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Altera_Forum
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15 years ago

Negative slack on TimeQuest report

Hello everybody I'm getting some negative slack messages on TimeQuest Timing Analyzer. I have one input clock and one PLL with one clock output in my system. But all of these messages are r...
Altera_Forum's avatar
Altera_Forum
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15 years ago

Hi cprodrigues,

Probably this happens because you are using the input clock for the synchronizer and then you sample/latch its output with the pll output clk.

You should use the pll clock for the synchronizer, too.

I'm not an expert on this point, but I think that you should use pll in source synchronous mode in order to use both clocks and keep under control their relative phase.

Cris