[time-nuts] Low noise voltage regulators
bruce.griffiths at xtra.co.nz
Wed Feb 24 22:53:29 UTC 2010
Poul-Henning Kamp wrote:
> In message<4B85A2EB.4000206 at pacific.net>, Brooke Clarke writes:
>> My old Gibbs rack mount 5 MHz standard used the LM723 linear regulator.
>> I believe it's one of the lowest noise regulators you can use.
> If you really want to get low noise, you do the "amplify noise by -1"
> Vicor has a special "afterburner" module you can hook after their
> switchers, which does this.
> The trick is that you don't really need much power in the amplifier,
> it just have to be able to cancel out the noise, a trivial transistor
> or op-amp will do.
> If you really want to go radical, take a peek at Nationals AN1651,
> study the two opamps at the top of the schematics...
The 30uV/rtHz and greater noise (produced by U4 and U5) below 1Hz due to
the 1M series resistor plus the amplified power supply noise for
frequencies below 1Hz or so are a little high for some applications.
More information about the time-nuts