[time-nuts] Re: +1/f of transistors

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On 09.04.22 15:31, Richard (Rick) Karlquist wrote:
> 
> I am seeing a lot of unsupported "theories" about what should be done to 
> make devices with low 1/f noise.  It might be instructive for everyone
> to read Marv Keshner's PhD dissertation (Stanford) discussing 1/f noise.
> He looks at all kinds of theories and shows that there is no valid 
> cookbook for how to make low 1/f noise devices.  It's the classic
> non reproducible process.  I remember an FCS
> talk many years ago that NIST guru Fred Walls gave with some theory
> on how to get low 1/f noise.  Unlike his other papers which were
> well received (and rightly so), this one was rapidly debunked.
> I felt bad for Fred, getting out too far over his skills.
> 
Thanks for the hint towards the thesis, I'll ask our library to fetch a 
copy.

Recently I was discussing some measurement results with my colleagues as 
we're trying to come up with a low noise JFET which can successfully be 
integrated into a SiGe BiCMOS process, and quite often we're also 
struggling to identify why exactly variant A has significantly lower 
noise than variant B, or why a new approach does not improve noise the 
way it was expected.
So from a manufacturing process design point of view, achieving low 1/f 
noise indeed is closer to sheer dumb luck than the proverbial "more art 
than science" suggest.

Florian, DH7FET