Hi Assuming you are switching between an external reference and the internal OCXO:
The "bleed through" of the OCXO is going to show up as a discrete spur close to the external reference carrier. Unless you have a very unusual architecture, it will be inside the loop for everything you are doing. Attenuating it to a "suitable" level may be quite difficult. Bob On Mar 8, 2010, at 6:34 PM, life speed wrote: > Hello Time Nuts, > > I'm back again. I designed bandwidth-limited (30 MHz) ADA4899-1 opamp > circuits to buffer the 10 MHz reference, with theoretical noise of less than > 3 nV/rtHz. Oscillator noise is about -155 dBc/rtHz from 1 KHz to 10 KHz, and > -160 dBc/rtHz from 10 KHz to 100 KHz. Unfortunately the rest of the design > is holding up PCB manufacture, so results on these won't be available for > awhile. > > Which brings me to the other design-stopping considerations: Is anybody > aware of low-noise analog switches that can be used to reconfigure the 10 MHz > reference paths without significantly degrading the phase noise? As always, > I believe 1/F noise would be the concern. Non-reflective is great, but I can > accomplish that by using more switches and 50 ohm resistors if need be. > Isolation is a key consideration as well. Mechanical relays are out of the > question. > > An alternative to switching is phase-locking the OCXO to an external > reference. I have thoroughly looked into this possibility, and it is likely > my preferred approach. But I need to understand how the switching approach > compares, hence my question. I do not need help with phase-locking; this > feature is readily available from OCXO vendors who have dedicated years of > research to optimizing their products. > > Any switch experience out there? > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
