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DARPA Creates 0.85 THz Solid State Receiver
hypnosec writes "DARPA, under its THz Electronics program, has designed a solid state receiver capable of THz (terahertz) frequencies thus inching towards the possibilities of transistor-based electronics that will operate at THz frequencies. The newly designed solid state receiver demonstrates a gain at 0.85 THz. This particular milestone is a stepping stone for the next target of 1.03 THz. Because of this achievement a host of DoD electronics capabilities can now be realized. One such application where this can be of use is for a sensor that will operate through clouds under a DARPA program dubbed VISAR."
Not just for airports any more. With technology like this, they can start minaturising the tech so every cop doing a stop-and-search can inspect the suspect. For, ah, weapons. Of course.
It's "gain at 0.85 THz", not "of".
Article summary is incorrect.
Sorry, EE major and I get annoyed reading this kind of thing...
This (PV antennae) is even more interesting application.
Upward mobility is a slippery slope - the higher you climb the more you show your ass.
I want to make an oven with these things! Just think, the speed of a microwave with th heating properties of a regular oven!
I'm and so there! The T-Wave oven!
Since microwaves use GIGAherts frequency and have MILLImeter wavelengths, why do they call them MICROwaves? :/
Here is what they want this for:
This revolutionary advance would give U.S. warfighters an advantage in an especially challenging portion of the RF spectrum
As per usual, it's all for war, it's all that government is interested in.
You can't handle the truth.
I can do morse code at 1Hz, also known as 0.000000000001THz. Look! THz frequencies. 0.85THz is fast, but just because you used THz as the unit of measurement doesn't mean you have accomplished THz speeds.
Another terrible article summary.
In 2010, a solid-state device at 0.67THz was achieved. In 2012, that effort is up to 0.85 THz. Progress is slow, but continuing.
Diode-type CMOS imagers for terahertz radiation have been built. Those convert terahertz radiation into DC, which can then be amplified by standard techniques. But diodes don't have gain. That's why the original article emphasizes that this new device has gain.
There are terahertz lasers, waveguides, antennas, and other components that work up there. The situation is much like radar during WWII; there were a few components that could do specific things at radar frequencies (then 60MHz to 1.2GHz), but general electronics wasn't there yet. Most of the electronics in radars of that period ran at far lower speeds. They still worked.
Probably unity gain at 0.85 THz.
Let's not make it bigger than it really is !! My ethernet is 10 GHz !! And it's punky PC stuff !!
... or are they going to try to make a CPU/GPU core at this speed?
In the long run, maybe. In the short run you aren't going to like it. A very stereotypical microwave LNA MMIC operating around a factor of 100 lower then this device frequency (in other words, cheap and off the shelf) consisting of a couple transistors is biased much like a LED... couple volts, couple dozen mA. Lets call it 4 volts at .040 amps thats 160 milliwatts per device. For rounding purposes lets say a tenth of a watt per transistor. So if you have a roughly quarter million transistor original 386 a 10 GHz discrete 386 made out of microwave transistors would draw about 30 or so KW. Which is quite a lot of power. Of course you don't need low noise small signal performance or great fan in / fan out ratios... Regardless high speed individual devices certainly like their DC power.
The problem with making processors fast is keeping them fed with something to do. CPU tech always seems to lead memory/IO/algorithm design, I can't remember an era when the "memory guys" were waiting on the "processor guys" to catch up. With current tech a 1 THz CPU would merely spend 99.9% of its time in idle waiting for memory... But nothing in the world could run a NOP or an endless loop faster than that device.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
>... or are they going to try to make a CPU/GPU core at this speed?
The receiver is analog electronics, not digital.
That could also be used for transmission purposes.
now we need to go OSS in diesel cars
I'm not expecting some CPU at the capacity level of an x86 or even ARM chip. Something smaller would make sense. Very basic instruction set, few registers, no floating point, just something to provide logic control that can make decisions at rates above what today's host computers can barely get a clock pulse at. Maybe at best an 8-bit architecture, if even that.
now we need to go OSS in diesel cars
Wouldn't a 1.03 Thz EM wave, by definition, been what we call Infrared light? And if so, why the race for this when we already have tons of cheap options for generating and detecting infrared light? I realize I'm the daft one here and not the scientists, but could someone explain what the difference is between their (eventual) 1.03 Thz solid state "receiver" and say an off the shelf $0.20 IR detector that's been available for decades?
Which is why I didn't jump to the assumption it could just be used for digital purposes immediately. But, nicely linear analog is hard to do. There may be non-linear leftovers in the research.
now we need to go OSS in diesel cars
It may have demonstrated 0.1dB of gain at 850GHz (seriously, let's not label it THz unless it actually makes THz), but unless it is linear, it is pretty useless for digital communications.
My understanding is that L1 cache is as fast at the CPU it is embedded in. Just make more of it and watch how we make real-time raytracing instead of relying on polygonal tricks for rendering 3D.
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
Does anyone here know of the term "Terahertz radiation"? Why are people saying things like "my eye is a Terahertz receiever" or "0.85 Terahertz isn't really Terahertz"?
http://en.wikipedia.org/wiki/Terahertz_radiation
The summary and linked press releases are light on details so here is what I gleaned from the photograph of the chip based on some experience in the area of microwave/mm-wave device and circuit work. There will probably be much more technical information in upcoming papers in the research literature.
