rf relay would work On Mon, Mar 8, 2010 at 6:51 PM, Bob Camp <[email protected]> wrote:
> Hi > > Or put another way: > > If you have a structure that uses series resistors and shunt diodes: > > The diodes are reverse biased when the switch is "on". > > The diodes are forward biassed when the switch is "off". > > No current when on = no noise. > > Bob > > > On Mar 8, 2010, at 6:43 PM, Bruce Griffiths wrote: > > > 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? > >> > >> > > Why would flicker noise be a concern if there is no dc current flowing in > the switches? > > > > Bruce > > > > > > _______________________________________________ > > 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. > _______________________________________________ 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.
