The LTC1655 is a good option if 16 bits are enough. It has an internal reference which is a plus if your oscillator does not have a reference output. The DIP8 package is also a plus for us hand solderers.
The AD5680 is a good 18 bit choice, and a bargain at $9.22 qty 1. It is basically a 16 bit DAC with 2 additional bits via an interpolator, so it needs some filtering at the output. It should be a good choice for applications like GPSDOs where linearity and settling time are not major concerns. One challenge with coarse/fine approaches is that the combined DAC must be monotonic for the loop to be stable. If you can tolerate a reduced automatic tuning range and make the coarse adjustment a manual setting or a setup mode, coarse/fine may be OK. On Mon, Jan 13, 2020 at 7:25 PM Lifespeed <lifesp...@claybuccellato.com> wrote: > I have been looking into all-digital PLL designs to discipline an OCXO, the > scope of which would of course include GPS, as well as other reference > sources. A component of the block diagram would be the DAC converts the > digital control loop output for application to the OCXO tune port. In > order > to use such a circuit to improve Allan deviation, rather than degrade it, > concerns like step size, Differential Non-Linearity (DNL), and possibly to > a > lesser extent voltage noise, are concerns. Some thoughts that have > occurred > to me are coarse and fine DACs, possibly sigma-delta or pulse width > modulation (PWM). Or some combination of all the above. > > Any suggestions on topologies and/or candidate parts? One possibility for > fine tuning might be the AD5791. > > Lifespeed > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > -- --Jim Harman _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.