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LMX2594: LMX2594 Frequency Drift Spec after PLL Locked

Derek Wang
Intellectual 615 points
Part Number: LMX2594

Hi TI Experts, 

If I do frequency hopping from 4GHz to 4.6GHz.

What is the frequency drift spec after PLL locked?

My system requirement : Frequency drift +/-100Hz at 4.6GHz.

If I use spectrum analyzer to test frequency drift, what RBW frequency I should set to get a correct answer?

  • 0
    TI__Mastermind 27581 points

    Derek,

    As the LMX2594 is locked to a reference, the frequency drift relative to that is 0 Hz.  However, the input reference (not our device) can drift and our part will track that.

    In other words, if you use a 100 MHz input reference and lock our PLL to 4.6 GHz, then the output will always be exactly 46 times the input frequency.  So if the input reference stays exactly at 100 MHz, then the LMX2594 will stay exactly at 4.6 GHz.  However, if the 100 MHz input reference drifts 1 ppm higher in frequency, then the LMX2594 will also follow this and also be 1 ppm higher in frequency.

    Regards,

    Dean