Unusual uses of diodes as microwave and amplifiers

Easy....... One of the simplest and most overlooked oscillators is just a reverse biased diode in parallel with a capacitor being charged up through a resistor to a high enough voltage to cause breakdown of the diode, which discharges the capacitor, the sequence then repeats itself...

A zener or avalanche diode would be similar.

Using a diode at high temperature to allow 'tunneling' is good for high frequencies....

Don't forget these devices such as pin diodes or ..... would you believe I've forgotten the name of my favourite diode!!?

Anyway, these devices can oscillate well into the multi tens of giga Hertz range!!

Also why not remember the humble neon oscillator, same as the diode in parallel with a capacitor connected through a resistor to a high voltage.... Very simple yet effective oscillator...

Or the unijunction transistor.... so many cheap and cheerful devices that don't need an ic to generate noise!!!

P.S. PLEASE don't refer to the years 75 to 80 as ancient.... I was at university in the early 70s and I'm not ancient... No comments please folks

John.

D'oh!!

I was thinking of a tunnel diode of course!!!

John

Electroman,

Can you post this simple schematic along with a few equations for playing around with. Component values and part numbers would be good, too.

Mom said it was OK if you said it was OK.

Whaaaaat you want me to give away all my secrets on a public forum??!!

For nothing!!!!

Okay, when I've found out how to draw and stick things on here I will...

John.

Thanks!!!

Dude! I've been patient! Where are those diagrams!!! ^{Please, please please!!!}

Of course,I have been using in the past,and still sometimes,germanium tunnel diodes such as RTC AEY25,even as backwards microwave detector(as,below the peak voltage of about +200mV,the reverse conduction is higher than the forward conduction)and General Electric TD263 to TD265.
However,they are very expensive in France:300$ for a single General Electric TD26X,half the price from the second source Germanium Power Devices,which is still 150$.Power germanium tunnel diodes oscillating under 400mV have been used in the sixties for electric power generation in submarines using magnesium-sea water batteries as primary source.
I also know and use Impatt and Gunn diodes at microwaves(12 to 95GHz),but the price of such diodes and millimetric plumbery is in the thousands of dollars range.

That's why I am also interested in generating µwaves with dollar range components.

I acknowledge one of the replies to that question on unusual operation of diodes under second breakdown.

Indeed,it may exist tens of thousands of papers written on these subjects since the beginning of the 20th century.
For example,this morning,I read at the University of Paris XI at Orsay the Pascal treatise of chemistry on lead sulphide:samples from a mine in the United states were found to have a suitable doping profile for use as a transistor.
Nowadays,one design inkjet printable organic leds,and serigraphied thick films field effect transistors are already in use.There must exist thousands of sorts of organic and inorganic printable semiconductors,tens of which should be of practical application to,for example,the future E-paper,the fully electronic thick or thin film newspaper.

Someone asked wether one could give some ordinary mathematics in the subject:

Consider this.A silicon device with a very low doping level, in the range 1E15/cm3,has a mean distance between doping traps in the 100 nm.

I should add further that nm is to mean nanometer, 1E-9 meter

and not nautic mile, 1852 meters, as in the CIA report on the world, which I found very interesting, both on my country, France, and that of my new wife, Madagascar.

Indeed, as the forbidden gap for silicon is about 1,2 eV, it implies that intrinsic silicon sustains 1200 Volts / 100µm, what it does indeed,in ordinary low cost MOSFETs and IGBTs.

I found a paper on the special doping profile of G3M rectifiers, used as pulse strechers:

a G3M converts a 3ns rise time pulse of 1,2kV to 200 ps rise time.

Suppose now that, instead of 1E15/cm3, you have a higher doping level, of 1E18/cm3.
You should observe tunneling between doping traps, whose distance is of the order of the De Broglie wavelength of charge carrier.
I shall try to use the dispersion relation (in k space) of charge carriers to find the analytical expression for a tunnel diode, which should be a 3rd order polynomial.
Other curious operations of diodes could be found with such reasoning.