[volt-nuts] The "averaging reference"

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 18 Dec 2014 19:06, "Poul-Henning Kamp" <phk at phk.freebsd.dk> wrote:
>
> --------
> In message <5492F59E.8060808 at free.fr>, Joel Setton writes:
>
> >In my search for the Perfect Volt, I'm thinking about building a
> >reference voltage generator which would average the voltages generated

> If you want to do it "right", you should average all sorts of
> different (but obviously: good) chips, possibly assigning them
> different weight depending on their qualities.

I was aware of  three 8.5 digit multimeters

* Keysight 3458A
* Fluke 8508A
* Keithley 2002.

But

http://www.eevblog.com/forum/testgear/8-5-digit-dmm/

lists several others - some from manufacturers I have never heard of.

I would assume that they all use a state of the art voltage references. I
wonder if they all use the same method?  If not, perhaps averaging those
would be one approach.

How would you average them? Assuming they are supposed to be the same
voltage, would it be OK to tie N output together with N resistors? Use low
value resistors on the references you trust most, and higher values on
those you trust least.

Dave