Higher Output Switching Frequency

[Leonard Chan]

Hello I am hoping to output a 225MHz clock on either a Basys3 or Zybo board. I can generate the necessary clock speeds internally however the hardware has settling times which appear in the range of 10ns instead of my desired 2ns, which when reading the spec sheets most settling times are significantly less but I think the hardware outputs are larger. I initially receive a warning about trying to connect a circuit routed to clock with the hardware pins which is likely the cause. Through reading I found the Zybo had high frequency PMOD pins however these showed no improvement in testing. In further reading I was told only pins that ended with SS were capable of being used as clock outputs however these pins also showed no improvement.

 

I was hoping someone could suggest a way to output my desired clock frequency. I feel like there is some hardware specification I have to make but I can find nothing on the subject. Thank you for any insight. 

[D@n]

Are you using the Xilinx ODDR primitive?  You may also find the ODDRSERDESE2 to be valuable.  Xilinx recommends using the ODDR primitive in order to output a clock.

Dan