just PCM) and transmitted across a voltage barrier using very small capacitors, to where it is decoded. In some cases, power for the input side is also transmitted by capacitive coupling across the barrier.
Because the transmitting and receiving side of the capacitors is so tiny and the electric field therefore so constrained, it is not going to be possible to read the signals with an external aerial.
I believe Philips, among others, earlier suggested using LEDs and photodiodes along the edges of packages, but appart from requiring power they could only be unidirectional. Capacitive coupling itself absorbs begligible power and can be fully bidirectional.
Panurge has posted for the last time. Thanks for the positive moderations.
The problem with capacitive connections is that you are, for all intents and purposes, using small radio links. This causes several issues to come to the fore:
- Your immunity to cross-talk goes down. Misalignment will exacerbate these problems.
- Capacitive receivers will also be able to pick up local RF fields. The computer will be much more vulnerable to external interference than it was before.
- The computer will also radiate much more than it did before, creating more RFI and leaking information that might be crucial (like crypto keys).
Making the chips the meat in a sandwich with metal sheets for the bread would help this a lot, because tightly coupled ground planes attenuate both radiation and reception. As long as you're putting a ground plane on top of the assembly it might as well do double duty as a cooling device, though I wonder what effect the heat-transfer compounds would have on transmission and crosstalk.Sustainability and energy independence essay
Just to clearify to the un-initiated. It is the exact same technique that allows CMOS transistors to work (the basis of most CPU transistors).
CMOS-FET = Complementary Metal Oxide Semiconductor - Field Effect Transistor
That's semiconductors separated by oxide (oxidized silicone or glass) to allow fields derived from differing voltages on either side of the glass to affect conductivity and thereby provide actuatable signals. All this new system does is replace the Oxide with something else; namely the walls of the outside of the chip and the unavoidable air-gap.
Obviously this alternate medium is not as efficient as normal hyper-thin glass, BUT it's more efficient than transferring physical electrons from silicon to copper and amplifying it such that you can induce a measurable current down the coppy wire several centimeters away. More-over, it's more practical to etch micro-wire paths on the edge of a chip than to manually pin-punch chips like we do today. We can make such signal points smaller and more articulate.
The ONLY problem (as outlined in the article) is keeping these micro-signals aligned.. If you're off by even half a capacitive cell, then you're fields aren't going to be strong enough, and depending on cell-spacing, you're likely to generate noise to adjacent cells.
-Michael
so basically they want to stack the chips? umm, heat?
Re-read article. It's not a stack. They make reference to scrabble tiles as a comparison.
Even if it were a stack liquid cooling built directly into the stack, ala the internal combustion engine, could handle the heat effectively. Probably more effectively then our current heat sink technology.
TW
http://research.sun.com/async/Publications/KPDisc
jdb2
The solution to these problems are simple: you make the transmitters low enough power that they dont interfere with each other. From the Sun document I believe that the total power of each individual transmitter was on the order of 1-10 picojoules. That is precisely the reason alignment is such a prime concern - if the chips shift you have the wrong transmitters talking to the wrong receiver.
--Kevin
However, it's probably not a place to discuss it unless you have something to contribute to resolving it.