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PLL used for differential interference analysis

I have a question about PLL.
Currently I am performing differential interference analysis using signal generators from other companies, but there is a problem.
The sign of the phase is changed by turning on / off the power supply.
My question is
· Is it possible to control the initial phase and phase sign (positive Θ or negative Θ) when TI PLL locks the phase?
· If possible, is it possible by register manipulation of the IC or is it necessary for external circuit?
Waiting for your answer.

Best Regerds

  • Hello,

    Can you tell me what the TI part no. is for the device in question?

    Best Regards,

    Jeff Pfarr

    Texas Instruments

    Online Systems Support - Analog

  • In reply to Jeffery Pfarr:

    Hello, Mr Jeffery Pfarr

    Thank you for your replay.

    I am sorry that there is little information given to you.

    I'd like to use the LMX 2492.

    Can the LMX 2492 solve my problem?

    Best Regards,
  • In reply to user4905227:

    Hello, I'm going to refer you to an Apps. Engineer that is responsible for this device.

    Best Regards,

    Jeff Pfarr

    Texas Instruments

    Online Systems Support - Analog

  • In reply to Jeffery Pfarr:

    Hello, Mr Jeffery Pfarr.

    Thank you for your replay.

    I appreciate what you did.

    I am waiting for the message again.

    Best Regards,
  • In reply to Jeffery Pfarr:

    Hi There,

    For a simple PLL, the output of the VCO will be phase aligned with the reference clock.
    With LMX2492, the VCO output will also be phase aligned with the reference clock, maybe with some little delay created by the PFD_DLY register setting. PFD_DLY is intentionally added to the phase detector in order to reduce spurs.
  • In reply to Noel Fung:

    Thank you for your reply.


    PFD_DLY register adjusts the timing of lock by adjusting pulse width of Charge pump.
    What I want to control is the direction of phase advance.
    (I drew a figure in the attached file)

    The phase at the start of Charp can be arbitrary, but I want to fix the direction in which the phase advances.

    Is it possible to fix the direction in which the phase advances with the LMX 2492?

    Also, if it is not possible with an IC, is it possible to control the phase with an external circuit?

    phase timing chart.pdfWe will be wqqqaiting for your reply

     

  • In reply to user4905227:

    Hi,

    is this something you are looking for? I don't think we have control on the phase.

  • In reply to Noel Fung:

    Hello, Mr Jeffery Pfarr.

    Thank you for your replay.

    I am terribly sorry for the delay in contacting you.


    It will be the last question.

    Is it possible to adjust the phase at the beginning of Charp?

    Looking at the Phase graph, the Phase at the beginning of Charp is irregular.

    Is there a way to make Phase constant?

    Best Regards.

  • In reply to user4905227:

    Hi there,

    I am afraid we don't have control to the phase.
  • In reply to Noel Fung:

    Hello, Mr Jeffery Pfarr.

    Thank you for your replay.

    Are you still so....

    If you know how to control the phase with another PLL IC or DDS etc..., please let me know.

    Thank you for explaining so politely and thoroughly.

    Thank you!

    Best Regards