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NTT Verifies Diamond Semiconductor Operation At 81 GHz
Anonymous Coward writes "This story over at eetimes.com reports of a semiconductor made of diamond that is able to run at 81 GHz." Mmmm, foreshadowing.
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Vacuum tubes are still used as the final amplification stage for TV and radio broadcast transmitters. They're the best thing able to handle the power efficiently, even today. Try building a semiconductor transistor with a gate width measured in centimeters (compared with microns); it's tough.
81GHz is the switching speed of the transistor, not the processing speed of a resulting PC. Some of the reasons are:
* CPU's perform a large number of transistor switches in a single clock cycle.
* The rise/fall response time must be much smaller than the switching time.
Don't be uninformed...oh wait this is slashdot. Vacuum tubes are still used in RF broadcasting, especially digital TV because the are able to reach the power levels necassary to broadcast a 50kW radio signal at low enough distortion to cleanly transmit the digital signals.
This lengthy article gives a fascinating history into how the DeBeers cartel has created artificial scarcity in the diamond market and convinced the western world that a "Diamond is Forever". Before the 19th century, no one ever had to spend 6 weeks salary on an engagement ring!
There are some really great uses for vacuum tubes. Here's a couple:
1) High quality audio reproduction. Any home audio freak will tell you nothing sounds like a sweet tube amp. There is both anecdotal and scientific evidence for the superiority of tubes versus semiconductors. Why then do we use semconductors as audio amps? Price and size. For a home theater amp, semi's cost anywhere from $100 to $900+, and tubes cost anywhere from $500 to $20,000.
2) High frequency amplification. Good for rf transmitters. They have many other high frequency uses as well.
Don't discount the tube!
You can't legislate goodness. Let each to his own destiny, by will of his freely made choices.
DeBeers is shitting a brick over it too, because that means its nearly impossible to tell a diamond from the ground from a lab one, except the lab one is even purer. The good part of this is the tech industry has far more muscle and clout than DeBeers does. DeBeers is truly an evil company sown on the blood of africa and putting them out of business would do the world a favor.
In fact, the only way for this technology to become realistic is for large scale lab diamond growing like I mentioned above. Its still many years off.
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well, one of diamond's characteristics is high thermal conductivity, so presumably generated heat could easily be carried away with heat-sinking technologies.
make world, not war
Because you have to run those signals over wires, which do a really crappy job of conducting a high speed signal. On chip cache is certainly fast - just expensive (real estate and fabrication errors)
At the sort of frequencies we're currently using, circuit tracks look more like inductors and capacitors than bits of wires. They essentially act as antennas, and there is a massive amount of effort spent in trying to avoid those effects.
I was a little surprised nobody mentioned this story that was posted recently here.
If this man and his product really pan out, we could see some eally exciting advances in the semiconductor industry. But there could be a billion dollar enterprise that might think otherewise.
A quote from said artice:
But De Beers wasn't backing down. Throughout 2000, the cartel accelerated its Gem Defensive Programme, sending out its testing machines - dubbed DiamondSure and DiamondView - to the largest international gem labs. Traditionally, these labs analyzed and certified color, clarity, and size. Now they were being asked to distinguish between man-made and mined. The DiamondSure shines light through a stone and analyzes its refractory characteristics. If the gem comes up suspicious, it must be tested with the DiamondView, which uses ultraviolet light to reveal the crystal's internal structure. "Ideally the trade would like to have a simple instrument that could positively identify a diamond as natural or synthetic," De Beers scientists wrote in 1996, when the company unveiled plans to develop authentication devices. "Unfortunately, our research has led us to conclude that it is not feasible at this time to produce such an ideal instrument, inasmuch as synthetic diamonds are still diamonds physically and chemically."
Faster switching speed does have benefits in power reduction.
One on the main causes of heating in semiconductors is the switching performance. Whilst a transistor is "on", voltage accross it is zero (or near to), current high, power dissipation (equals voltage * current) is low. Whilst a transistor is "off", voltage accross it is high, current is zero, power dissipation low. However, during the transition from on/off, voltage and current levels are both intermediate, hence power dissipation occurs. Faster switching response times means less dissipation during switching.
One reason which another poster mentioned is the data transfer over the bus between the CPU and Main Memory, this is usually a few inches which means the signal can take more than 10ns to travel along the bus (which is a significant amount of time in chip design).
Another reason is that SRAM is used in a CPU for cache - its VERY fast but takes up more silicon per bit and is very expensive per bit.
Main memory is generally made of DRAM which is slower but also much smaller so you can get a much larger amount of memory onto a chip and much cheaper.
It's not that the latest technology isn't used in memory, it's just that its very expensive so it's used within the CPU as a cache while main memory will be slower in order to balance space vs cost for the machine to still be both affordable and usable.
