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Altera_Forum
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8 years ago

Cyclone V Fractional PLLs don't output expected clock frequency

I'm using Quartus 17.0.2. I have trying to generate a 148.5MHz clock with a 50MHz input reference clock. When I put the PLL in fractional mode and enter 148.5M as my target frequency the megawizard s...
Altera_Forum's avatar
Altera_Forum
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8 years ago

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There are two options to generate an output clock frequency.

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Yes, the physical parameter options should be used if you are not satisfied with the automatically generated parameters.

The point is that previous Quartus versions, e.g. Quartus 13.1 which I use for existing Cyclone V projects, seem to generate useful fractional parameters automatically. But the reported parameters in your post# 1 suggest, that Quartus 17 generated an integer PLL although a fractional PLL was intended.