Boffins develop nanoscale vacuum tube running at .46 THz
Power hungry but radiation resistant relic could make comeback … in spaaaace
Researchers from NASA and Korea’s National Nanofab Center have cooked up nanoscale vacuum tubes, potentially bringing some of the earliest electronic devices back into the mainstream of technology.
As detailed in a new paper from Applied Physics Letters, the tiny tubes were manufactured using the same processes applied to silicon semiconductors. An important tweak sees a small cavity etched into silicon, bordered by a source, a gate and a drain. The cavity does not enclose a vacuum, but at 150 nanometres across is so small that electrons flowing through it are unlikely to bump into any other matter.
That setup means electrons can pass unimpeded, instead of having to struggle their way through silicon. Test rigs researchers have created show that data therefore screams along at up to .46 terahertz. The price of this power is power: firing up a device made of the tiny tubes needs 10 volts of juice, compared to one volt for a conventional transistor.
Because the circuits in the devices rely on the gap, they can also work well in nasty spots like space where radiation can knock physical circuits into literal disarray. The researchers are therefore rather keen on nano vacuum tubes as a way to harden computers on spacecraft, which today must pack all sorts of bulky and heavy radiation shielding.
As ever, while the researchers are chuffed with their lab work, no-one is willing to suggest a timeframe in which it will be possible to nip out to an electronics retailer and plonk down some cash for a nano-vacuum gadget. Assuming, of course, retailers still exist when the tiny tubes make it to market. ®
we measure power in volts now?
See you later Space Cowboy ...
'In space no-one can hear you play your Les Paul through a sweet nano-valve amp'
@LeeE -- Re: re:Since when were thermionic valves etc... -- Your point is a non-sequitur!
Your point is a non-sequitur--useless.
For heaven's sake, Robert E A Harvey is correct as he's just stating the well-known fact that valves once had widespread use in digital electronics. Moreover, when valves were used in digital applications they operated fully within their designed operational parameters.
Fact: Eccles and Jordan invented what's known as the Eccles-Jordan flip-flop aka multivibrator circuit, which is intrinsically a digital circuit AND IT ORIGINALLY USED VALVES/TUBES (practical semiconductor flip-flops had to wait until the perfection of the transistor some 20 years later in 1947). No argument!
The Eccles-Jordan and similar digital circuits were used in hundreds of applications before the transistor was perfected in '47. Notable digital applications that used valves/tubes include the sync timebase for 405-line TV--the first all-electronic television system invented in the 1920s by the famous EMI/Alan Blumlein team; Colossus, the first true digital computer used during WWII for code-braking at Bletchley Park, and also digital circuits found application in many other WWII electronics such as RADAR etc. Furthermore, various flip-flops were used in just about every TV set that used valves (i.e.: all TV sets worldwide made from 1930s to the early 1970s).
Fact: valves can act as switches by saturating or current limiting/running into clipping or hard-biasing them etc.--the circuits are numerous. When used in linear circuits such as audio and operational amplifies, valves are in fact harder to keep linear than transistors. For example, in an audio amplifier that uses valves it's hard to reduce the distortion to below about 1% although it can be done with effort, whereas it's not unusual to see a solid-state/transistor amplifier with a distortion in the order of 0.001% or less--and remember it's the transistor which is at the heart of modern-day digital electronics--not the valve. (It puts paid your stated argument that analog valves can't be used in digital electronics.)
Interesting fact: a single valve can act as both a digital switch and as a linear amplifier simultaneously! And this circuit, the super-regenerative receiver, was invented just on 100 years ago in 1913--some five years before the Eccles-Jordan flip-flop--by Edwin Armstrong, (Armstrong also invented the normal radio circuit that's almost exclusively used today--the superheterodyne receiver, and remarkably, he also invented FM radio).
The super-regenerative receiver is truly remarkable: [what follows is very simplified] a SINGLE VALVE, usually a simple triode, amplifies tiny RF signals received by the antenna using a regenerative positive-feedback process, it then quenches the feedback (stops the feedback taking off into a useless howl) with an oscillating/switching (digital) signal that's about double the frequency of the highest audio signal received, and so doing it detects the signal by rectifying it which is a diode-like switching process which makes the modulation on the RF carrier audible; and finally, it amplifies the detected audio signal which is then fed to the listener.
All up, the super-regen RX can amplify a weak radio signal up to about one million times in a single valve and it does so by simultaneously making use of both analogue (linear) and digital (switching) techniques.
This remarkable circuit was used in British aircraft during the Battle of Britain for the IFF (Identification Friend or Foe) equipment to stop allied aircraft mistakenly shooting each other down in the dark. What's more, IFF was bidirectional, it also had to transmit as well as receive signals--and incredibly it also did the transmitting whilst simultaneously using the very same valve for receiving. Beat that!
In the whole history of electronics, no other circuit has done so much with so few components.