Quoting "Van Horn, David" <david.vanhorn@backcountryaccess.com>:

>
> Sometimes information seems to be surprisingly hard to come by.
> I'm looking for an NPN transistor, preferably in SOT-23, which has =20
> very low noise at or around 457kHz.
> Bonus points if the base resistance and optimal collector current =20
> are specified.
> My input impedance is low, so FETs are not the optimal choice here.
>
> I've found tons of "low noise" transistors, but frequently this ends =20
> up being in the audio region, and behavior at my frequency of =20
> interest isn't specified.

Ordinary jellybean moderate-power transistors like the 2N4401 are =20
typically low noise- well under 1nV/sqrt(Hz) typical at 1-10mA Ic,.

JFETs like the BF862 are something like 800pV/sqrt(Hz) typical. If you =20
need lower, consider a cascode JFET (or JFET+BJT) configuration and an =20
input transformer.

--sp

--=20
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