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Altera_Forum's avatar
Altera_Forum
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13 years ago

How to see the true clock period in TimeQuest?

In some design, I will use the output of counter to make a clock signal if the demand for clock period is not very strict. In sdc file, I can use comand: create_generated_clock divide_by ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

A digital counter divides the clock *exaclty*. There's no error.

If you have a 40 ns clock and use counter of 256, you get a clock with 10240 ns period exactly.

If you have a 40.0001 ns clock, you get a clock with 10240.0256 ns period exactly.

The input clock may and will have fluctuations that will affect the generated clock.

The generated clock will also have higher jitter.

But period wise, the divider has zero error.