Re: Low noise IF3601/02 don't meet specs

Top post corrected for clarity.

"Joe G (Home)" <joe.g@xxxxxxxxxxxxxxx> a écrit dans le message de
news:43b55d60$0$18200$afc38c87@xxxxxxxxxxxxxxxxxxxxxxx

> "Fred Bartoli"
> <fred._canxxxel_this_bartoli@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
> message news:43b558ab$0$21719$626a54ce@xxxxxxxxxxxxxxx
> > I've finally got to test some of those huge Interfet jfets for their
> > noise.
> > Impressive, but...
> > they are spec'd at 300pV/rtHz @ 5mA and 100Hz and should get down near
> > 260pV
> > @ 100kHz.
> >
> > Well for the IF3601 and both side of the IF3602 dual, I get 400pV/rtHz @
> > 5mA, and the noise PSD is almost flat.
> >
> > I have to rise Id to 20mA (x4) to get almost the low Id noise specs (get
> > 290pV/rtHz at 100kHz).
> >
> > Before I get some other parts, I'd like to know if someone managed to
> > obtain
> > the figures they claim.
> >
> > Both samples have the same date code, so it might be just a bad process
> > issue... or not.
> >
> >
> > --
> > Thanks,
> > Fred.
> >
> >
>
> In the old days - silicon manufacturers used to publish the test setups to
> acheive the data *** spec's.
>
> These days there is less information on how the data *** values are
> acheived.
>
> Some times the only hint from the data *** is the "recommend values"
(not
> limits).
>
> If you have some weight..... (meaning.... you are going to purchase
> significat volumes) you can lean on the distributors of the InterFET or
> InterFET themselves
> to get info on how the results are acheived.... No weight (no $$$ ) may
> mean no support.
>
>
> You can't say the FET doesn't meet spec's until you repoduce the mfg'ers
> test setup... and even then they may have something special which helps
> reduce the noise during testing - that is not documented.
>
>

Of course I can. I duplicate the working conditions of the data***
(5mA/3V) in a test setup that's designed to add not more than 2% to the
measured noise. Not a big deal really.
If the final result is out by a 4/3 factor I can tell the part is out by a
4/3 factor, at least. Interfet's test setup surely won't substract noise
so... either the parts are off, or the data*** is off, or their setup
doesn't measure the full noise which I translate to a case of wrong
data***.

But we're not there now. I was just asking if someone managed to get the
speced figures.



> Regards
> JG
>
> Hmmm the front page of their data books says
>
> InterFET is big enough to competitively supply over 400 standard
>
> JFET types. Small enough to craft JFETs to your exact specifications.
>
> Big enough to supply national and international leading-edge electronic
>
> manufacturers and laboratories. Small enough for you to talk directly
>
> with the people that engineer and manufacture the product.
>
> Every business has a culture, a way of doing business. Ours isÉ
>
> How we serve each customer is more important than how many
>
> customers we serve.
>

Yes, that's what they wrote and what it seemed at first contact. Then I'm
still waiting answers for some questions I asked a while ago.
I had not much time to reactivate them, so we'll see... but I'm still
waiting.


--
Thanks,
Fred.


.

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