[time-nuts] +1/f of transistors

[Leon Pavlovic]

Hello to all,

as Gerhard already mentioned, the 1/f data of transistors is really a
kind-of black magic stuff and almost never present in the datasheets.

But it is very important for the designer of the ultra low-PN crystal
oscillators and isolation amplifiers. Manufacturers like Wenzel and others
keep this info as a top secret I can imagine.

For the MMICs, Mini Circuits has done a recent publication where 1/f noise
has been evaluated.

But maybe we can assemble a list of verified transistors that have low
noise performance.

Dr. Rohde always used ex CEL NExxxxx series for his designs, but those are
long obsolete. What about Siemens/Infineon BFR/BFG and other series? AF and
KF SPICE parameters are almost never given by the manufacturers. A general
rule is use a BJT with Ic-max of about 100mA and use it at 10mA.

Well, some audio experimenters have chosen and measured ZETEX ZTXxxx parts
as very low noise BJTs, but those are usable only up to about 50MHz.

It's a very interesting topic for me. Have done some oscillators designs
and also low noise amplifiers, but a better solution (lower PN) is always
wanted and required ;)

Cheers,
Leon