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Altera_Forum
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14 years ago

What is free running clock?

Hi i came across the free running clock in the PCI Express Userguide. Based on the words, i thought it is a clock that can run with any frequency. However, in the userguide(page 151), it sta...
Altera_Forum's avatar
Altera_Forum
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14 years ago

generally, a free running clock is not phase locked to other clock sources.

In this case it means you need another oscillator to provide that free running clock mentioned in that altera paper.

"free running" does not tell anything else about additional properties of the clock source, e.g. phase noise performance.