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LMX8410L: VCO Calibration

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Replies: 1

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Part Number: LMX8410L

Team, 

I am trying to understand The datasheet for the LMX8410 on the operation of the VCO frequency calibration.  From what I understand, frequency calibration happens as soon as register R0 is written.  Does it calibration the VCO periodically or (in certain condition) does it triggers the VCO to calibrate on its own?  Would be great to get an understanding of the VCO frequency calibration enable bit.

  • Hello Michael,

    Writing a 1 to the recal bit triggers VCO calibration. However, it takes time for VCO calibration to complete and for frequency to be stabilized. This is commonly referred to as "lock time". Once the PLL is locked, the VCO calibration system will stay quiet until another 1 is written to the recal bit.

    Remember that LMX8410L integrates LMX2594 internally, so you can always go to LMX2594 documentation for more information. Basically the VCO calibration will determine three things: VCO core, VCO capcode and VCO amplitude. You can learn more about it starting from page 23 of LMX2594 datasheet.

    Regards,
    Hao