There is now a first draft of the 'DDS-board', a 4-layer 100mm x 100mm PCB with an ADF4351 PLL+VCO, and two AD9912 DDSs over here: https://ohwr.org/project/microstepper/wikis/2020-06-02-DDSboard-draft (kicad sources in the repository at https://ohwr.org/project/microstepper/tree/master/ddsboard)
I will order a few prototype PCBs in a few weeks. In the meantime if anyone has comments/suggests on the schematic or PCB from previous experience with ADF4351, AD9912, or similar ICs then please let me know. This DDS-board might be useful for other time/frequency tinkering also, in addition to being a part of the second microstepper prototype I will try to build within 1-3 months. regards, Anders On Tue, Jan 14, 2020 at 8:58 AM Anders Wallin <anders.e.e.wal...@gmail.com> wrote: > > prototype block-diagram, short list of chips in the implementation, and a > discussion on resolution now on ohwr.org: > https://ohwr.org/project/microstepper/wikis/Block-diagram > > The obvious way to increase resolution (make the smallest frequency step > smaller) is to lower the IF. > I guess the limit is that we don't want the IF to feed-thru the > phase-detector and PLL all the way to a PN-spur in the output-OCXO. > My first prototype used 97 kHz IF and that gives a resolution of 1.7e-17. > Lowering that by /2 or /4 might be a good idea? > Other comments and ideas welcome! > > Anders > > >> my plan is to present our DIY version of this, an open hardware design, >> at EFTF2020. >> we have two AD9912:s clocked at 1GHz (derived from the maser) producing >> two LO's that drive a mixer-board that locks an OCXO that feeds a PICDIV. >> >>> >>> _______________________________________________ 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.