As I said in my original post from our point of view there are only two reasons for a Rb time and 16 bits will do the job. I would not do an OCXO with less than 22 bits if analog at all. Bert Kehren In a message dated 11/26/2017 8:56:51 A.M. Eastern Standard Time, opronningen@gmail.com writes: I guess everyone has seen this, but Linear has a nice appnote «A Standards Lab Grade 20-Bit DAC with 0.1ppm/°C Drift» http://cds.linear.com/docs/en/application-note/an86f.pdf Ole > 26. nov. 2017 kl. 13:50 skrev Magnus Danielson <magnus@rubidium.dyndns.org>: > > Hi > >> On 11/26/2017 02:26 PM, Attila Kinali wrote: >> Though, if you have a decent 16bit DAC and want to get to 18bit, >> that's fairly simple using delta-sigma modulation... if you can live >> with a low pass fillter after the DAC. But the DNL will be the limiting >> factor here (unless you use some special techniques) and the (absolute) INL >> will not get better, for obvious reasons. > > I needed 19 bit rather than 16 bit, so I implemented an interpolation scheme. A first degree sigma-delta would also be possible, but for low ratios what I did was more efficient. > > A first degree sigma-delta is fairly simple thought. > > The trick is that you want to push the noise high up so it becomes trivial to filter, then the filter will not be hard to design and won't be low enough to cause PLL instability and implementation troubles. > > Cheers, > Magnus > _______________________________________________ > 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.