Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

PLL output square wave distorted

I am testing PLL output from an old Stratix board. The PLL has an onboard 80MHz crystal as input clock. However at > 60 MHz, the PLL output is not as square as I wish with ripple and 50mv u...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

you did not tell us which scope was used for measurement.

Your scope should have sample rates of at least 2.5 GS/s.

What kind of probes did you use ?

Be aware that the characteristic impedance of the transmission line used on your PCB is important and how it is connected to your chip.