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LMX2595: Phase coherence

Callum Austin
Prodigy 140 points
Part Number: LMX2595

Hi, could anyone tell me how to get my LMX2595 to be phase coherent with an external synth using the 10MHz reference? 

I tried putting the 10MHz reference as the OSCin, so my PFD was 10MHz but not sure if thats working.

Any help would be appreciated.

  • 0
    TI__Guru* 81580 points

    Hi Callum,

    Did you mean the external synth and LMX2595 share the same 10MHz reference?

    The function of phase synchronization in LMX2595 is to align the phase between its output and input. If your use case configuration puts the LMX2595 in Cat.1, Cat.2 or Cat.3 sync, phase synchronization is possible. 

    If you have the 10MHz reference shared, and if the external synth can also phase align its output and input, then both synthesizers will be phase aligned.

  • 0 in reply to Noel Fung
    Prodigy 140 points

    Hi Noel thanks for replying. 

    I have an external synthesizer which can input/output a 10MHz reference for phase coherence. The external synth is set to output the same frequency as my LMX2595 synth. If I wanted to make the two synthesizers phase align how would I go about doing that? Is it through the SYNC pin or can I just use the 10MHz reference as my reference oscillator to the LMX2595 synth? 

    Many thanks

  • 0 in reply to Callum Austin
    TI__Guru* 81580 points

    Hi Callum,

    Use the flow chart in Figure 27 of the datasheet to determine the sync category and the corresponding method to achieve sync. For example, in Cat.1 sync, you don't need the SYNC signal at all.