You might start with Leeson's equation to calculate the resonator Q that you need to get the phase noise you desire. Overtone resonators have higher Q, but they are too "stiff" to keep on frequency (with a reactive tuning network) under conditions in which the resonator is exposed to any practical range of (ambient) temperatures. Said another way, to get the phase noise you desire, you may need a Q that can only be achieved with an overtone resonator that cannot be brought/kept on frequency except by keeping its temperature stable (which needs to be above any expected ambient).
There is a lot of good material on this topic at http://www.ieee-uffc.org/publications/books/index.asp If you can afford the complexity and power of synthesizing the desired frequency (with a DDS, perhaps) from the overtone resonator you could absorb the resonator inaccuracy with tuning commands that you send to the DDS. Mike -----Original Message----- From: time-nuts [mailto:[email protected]] On Behalf Of Jim Lux Sent: Wednesday, August 26, 2015 2:24 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] looking for SMT oscillator SC cut, with no oven For a project at work, I'm looking for a good close in phase noise oscillator (better than -100dBc@ 10Hz, -120dBc would be nice) at 100 MHz in a SMT form factor. But it doesn't need good temperature stability. There's tons of SMT OCXOs out there with reasonably good performance, but they draw "watts". My application is actually quite temperature stable already AND I have an external reference to measure against. Most of the lower powered oscillator modules are TCXO, and have, maybe, -80dBc at 10MHz. I guess we could go to a discrete design with a crystal and amplifier, but a little clock module would be a simpler solution. _______________________________________________ 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.
