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Old 05-05-2006, 09:03 AM
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Default Re: Phase alignment of DCMs on different boards/devices

> You must distinguish between the relatively long time that th DLL takes
> to achieve lock (many microseconds) and the very small phase error on
> the outputs (picoseconds, which is million times shorter) once the DLL
> is locked
> So, the different DLL will most likely achieve lock at different times,
> but once in lock, they will each perform to data sheet specs, which
> means picoseconds of difference on the outputs

Hi Peter,

I would have thought that if all DCMs start attempting lock at exactly
the same time then they would achieve it at the same time. What causes
them to achieve lock at differnt times assuming the input to each is
exactly in phase and they start working at the same time? Is it down
to differences between the silicon or some other inherent property of
the DCMs loop structures?

Many thanks,


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