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Altera_Forum's avatar
Altera_Forum
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17 years ago

Cyclone 3, no output for high freq. signals?

Hi there, I have a design that sends two LVDS signals (one data, one clock) off a cyclone 3 device. When the signal frequency was 250MHz or below, I can see those signals with a scope. But when...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

If you are changing the frequency on the board without changing the frequency for your PLL or altlvds megafunction in Quartus, then you might be exceeding the range at which the PLL can lock with the setting produced during the compile. Recompile with the megafunction set to the same frequency as the board if you haven't already done that.