[volt-nuts] The 3458A A/D

[Frank Stellmach]

>>"3. The 3458A still has got the best linear A/D, around 0.02ppm of input."

>Is that a typo? Even 0.2 ppm would seem extremely good. I think I saw an
>official number of 0.1ppm somewhere. Probably 0.1ppm of range. And how do
>they implement that? Manual trimming and compensation?

Hello Jan,

well DNL, INL, sometimes I still struggle with those terms..

Those 0.02ppm were nonlinearity of input, measured with a JJ array.
And they use a special multiple slope scheme, with glitch compensation for the switching FETs.

Just download the April 1989 HP Journal, there's everything explained in detail.

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1989-04.pdf


Frank