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LMX2595: Phase Detector Frequency in SYNC mode

Johannes Herrmann6
Prodigy 20 points

Part Number: LMX2595

Hi TI-Experts,

I'm using the TICS Pro software to bring two LMX PLLs in a phase synced mode. Since this only seems to be possible for a low phase detector frequency I'm wondering about the reason for this. Is there a way to sync two devices and maintain a Fpd of 200 MHz (why limitations of N divider plus channel divider)?

In our application we would favor a high Fpd within an output frequency range of 10 to 19 GHz. 

Thanks!

  • 0
    TI__Mastermind 28031 points

    Johannes,

    Yes, there is a good reason for this.  Consider the two extremens:

    1.  Synchronize whole divider outside the loop: Problem with this is that the channel divider can go up to 15 GHz, which is too difficult to synchronize.

    2.  Synchronize whole divider inside the loop:  We could have put the whole channel divider in the loop and this would inherently be synchronized, but that would have really reduced the phase detector frequency.  

    So the compromise between these extremes is to put part of the channel divider (4 or 6) in the loop so now now the part of the divider that has to be synchronized is at a manageable frequency where it is easier to do.

    Regards,

    Dean