That seems to be generally true, but as always there are outliers. The LT1034 bandgap reference has 6uVp-p of low frequency noise at 2.5V, which compares favorably with the 20uVp-p of noise at 6.95V of the LM399. Of course, for many applications, you will have to amplify the 2V reference to what you need, which will bring up additional noise while the 6.95V of the LM399 may be closer to what you need.
Of course, the tempco of the LT1034 does not even get close to that of the LM399, but it is not thermostatically regulated and draws considerably lower power. You can't have everything :) I observe that the LT1034 has two outputs, the high quality 2.5V and a lower quality 7V. http://www.linear.com/parametric/Shunt_Voltage_References Didier KO4BB On Tue, Dec 9, 2014 at 5:51 PM, Richard (Rick) Karlquist < rich...@karlquist.com> wrote: > On 12/9/2014 1:30 PM, ed breya wrote: > > buried zener for lowest noise - this eliminates all the low voltage >> references and three-terminal etc regulators that use band-gap >> references. The down side is that the good kind of reference ICs will >> need a higher (like 10V and up) operating voltage than may be available, >> so that complicates it. >> > > Great post, Ed. I might add that my understanding of band gap > regulators is that they rely on amplifying a small DC difference > in voltage between two transistors. This also amplifies the SUM > of the noise of the respective inputs, which jacks up the noise to > much more than a good zener. Because of physics, no band gap > reference will ever be low noise. > > Rick Karlquist N6RK > > _______________________________________________ > 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.
