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I use another clock for sampling in signaltap II is 576 MHz.
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Ok, so you should see something that looks like a square wave then.
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I did this because first, I want to see if the period and the shape of the two clocks look similar in terms of visualization (normal eyes).
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You won't see that with SignalTap. You need a scope for that sort of visualization.
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And the fact that they looked totally different makes me believe that there exist some problem. And I don't know where it can come from. Do you have an idea?
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Look at the clock output with an oscilloscope. Look at the schematic.
Is the SMA output clock direct from an FPGA pin or does it have a series termination resistor?
Is the SMA input clock direct to an FPGA pin or does it have a buffer between the SMA and the FPGA or does it have a termination resistor? Is it AC coupled or DC coupled? Have you terminated the transmission line correctly, eg., enable a parallel termination if an external one does not exist?
That's a few things for you to think about.
Cheers,
Dave
Honored Contributor
