Re: op-amp nV input offset voltage

Tom Bruhns wrote:

> Seems like there should be some good references on applying low
> offset, low bias amplifiers.  I know that Bob Pease has had some good
> articles on the trials and tribulations of testing amplifiers down in
> the fA region--not trivial!  His articles can be found with a search
> on the web...
> 
One good set is Jim Williams' 2001 trio of articles on his 1 ppm 
accuracy DAC.  They're on the EDN web site someplace--search on "1 ppm" 
and "20 bit DAC", and they'll come right up.  He even goes into details 
like the thermocouple constant of two different vendors' copper wire: 
+-0.2 uV/K, believe it or not--as big as Cu:Au or Cu:Ag.

Cheers,

Phil Hobbs