[volt-nuts] Is there a "standard" much better than a LTZ1000, but much cheaper than a Josephson Junction Array?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 20 October 2016 at 00:08, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> --------
> In message <CANX10hCbbrWvtQhybFf-Pm1uaSyZ3agHLEo8p_5iyoyYR-
> gP8Q at mail.gmail.com>
> , "Dr. David Kirkby (Kirkby Microwave Ltd)" writes:
>
> >The question about the Josephson Junction Array got me thinking. I wonder
> >if there are any sort of technologies that can produce a voltage with much
> >better stability than the LTZ1000, but without the cost of a Josephson
> >Junction Array. A sort of half-way house.
>
> As far as I know there are only two steps between the LTZ1000 and JJAs:
>
> 1. Specially cared for LTZ1000's (See: Fluke)
>

Do you have a specific reference?  A google found lots of kits on Fluke and
LTZ1000,  but none of the pages were from Fluke.


> 2. Lots of LTZ1000's to get sqrt(N) reductions.
>


> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>


But that assumes the drifts are completely uncorrelated, which I doubt is
the case - especially if they are all from the same batch. But there are a
limited number of resistors of the quality needed (Vishay is the only one I
can think of), and PCB materials are likely to be the same. It seems to me
that you would not gain sqrt(N) unless N is quite small. How small, is
anyone's guess.

Dave