The tunnel diode is back, as TeraHertz oscillator

Jan Panteltje wrote: ====================

** Always knew the tunnel diode would make it big one day. Was the most talked about semi among young electronics geeks when I was 14 or 15.

Seriously - this could become a huge technology in the next decade. Short range with massive data rate, dirt cheap - make WiFi look silly.

...... Phil

On a sunny day (Fri, 14 Jan 2022 00:44:49 -0800 (PST)) it happened Phil Allison snipped-for-privacy@gmail.com wrote in snipped-for-privacy@googlegroups.com:

My first encounter with a tunnel diode was in the Ampex VR2000 modulators in quadruplex video recorders where it was used to make an FM modulated carrier from say 5 MHz to 6.5 MHz (do not remember the exact frequency but just above analog video bandwidth) recorded to tape. Very reliable stuff, always worked. Small module that replaced the big thing with tubes in the VR1000 models. Bit different from the one I designed and showed with 2 74121 chips with modulated current sources... That worked too :-)

1970 or there about.... lemme see, after the moon landings that was, or more precisely just before studio Vitus burned down... https://www.wikipe.wiki/wiki/nl/Studio_Vituswas re-assigned next morning after the fire to the other TV studios that had those VR2000 recorders. ' I was so much older then, younger than that now' Hey,that was a song : ? / :-)

Indeed. That is quite an impressive trick and small too.

I must take a look. I was researching on them at cryogenic temperatures in the late 1960s and despite the excitement then they did not appear to fulfil their promise...

Brian Josephson not only had a device named after him but was also a chapter heading in a citations journal; double recognition!

When I was working at Plessey Pacific in Melbourne in 1970-1972, our integrated circuit designer was a guy called Mark Schapper who had done his Ph.D. at Melbourne on a scheme to use pairs of tunnel diodes as very high speed bistable memory elements, which a rather higher level obsession.

It was never commercialised, presumably because getting matched pairs of tunnel diodes in production volume wasn't a practical proposition.

The paper talks about using electron beam lithography to get well-defined small structures to generate the terahertz radiation, which isn't exactly a volume production technique either, though a couple of the electron beam microfabricators that Cambridge Instruments sold when I was there were devoted to making very small number of very fast, very small FETs which sold at absurd prices - the acceptance test for one them involved making three four-inch wafers of the devices which - when diced, packaged and sold - would have paid for the million dollar machine.

If it is practical. Tunnel diodes are rather like nuclear fusion - always tomorrow's technology.

That's the dream. There's a lot of engineering left to do to make it work. if it can be made to work predictably in commercial volume.

On a sunny day (Fri, 14 Jan 2022 05:56:13 -0800 (PST)) it happened Anthony William Sloman snipped-for-privacy@ieee.org wrote in snipped-for-privacy@googlegroups.com:

Plenty of tunnel diodes on ebay:

Germanium TDs were cool. I still have a bunch. Some would generate 25 ps steps in the days when a nanosecond was radical. My EE senior paper was "The Tunnel Diode Slideback Sampling Oscilloscope" which I invented, built, and documented the night before it was due. Won some awards, which were a real nuisance.

The TD fabrication process was crazy. A tiny mesh of some metal was thermally smashed into a pellet of germanium, and then etched until just one tiny pillar was left connecting them.

I have the GE Tunnel Diode Manual, 1st edition, 1961, one dollar.

ebay has TDs.

The tunnel diode is, alas, a two-terminal device which can oscillate, mix, and amplify. Optimising ONE of those functions is a challenging design task. In mass production, you can tweak a design then churn out product, like all of the UHF pretuners (back in the days of television transmission bandwidth expansion... half a century back).

My style, though, is more to cobble together a one-off that works reliably... and it's hard to do that with such a nonlinear active component. For that matter, at terahertz frequencies ALL component decisions are hard, except that air is an acceptable insulator. I'm thinking that a pretuned transceiver module would be the only package that would be quick and easy to employ.

Assuming it will be for short range high-bandwidth communication, it has to compete with the burgeoning Bluetooth options. What is the market for that kind of solution? It ain't wireless mice and keyboards.

I recall one superhet where one TD was the RF amp, the local oscillator, the mixer, and the first IF amp.

Yeah, the poor guy got the Nobel Prize for his master's thesis work. That's an even bigger curse than a $100M trust fund.

Of course he went off the deep end almost immediately. :(

What a waste.

Cheers

Phil Hobbs

The Cambridge psychologists saw a lot of him in the 1980's - he got interested in psychology but didn't do anything useful. He wasn't obnoxious or a nuisance, but clearly couldn't get involved in any useful way. Somebody should have worked out what he might be good for and manoeuvred him into that area, but he might have been a bit intractable.