Linear Technology application note 83 "Performance Verification of Low Noise, Low Dropout Regulators"
holds some interesting information. I am however unsure whether what was low noise in 2000 is still low noise in 2013 Best regards Ulrich Bangert > -----Ursprungliche Nachricht----- > Von: time-nuts-boun...@febo.com > [mailto:time-nuts-boun...@febo.com] Im Auftrag von Bob Camp > Gesendet: Freitag, 1. Februar 2013 13:38 > An: Discussion of precise time and frequency measurement > Betreff: Re: [time-nuts] Low noise power supplies? > > > Hi > > The circuit I described, is (as stated) quiet down to 100 Hz. > It's 3 db bandwidth is well below 10 Hz with the 47 uF cap. > If you need it quiet down to 10 Hz or 0.000000001 Hz, you > will need to buy a few more caps. It's still not rocket science. > > For most OCXO or atomic standard testing applications out > there, 10 Hz is low enough. > > Bob > > On Jan 31, 2013, at 9:41 PM, Charles P. Steinmetz > <charles_steinm...@lavabit.com> wrote: > > > Bob wrote: > > > >> An AD 797, a couple of metal film resistors, and a fairly > large (say > >> 47 uf) plastic cap work pretty well. > > > > The band from 10 Hz down to 0.1 or 0.01 Hz is generally > important when > > testing oscillators. To keep the 797 input noise density > below a few > > nV per root Hz, the terminations must have very low > resistance. With > > such low resistance, a 47 uF cap won't even get you to 10 Hz, much > > less 0.1 or 0.01 Hz. > > > > One more thought: Many oscillators have internal regulators > that are > > not nearly as good as what you can build. No sense using > an external > > supply with 5 nV per root Hz noise density if it will be > re-regulated > > inside the oscillator by a circuit that has a noise density > of 250 nV > > per root Hz. > > > > Best regards, > > > > Charles > > > > > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.