Forum Discussion
New ContributorJitter performance due to non-dedicated routing?!
I'm only assuming the "two issues" are true for your design. Without knowing more of your device/pinout I can't comment.
Regardless of that, I'd change it to use a single PLL using two clock outputs, ensuring you use the appropriate FPGA pin, associated with the right PLL, for ADC_CLK.
Cheers,
Alex
ContributorI assume the your chosen pin for the ADC_CLK signal is the correct PLL_CLKOUT pin for the PLL in question...
Assuming so, I suspect the clk[0] port on the PLL feeds other logic, as well the the FPGA pin. If this is the case you'll get this warning. In order for the dedicated routing to be used the PLL output must only feed the FPGA pin.
Assuming you have one, use another PLL output configured with the same settings as the ADC clock, to feed your internal logic.
Cheers,
Alex
NorickAccording to your answer, I think there are two issues to this PLL:
- The PLL_CLKOUT goes to the ADC_CLK Pin as well as to other logic
- ADC_CLK Pin is NOT the dedicated PLL output pin
Question:
- Is it better to use a PLL with two outputs with
- c0: ADC_CLK
- c1: internal logic
- Or two use two independend PLL's?
best regards