Once the price drops, the cache technology gets put into main memory and a newer faster one replaces it in the cache.
The other big thing is that most of the advances in CPU speed are not due to the chip tecnology but due to design, especially pipelining.
CPUs go through a series of stages (eg fetch-read-execute) and the CPU can take advantage of this by running each stage while the next stage is still running.
This trick can't be taken advantage of in memory as memory does not contain several stages - hence pipelining increased cpu speed by something in the region of 5-10x while not increasing memory speed at all.
It's mainly new design tricks like this that have made most of the speed advances, which is why processor speed increases at such a larger rate than memory speed.
Very few people are understanding what the article is saying
The research teams have been able to fabricate semiconductor gates. In other words, they have probably been able to make a couple lone transistors (on/off electrical amplification switches) on a substrate lying in a lab with very controlled conditions -- long way off from computer processing.
You can run Doom on this about as easily as you can run Quake with your bedroom lightswitch...
There are some very undesireable things about semiconductors. They are low power devices. They don't work well at high frequencies. Couple these faults together and you let out the magic smoke on higher frequency applications (mostly Sat-Comms).
There are work arounds for the low power problem. In my job, (US Navy Electronics Technician) I've worked on an LF transmitter that could crank out over 150KW. It was all solid-state. The workaround to not cook silicon? It used about a freaking million amplifier circuit cards. I think it might have been more efficetive to just use 4 PA tubes but whatever.
Now the problem is high frequency and high power together. Consider the semiconductor. Two (slightly) different materials with a depletion region in the center. Well that's basically like a capacitor. Capacitors tend to pass higher frequency signals. If the signal is getting passed, it is not getting amplified. This problem is called inter-electrode capacitance. Tubes suffer from the same downfall. They dont just resemble capacitors, they are capacitors to a degree.
The tube world has to use some pretty crazy devices to amplify signals at high frequencies. These methods cannot transfer to the solid state world. For more information google for "klystron", and "travelling wave tube".
But because the issue of inter-electrode capacitance cannot be easily solved with workarounds. The only way to have a high frequency, high power amp, is with a tube. With higher quality semiconductors, this will no longer be true.
I wish there was some there was some way that I could be outside playing basketball, in the rain, and not get wet.
Apollo Diamond is now making near perfect crystal diamonds by vapor deposition. Their product has fewer flaws than natural diamonds. Since the diamond jewelry industry has been making a big deal out of "flawless" diamonds for a century, they're stuck - the industrial process is better than the natural one. Semiconductor process technology has been making near perfect crystals of silicon, quartz, sapphire, ruby, etc. for years, after all. This is just the next step.
Sapphires used to be rare gems. Not anymore. Linde Chemical started making synthetic star sapphires in the 1970s. Then sapphires went into volume production. Then the patents ran out. This is where the sapphire industry is now:
A few years, and bulk diamonds will be on the Home Shopping Channel.
Negative; the GM operation was shut down because all they could produce cheaply with their hydraulic presses was diamond powder. They actually were to the point where they could make contiguous crystalline structures bigger than dust; however, the cost far exceeded that of the DeBeers extortion and international crime fee diamonds. Though GM abandoned the project for purely financial reasons, I'm sure that DeBeers was happy about it nonetheless.
There was an article in the most recent Pop Sci or Discover (I can't remember which) abotu two companies that have successfully made large-karat diamonds synthetically. One company in Florida, Gemology I think, hastered the hydraulic press and can produce a 3-karat diamond, with few flaws, for $100. Another company out of Boston, I believe, uses a plasma deposition method that produces better-than-nature flawless diamonds... 3k for $15. And this latter process promises to be able to deposit not just chunks (i.e. jewelry), but wafers (i.e. semiconductors!)
Of course, the preseident of the latter of the two companies was at a diamond conference and was told by a DeBeers fellow that what he was doign was a good way to get a bullet in the head!
Wired 11.09: The New Diamond Age discussed on Slashdot earlier. Actually the link to the eariler /. story was posted above under "foreshadowing".
Future Wiki -- If you don't think about the future, you cannot have one.
1) SRAM is actually Static RAM. It's very vast but it also requires a LOT more transistors per bit than DRAM - Dynamic RAM. I do believe that SRAM also consumes more energy than DRAM (i'm not absolutly sure). Don't expect SRAM to be use in Main Memory anytime soon (unless people are willing to pay the same for 100M as they pay today for 1G - and i'm being optimistic here)
The typical SRAM structure is a 6T circuit (That is 6 transistors), while DRAM is 1T. DRAMS does however need to be refreshed with regular intervals as the capacitor that stores the bit is prone to leakage. This means the DRAM can never idle at virtually 0 power consumption.
SRAMs therefore consume a lot less power than DRAMs when there are significant idle cycles.