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LMX2615-SP: How do I get a 1.5GHz and 0.5GHz clock out at the same time

Part Number: LMX2615-SP

I am trying to figure out if I put a 50MHz clock in can I get a 1.5GHz and 0.5H clock out?  If so, how do I configure the device?

  • Brad,

    Simply stated, you can't.

    There is one VCO divider, so you could do 1.5 GHz and 0.5 GHz, but not at the same time.
    It is possible to have two different frequencies, but the only way for this to be possible is for one of these to be the direct VCO frequency and the other one to be a divided down version on it.

    Regards,
    Dean
  • I see, I can't set the VCO to 1.5GHz and divide by 3 (this does not look like divider option).

    Okay, I have another set of frequencies I would like out. How about set the VCO to 12GHz and have that come out at the same time the device is configured to divide by 32 and get a 0.357GHz output?

    Would this scenario work?
  • Brad,
    This would seem reasonable and you have the right idea.
    However, for this device, above 11.5 GHz, the maximum output divide you can use is 6 in accordance to table 8 in the datasheet.

    Regards,
    Dean
  • Thank you Dean.  This answers my question but does not solve my issue.  I like to have my cake and eat it too. 

    I saw the 11.5GHz limitation in the spec., but I was hoping that I was reading it wrong.  I am not familiar with this device but  think I can still use it by using an external divider in addition to the internal divider.

    VCO = 12GHz (also on an output) + internal divide by 4 = 3GHZ (on the second output + external divide by 8 = 0.375GHz

    Please let me know if I am missing something.

    Thank you again,

    Brad P