04-15-2014 08:37 AM
04-15-2014 08:50 AM
04-15-2014 09:04 AM
04-15-2014 09:22 AM
04-15-2014 10:02 AM
04-15-2014 11:33 AM
04-15-2014 11:40 AM
"lossofmercy" wrote:
Wow, that's pretty amazing. Cheap production of high quality graphene? Wasn't expecting that for a while. Here is how it works: [>]
Hope they can use it for those 427 ghz processors!
04-15-2014 11:58 AM
So, let's take that 845 GHz number. Loosely speaking, that's a single transistor changing states 845 billion times a second, meaning a single state change takes 1/845,000,000,000th of a second.
Let's suppose for a moment that information could be transmitted through the chip at the absolute fastest speed possible, the speed of light. In that 1/845,000,000,000th of a second, information could have traveled a maximum of 0.354 millimeters.
For comparison, Intel CPU dies for the current 22nm node range from 160 to 264 mm2. If the die is a perfect square, that comes out to 12.65 to 16.2mm on each side. That means that the longest dimension is going to be 17.9 to 23mm, from corner to corner.
That means that in this ideal scenario, where our information is traveling at the speed of light, the results of one calculation will take between 50 and 65 cycles to reach the other end of the chip, and twice as many cycles before the signal can get all the way back to the original end of the chip.
I hope that helps to show why the speed of a single transistor is pretty meaningless when we're talking about an entire CPU. It's kind of like quoting the fastest speed a tire has ever gone, probably by being shot out of a cannon or something similarly ridiculous. It tells you nothing about how fast an entire car can travel, because a single tire and an entire car simply aren't comparable.
The silicon-germanium heterojunction bipolar transistors built by the IBM-Georgia Tech team operated at frequencies above 500 GHz at 4.5 Kelvins (451 degrees below zero Fahrenheit) - a temperature attained using liquid helium cooling. At room temperature, these devices operated at approximately 350 GHz. Performance measurements were made using a specialized high-frequency test system in the Georgia Electronic Design Center.
04-15-2014 12:46 PM
04-15-2014 12:49 PM