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Altera_Forum
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13 years ago

Cyclone IV PLL lock range: datasheet vs measurement

Hi, According to the Cyclone IV device datasheet, the: - PFD frequency (Fin/N) should range from 5MHz to 325MHz; - VCO frequency (Fin*M/N) should range from 600MHz to 1300MHz. When...
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Altera_Forum
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13 years ago

You see considerably lower minimal VCO frequency than specified in datasheet. I also observed that the unlocked free running VCO frequency is much lower than the specified minimal frequency. But

- I'm not sure if it's realiably achieved for all devices across process, voltage and temperature variations

- presumed, the actual minimal VCO frequency would be lower, it's obvious that the PLL filter isn't optimized for this frequency range. Higher phase jitter and locking problems may occur.

I'm unable to locate the said 2007 discussion. Any reason why you didn't link it directly in your post?

Regards,

Frank