I might ask the question how much pulling are you looking to do??? Regards On Sat, Mar 5, 2011 at 5:09 AM, J. Forster <j...@quik.com> wrote:
> Capacitively couple a Varactor (or back biased diode) to the circuit and > vary the diode bias to tune. > > -John > > ============ > > > > Hello all: > > I've developed a need for pulling crystal oscillators built in to pll > > circuits. These are cmos, and have the common style oscillator circuit > > built in. The crystal is across an inverter in the chip, and there is a > > small cap between each end of the crystal and ground. > > The chips are pll's in radio transceivers, early at that. > > I could carefully remove the crystals and caps, simply driving the > > non-inverting input on the chip with the reference, but I would rather > > simply tack on a very small cap and "pull" the crystal oscillator with an > > external reference signal of the right frequency. > > Anyone out there tried this? > > Thanks > > Don > > > > > > > > -- > > "Neither the voice of authority nor the weight of reason and argument are > > as significant as experiment, for thence comes quiet to the mind." > > R. Bacon > > "If you don't know what it is, don't poke it." > > Ghost in the Shell > > > > > > Dr. Don Latham AJ7LL > > Six Mile Systems LLP > > 17850 Six Mile Road > > POB 134 > > Huson, MT, 59846 > > VOX 406-626-4304 > > www.lightningforensics.com > > www.sixmilesystems.com > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.