Forum Discussion
Altera_Forum
Honored Contributor
18 years ago(I'm guessing that you are driving at 1.8V levels on a dedicated clock output).
Have a look at : "Maximum Output Toggle Rate on Cyclone III Devices (MHz)" in here: http://www.altera.com/literature/hb/cyc3/cyc3_ciii52001.pdf (http://www.altera.com/literature/hb/cyc3/cyc3_ciii52001.pdf) You may have to use a higher speed grade.