[time-nuts] pulling oscillators

[Adrian]

Don,

if you have a reference oscillator of the right frequency, what's the 
the purpose of trying to pull a CMOS oscillator to the same frequency, 
rather than just using the reference frequency?
Please be more specific on whant your requirements are.

Adrian

Don Latham schrieb:
> 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
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