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ADF4356 can't locked at desired frequence!

Category: Software
Product Number: ADF4356

It's a custom board. No matter how I change the registers, the output is not working good. I tried bypassing the auto-calibration, but nothing happened. What should I do to make it work?

  • Hi,

    I don't see a major problem here, I tried your REFIN and RFOUT with the EVAL software and it works well.

    my suggestions are :

    1- check the loop filter, I used a 40 kHz loop filter with a good phase margin ( above 45 degrees).
    2- check the sequences, powering and register sequence could be critical, I did not use your ADC frequency but it should be enough.
    3-  use " write int. seq" instead of " write freq. update seq.", when using the EVAL, sometimes the sequence of updating the parameters could cause errors.
    do you always see an unlock for these settings or does it happen sometimes? Have you tried different pfd freq using the same REFIN?

    here are my settings:

    R13: 0xD
    R12: 0x15FC
    R11: 0x61200B
    R10: 0xC00FBA
    R9: 0x100ABCC9
    R8: 0x15596568
    R7: 0x60000E7
    R6: 0x354140F6
    R5: 0x800025
    R4: 0x30028B84
    R3: 0x3
    R2: 0x8F02712
    R1: 0x1134041
    R0: 0x200FC0


  • Thank you very much! I rechecked it and found that there was something wrong with the data I was sending and it worked fine!

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