Re: low-noise sot-23 BJT transistors

On Thu, 02 Aug 2007 05:07:58 -0700, the renowned Winfield
<winfieldhill@xxxxxxxxx> wrote:

Suggestions, anyone?

I've just finished sorting through my collection
of sot-23 BJT small-signal transistors, about
20 types, looking for a low-noise part. The
best I could find was mmbt5089 / pmbt6429,
which have curves showing a lowest e_n of
about 3.5nV. But this is much much worse
than the 0.4 to 0.8nV territory we're used to
with various classic TO-92 low-noise parts.

I am stocking Zetex fmmt618 and fmmt718
(npn - pnp transistors), which are large-die
high-current parts thought to have very low
r_bb' values. I purchased these thanks to
a suggestion by Fred Bartoli here last April.
But these do have rather high capacitance.
Ah, but then again, so do the famed 2sd786
and 2sb737, etc., from the old days.

Some of the DIY audio folks seem to be using 2N4401/3 which are
available in SMT versions (MMBT...). Probably have less capacitance
than those matrix base Zetex parts.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@xxxxxxxxxxxx Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
.

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