Hi How close to frequency is the 10 MHz oscillator?
Is the crystal a fundamental? The degree you can injection lock an oscillator is (as Danna notes) a bit difficult to predict. Your chances improve if the oscillator is low(er) Q. They also improve if it is tuned very close to frequency. Past that it’s a function of power. Also keep in mind that when the GPSDO drops out, you likely will get a “burp” in the output of the injection locked oscillator. That may unlock your PLL. It sounds like the oscillator i this case is not tuned in a normal sense ( = there is nothing to adjust it dead on frequency). First step probably would be to add that “feature” to the circuit. Bob > On Feb 28, 2019, at 6:43 PM, Thomas S. Knutsen <[email protected]> wrote: > > Hello. > > I have a device that consists of a PLL, that has as its reference a > 10MHz crystal. > What I would like to do, is to inject this with 10MHz from a GPSDO, > when that is available, and to use the internal crystal when that is > not available. > > Would it be feasible to just connect it to one leg of the crystal > oscillator with a small capacitor, and with that get injection > locking? > The crystal oscillator is on chip, there is a couple capacitors that > allow for frequecy adjustments, other than that, I know nothing about > what is on the chip. The PLL is SP5769. > > Br. > > Thomas > > -- > With Best regards, Thomas S. Knutsen. > > Please avoid sending me Word or PowerPoint attachments. > > _______________________________________________ > 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. _______________________________________________ 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.
