I am using Modelsim SE 5.8 to simulate cascaded DCMs. I have two DCMs cascaded, the first with CLKIN running at 10Mhz. I am using the CLK2X of the first as the CLKIN for the second DCM. The desired output is CLK2X of the second DCM (I am trying to generate a 40Mhz clock from a 10Mhz clock). When I simulate, I recieve the following warning:
# ** Warning: Timing Violation Error : Input Clock Period Jitter on instance * exceeds 0.001 ns Locked CLKIN Period = 0.1 ns Current CLKIN Period = 0.3 ns # Time: 675 ns Iteration: 2 Instance: /dcmtest224/xlxi_1037
I cannot get the second DCM to lock as well. Any suggestions would be most appreciated.
Best Regards, T. Justin Campbell