[time-nuts] Low noise powersupplies

Gerhard Hoffmann dk4xp at arcor.de
Fri Aug 8 06:04:46 EDT 2014

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:


(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 
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 

regards, Gerhard

(holidays in Bretagne, it rains, I wished I had the 89441 here...)

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