Hi Magnus, On Sun, 19 Jan 2020 15:56:37 +0100 Magnus Danielson <[email protected]> wrote: > > I also found this common-base amp circuit in the archives: > > https://www.febo.com/pipermail/time-nuts/2016-January/095683.html > > and > > https://www.febo.com/pipermail/time-nuts/attachments/20160126/ae3b4be8/attachment-0001.pdf > > > > I've read that I should avoid high-Q tuned circuits, because they > > will introduce more noise with temperature variation. Are there > > any rules of thumb for how much Q is too much? > > You do not need very high Q, as suitable LCR will fit. Besides, if > there is any of the other overtones creating issues, you can build > LCR links tuned to these that will consume that energy.
Thanks, this makes sense. Any general suggestions for the active device selection, and circuit topology? Is the common-base BJT circuit (in the archive link) a good starting point? > The other fairly obvious solution is as already suggested by Bert is > to use a SiLabs chip. I think Bert was referring to the ICS570 rather the the Si570. The ICS part would completely destroy the sub-picosecond jitter performance of my oscillator (datasheet quotes jitter on the order of 100 ps!), so is not an option. The Si570 family is interesting. I had another look at the jitter / phase-noise specs and it probably would be good enough for an 80-MSPS ADC. However, I have other reasons (longer-term stability) for wanting to use the OCXO. > Regardless if which solution you try, what capability do you have to > test it? It remains an important tool here. There is no golden design > that just solves everything. I've recently measured how very well > performing devices performance was partly lost due to bad design. I > use the old and trusty TimePod. Aha, this is the elephant in the room... I will confess, I was hoping for some rules of thumb that would give me 90% confidence without having to validate the design. (It's a hobby project, so a certain amount of risk-taking is OK.) The only time/freq stuff I have currently are a couple of HP 53310A analyzers and a Trueposition GPSDO. Putting together a DMTD setup would be fun but my project queue is already overflowing :) Regards, Mark _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