Based on the photo of the chip on the linked DARPA page this is not a receiver, but a low-noise amplifier (LNA) which would be used as the front-end for an imaging sensor or communications/radar receiver. It would be straightforward to turn this into an imaging detector at this point by adding a detector after the LNA though I don't think this has one. For a synthetic aperture radar more circuits will be required, especially a mixer to downconvert the frequency.
The slashdot summary misquotes the article saying that the circuit has "gain of 0.85 THz" but should say "gain at 0.85 THz". The LNA appears to have 10 amplifications stages which is very large for a LNA, which suggests that the gain per stage is still quite low at 0.85THz. This is to be expected as the best per-transistor gain cutoff frequencies are not too far 1THz that I'm aware of. The circuit also appears to be built in coplanar waveguide (a metallized signal strip in the middle surrounded by two ground strips) which is easy to fabricate and good for a research environment but it has a higher loss than microstrip (a signal line above a ground plane).
Anyway that's my 2 cents.
Just like me, I have mega-bucks. 0.000002 million bucks in my pocket right now! If I put it in the bank, with interest it will have gain.
The first of which you really need. The essential element to a near-terahertz receiver is that it can downconvert 0.85 THz to a more easily processed frequency.
With current tech a 1 THz CPU would merely spend 99.9% of its time in idle waiting for memory... But nothing in the world could run a NOP or an endless loop faster than that device.
This is incorrect, common DDR3 memory is already 2 orders of magnitude slower than a 3 Ghz CPU and they work just fine.
With a THz CPU you also have THz memory (registers, level 1 cache, etc.), if your algorithm fits in the cache you will have close to 100% of the performance.
So this thing can receive signals at (just less than) a TeraHz... But is somebody transmitting on that frequency?
Obviously the higher the frequency the more bandwidth is available but what about the characteristics of the atmosphere ? Is this for long distance communication? wouldn't clouds etc screw it up?
When a government agency funds something that works, the headline is always, "NASA builds this..." or "DARPA builds that..."
But when a government agency funds something that doesn't work, the headline instead is, "Lockheed mess up this..." or "Boeing messed up that..."
Did DARPA "create" this as the headline says, or did they just fund somebody else to do the research, design and implementation?
http://www.laserfocusworld.com/articles/2012/07/northrop-grumman-demos-850-ghz-integrated-receiver-circuit-aiming-at-terahertz-photonics.html
I hope that after I die the one word people use to describe me is "resurrected."
My understanding is that L1 cache is as fast at the CPU it is embedded in. Just make more of it and watch how we make real-time raytracing instead of relying on polygonal tricks for rendering 3D.
But the rest of memory isn't keeping up. That's why in modern CPUs a ridiculously high proportion of the die is cache, and it's still not enough: modern CPUs already spend a lot of time just waiting on main memory.
Geordi La Forge's VISOR allowed him to see between 1 hz and 100,000 THz. Isn't it kinda interesting that they used a name so similar?
When I was doing war toys, not all that long ago, (ok, I guess it was. Where did the time go?) 40 Ghz was considered really, really high.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
"VISAR seeks to develop and demonstrate a targeting sensor which operates through clouds as effectively as today’s infrared (IR) sensors operate in clear weather. This revolutionary advance would give U.S. warfighters an advantage in an especially challenging portion of the RF spectrum.”
The wars of the future will not be fought on the battlefield or at sea. They will be fought in space, or possibly on top of terahertz waves.
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All digital electronics is ultimately analogue. If you had transistors that could run at that speed, you could probably sample at (at least) a quarter of that speed. Make a very nice ADC/DAC for a software (de)modulator and fixed function DSPs.. Lots of digital applications on the digital side, if the power draw is reasonable.
I have determined that my sig is indeterminate.
it goes to 11.
Yes, I joke there. I do find it fascinating how stuff keeps getting pushed to the limits, and then we say "bah, we can do better!"
Vote monkeys into Congress. They are cheaper and more trustworthy.
How compares the CPU die size with the distance that the signal travels at this speed ? Right.
I can't remember an era when the "memory guys" were waiting on the "processor guys" to catch up.
You must be young. Look at Woz's design for the Apple 2.
Look for when they started putting cache on CPUs.
The data bits won't even have time to cross the distance from the cache to the registers in 1 clock at 1 THz.
That is why I am talking about raytracing : you need far more operations per pixel than what we have today.
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
Its a design issue. You won't like it because its a PITA. Google for "Peristaltic Array" and apply it to cpu components/microcode instead of the somewhat more popular higher level implementation. Theres about a zillion other high performance computing ideas, mostly unchanged since the 60s and 70s (although continually reimplemented up to current time)
I designed and simulated (in MS basic) a system like this many years ago for fun that operated at KHz speeds (reimplementing in the then unheard of GHz range or THz would be a mere implementation issue). The architecture looks very "streaming" or more like a reconfigurable on the fly FPGA. The main bottleneck for current implementations how do you wedge a multidimensional problem in a fundamentally 2D FPGA and how do you get a FPGA thats big enough to hold fun stuff but small enough that it loads up quick.
Needless to say its a near total decoupling of math and control flow. You might have 10, 100, even 1000 vector items in the stream squirting out one result per cycle, but a control flow loop can only be as fast as light can cross the whole device as you say. Also if you have 1000 items in the pipeline, although this seems obvious, many people don't realize it takes 1000 cycles for the first result to squirt out, which makes it "slow" for anything but repetitive stuff. Although you can play creative games with tossing out data and such, and the ickyness surrounding it it why you won't like it.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
The most important question: how will we divide the THz bands into Extra, Advanced, General, Technician, and Novice?