DCM Simulation : Input Clock Cycle Jitter

Feb 28, 2008 2 Replies

Hi Group,



Just wondering if anyone has seen this issue. I am simulating a Xilinx FPGA design (RTL) containging DCMs. I get the following warning



Warning : Input Clock Cycle Jitter on on instance * exceeds 0.3 ns Previous CLKIN Period = 0 ns Current CLKIN Period = 13.33333 ns



On the face of it, the meaning of this warning should be clear *but* there is definitely no jitter on this input clock. It is driven directly from a testbench. i.e. The warning is completely wrong.



I am using cadence ncsim (mixed VHDL/Verilog). This DCM model is VHDL.



Has anyone seen false messages like this? Did you find a workoround or good explanation.



Thanks,



Steven



Hi Steven, What's the time resolution of your simulation? HTH., Syms.

set the resolution of your simulator to 100ps.

Laurent http//:

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