[time-nuts] Effect of EFC noise on phase noise
csteinmetz at yandex.com
Tue Aug 2 04:21:35 EDT 2016
> The preamp will be classical. Some JFETs in parallel * * *
> Cascode with a Zetex bipolar (or whatever they are called now).
> * * *
> Without the cascode, the 1 MHz is not possible. It does not help that
> the feedback limits the voltage excursions on the drain.
As you recognize, these FETs need significant drain-source voltage to
give their promised performance (8v at the absolute minimum, IMO, and
they really should have 10v). You might try a folded cascode topology
(sometimes called a "reverse cascode") to increase the D-S voltage. It
is a little more complicated, but should not have any material impact on
the noise figure if it is done properly.
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