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Feeding PLL

Hi @ all,

is it possible to feed the input of a second PLL (Cyclone EP1C12) with an output clock (for example c0) of the first PLL ?

I mean the two PLLs are positioned in opposed banks.

Or can PLLs only be fed with external clocks on dedicated clock pins?

Thank you for your help.

Rgds André

Reply to
ALuPin
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Hi Andre,

In Cyclone and Cyclone II, the PLL inputs can only be driving by dedicated clock pins. The PLL does provide an external output, so I guess you could route that to the other PLL input on your board.

Regards,

Paul Leventis Altera Corp.

Reply to
Paul Leventis (at home)

I'm far from a wizard on PLLs, but I remember a lot of troubles in the early SONET days.

I think the problem was that the filter on the second PLL let through the noise from the first PLL so the second PLL ended up dancing round much more than you would expect. Maybe it took more than two to cause trouble.

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Reply to
Hal Murray

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