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Old 10-31-2007, 06:38 PM
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Default Re: Ping Jim: The PFD is dead!

> I "invented" this last week. FPGAs aren't very good at implementing
> the classic charge pump.
>
> http://s2.supload.com/free/PFD.jpg/view/
>
> The outputs here are just hard (not tri-state) logic outputs, driven
> directly by the up/down flipflops in the pfd circuit. It's nicely
> symmetric.
>
> John- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -


But the Inventor mentioned the additional jitter due to uncorrelated
noise of the 2 PFD outputs and their summation in your example, and
the evil glitches due to unmatched symmetry and parasitic coupling of
the digital to the analog !
This must be worth a patent.

Having read

http://www.keystonesemiconductor.com..._releases.html

i now fear the evil glitch and deadtime jitter to corrupt my computer
before global warming blasts icebergs and blazes glaciers.

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