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Altera_Forum
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18 years ago

connect 2 PLLs in cyclone II

Hi all! I create a project in cycloneII 35. I must use 2 PLLs from 1 external clock. So, I must connect them. But when I do this, there're many problems. For examples, when compiling there's error...
Altera_Forum's avatar
Altera_Forum
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18 years ago

As said, Cyclone II doesn't support chaining of PLLs as you can do e. g. with Cyclone III.

For this reason, I usually routed the main clock input "all around" the FPGA in Cyclone II designs. If you need a PLL function without strict timing requirements, you can probably output it to a pin next a dedicated clock input and route it through pins. A routing delay could be compensated by PLL phase shift.