Am 08.08.2014 um 02:13 schrieb Alexander Pummer:
people who designing low noise PLLs solved that problem a while ego go
to Charles Wenzels circuit collections he made a very low noise from
DC to a few hundred kHz amplifier just to amplify the phase noise,
here is:
http://www.techlib.com/files/lowamp.pdf
You can also try my preamp:
<http://www.hoffmann-hochfrequenz.de/downloads/lono.pdf >
with some preliminary results on batteries:
<
http://www.hoffmann-hochfrequenz.de/downloads/Noise_Behaviour_Of_Chemical_Batteries_V1.0.pdf
>
(very preliminary, could not get the 89441A to do a multi-decade FFT
from 0.1Hz to 1 MHz, but figured
out how to control it via the network over tcp/ip. Must take multiple
measurements, paste it together
and plot it with gnuplot, takes soo much time to write...)
Since NiCds seem to max out the 220pV/sqrt Hz, I'm also working on a
stereo version of the
preamp so I can use the cross correlation feature to get another 25 dB.
But even now the
thermal noise of 60 Ohm (1nV/sqrtHZ) is consistently in the upper half
of the plots :-)
It will have all controls settable via tcp/ip and bistable relays & a
BeagleBoneBlack.
There a too many possible errors if I try to do it by hand.
Also, my preamp has 1 dB droop at 1 MHz, that's not really flat for my
taste.
regards, Gerhard
(holidays in Bretagne, it rains, I wished I had the 89441 here...)
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