[time-nuts] re low noise regulators
SAIDJACK at aol.com
SAIDJACK at aol.com
Fri Dec 14 17:03:18 EST 2007
In a message dated 12/14/2007 13:51:47 Pacific Standard Time,
bruce.griffiths at xtra.co.nz writes:
>If we assume that in both cases the noise spectrum is flat (i.e white)
>in the 100Hz - 10KHz band
>If we also assume that the noise bandwidth is 10KHz (difficult to know
>more precisely as the details of the band limiting filters used arent
given)
Hi Bruce,
I do believe many regulators have most of their noise in the 1/f band below
100Hz though... which also happens to be the hardest frequency-band to filter
out.
A simple RC filter of say 2 Ohms into 4700uF has a -3dB cut-off at around
17Hz (4700uF caps are getting quite small these days). That would take care of
most of the 100Hz to 10KHz noise.
Using a typical current of 0.16A at 12V for a Euro-can OCXO we would only
have 0.32V voltage drop across the resistor.
I may be mistaken though... BTW: ceramic caps (especially Y5V types) have
pretty bad microphony, so they should be avoided if possible.
bye,
Said
**************************************See AOL's top rated recipes
(http://food.aol.com/top-rated-recipes?NCID=aoltop00030000000004)
More information about the time-nuts
mailing list