pulsed power with avalanche diode?

[chuckey]

I have heard that when avalanche diode, avalanche they give out a burst of SHF radiation and were the fore runner of the Gunn diode.
I thought that avalanche diode were self protecting as they go short circuit when their reverse voltage was exceeded, hence protecting themselves by not dissipating any power.
Frank
N.B. either the web site has gone mad or my browser has, this is the answer to the questions underneath

 

[newbusofborg]

Can anyone confirm this?

Someone told me that I can run the output of a camera flash through an avalanche diode and the diode will produce a very brief pulse at a much (?) higher voltage and power though possibly burning out the diode in the process. I'm a little doubtful of this. It seems quite possible that you would just burn out the diode immediately without seeing this effect.

Has anyone tried it or care to try it if you have a way to measure it?

 

[newbusofborg]

I heard they act like a zener except where a zener allows current to run and keeps a stable voltage in reverse bias, an avalanche will allow the voltage to run.

 

[jiripolivka]

Avalanche diodes are P/N junction diodes operated in a current-limiting circuit (with a series resistor). Certain models are designed as microwave oscillators (but with a poor noise spectrum), others function as high-power pulse sources (for UWB ), those I used most are nice noise sources, up to 80-90 GHz.
Tell me what you need, I may advise a solution.

 

[betwixt]

An avalanche diode is not the forerunner of the Gunn diode, they work on completely different principles.

Their use to generate fast pulses is similar to the Trappat effect, their 'breakdown' is very fast and in controlled conditions the speed can be used to advantage. By themselves, they do not produce any additional power and would be useless in a camera flash application.

Brian.

 

[jiripolivka]

Still no indication for what you need the avalanche diode.

 

[newbusofborg]

Still no indication for what you need the avalanche diode.

thanks for asking. I don't have a specific end application but I found zener/avalanche effects interesting from the perspective of being a compact source of high voltage/high power even if only briefly. One person told me the peak pulse voltage depends on the voltage of the source (maybe a 50 v source into a 5v breakdown might produce 1000v but a 10v source might produce a much lower peak) another told me that it does not matter what the source voltage is, as long as it is above breakdown and below the peak you will get the same peak voltage. I don't want to burn out any test equipment. It sounds like a fun experiment if someone more experienced than me would like to try it. Actually, it could be that both perspectives are true, one applying to the zener effect and one apply to the avalanche effect, but then which is which?

 

[betwixt]

Think of Zener as being a controlled low voltage avalanche. The junction is doped to deliberately permit the current to start flowing at the desired voltage. An avalanche diode usually runs at higher voltage and the effect is similar to the junction breaking down form excesive voltage. Provided the current is limited to a safe level, the avalanche is not destructive and can be repeated. What is 'special' is the speed at which the breakdown occurs which can be used to advantage when fast edged pulses are needed.

The diode does not produce any voltage whatsoever so person #1 gave you wrong advice. Person #2 is correct but to generate any high voltage (apart from here being much more efficient ways) you have to use the speed of the pulse in a controlled manner, usually a step up transformer. Bear in mind that pulse may only be a few uS long so as a power supply source they are useless.

Brian.

 

[jiripolivka]

Think of Zener as being a controlled low voltage avalanche. The junction is doped to deliberately permit the current to start flowing at the desired voltage. An avalanche diode usually runs at higher voltage and the effect is similar to the junction breaking down form excesive voltage. Provided the current is limited to a safe level, the avalanche is not destructive and can be repeated. What is 'special' is the speed at which the breakdown occurs which can be used to advantage when fast edged pulses are needed.

The diode does not produce any voltage whatsoever so person #1 gave you wrong advice. Person #2 is correct but to generate any high voltage (apart from here being much more efficient ways) you have to use the speed of the pulse in a controlled manner, usually a step up transformer. Bear in mind that pulse may only be a few uS long so as a power supply source they are useless.

Brian.

To my knowledge, Zeners are P/N junctions with doping allowing to "tune" the reverse breakdown at certain voltages. saw 3 V Zeners as well as 67V ones. Some exhibit a "bent" in I/V curve which is used as a negative resistance, to generate noise from several Hz up to ~50 MHz.
Avalanche breakdown can be seen in almost an P/N junctions, and usually destroys the junction. Using a series resistor to limit the current, a diode or a transistor generates noise or pulses of the amplitude corresponding to the breakdown voltage.
Special P/N juctions were made to generate a negative resistance usable up to >100 GHz. The junction should be coupled to a high-Q resonator to generate a "clean" spectrum, still it is noisy.
Another P/N junction type, usually e-b transistor junctions and specials with a "guard ring", have breakdown voltages ranging from 5 to 35 V, and can be used as wideband noise sources, up to ~90 GHz. Spectrum strongly depends on the current, my noise sources of this type are nice and flat with 5 to 15 mA.
For pulse generators try to use ordinary switching transistors with c-e breakdown 50 V, use a large collector resistance like >10 kOhms. With a coaxial-cable section used as a delay line, collector voltage pulses are nice and >50 V upon triggering by e-b voltage pulse.
Many years ago, H-P issued a white paper on avalanche-diode pulse generators, used in their wide-spectrum pulse generators.