[time-nuts] DMTD - analog multiplier vs. diode mixer ?
attila at kinali.ch
Thu Jan 7 12:35:55 UTC 2016
On Wed, 6 Jan 2016 18:30:07 -0800
"Richard (Rick) Karlquist" <richard at karlquist.com> wrote:
> Read Gilbert's paper or Gray and Meyers analog IC textbook and
> you will see that the whole theory of operation of these
> depends on keeping the signal levels in them very small,
> especially if linearity (actually translinearity) is
> important. They always have current sources in the
> emitters that contribute a lot of noise. So you have
> small signals and large noise. The IC's that are
> designed to be DC coupled have even more sources of
> extra noise.
How about using the Gilbert Cell as "digital" mixer,
ie driving the currents hard from one branch to the other
and replacing the current sources by resistors?
How much would that improve the noise? Would it be still much
worse than the diode mixer?
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
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