Re: tunnel diodes retrace lines in curve tracer


 

Hi Rik,

Tunnel (Esaki) diodes rely on quantum tunneling. That is probably beyond the expertise of most electronics engineers to model in the way I think you mean. On the other hand it is not that hard to come up with a polynomial equation that models the shape of the I/V curve of the tunnel diode. I have done this myself. Excel can even automatically calculate a halfway decent polynomial from a spreadsheet you fill with about 20 or 30 I versus V points you plot off of a curve tracer. A really good curve fit requires about 12 or 13 polynomial terms.

The answer to your 2nd question has a lot to do with biasing. With only two leads you are stuck with very simple biasing schemes and options. That severely limits what you can do with a Tunnel Diode and achieve CONSISTENT results. Without consistency it is hard to make reliable products.
When they were first developed their simplicity and their speed were seen as big plusses. When it turned out that simplicity and consistency were not compatible that left their speed as their most interesting features. Gradually over time the semiconductor industry has learned how to make faster and faster semiconductors and that makes TDs less valuable as a circuit component.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of garp66
Sent: Thursday, February 18, 2021 10:59 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] tunnel diodes retrace lines in curve tracer


OT: Fig. 1 of the Tektronix Jack Rogers doc....

Tunnel Diodes and the stock market ??
{ apologies ... really }

I was looking at Fig. 1 in the Jack Rogers doc that Dennis graciously posted,

.. and was immediately struck, ...had just been doing an introductory "Stock Market 101 tutorial" for dummies, the other day,
simply because I know nothing about the market.

The first graph discussed in that SM 101 tutorial was called a "cup and handle" which sort-of looks like the TD Fig.1, in the Rogers Tek doc,
- but the SM graph is reversed along the horizontal axis, compared to the TD graph.

Which brings me to a question that must be obvious, and studied:
-- Have TD's been modelled mathematically in efforts to better understand TD's non-linear behaviour and to produce better units ?
Presumably there are (many ?) EE theses in this area.
and
-- Why have TD's become less of a produced and explored area of semiconductors ?
Is there something that better replaces them now ?

Rik







--
Dennis Tillman W7pF
TekScopes Moderator

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