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LMX2594: Output power from 10MHz to 3GHz

arun verma
Prodigy 30 points
Part Number: LMX2594
Other Parts Discussed in Thread: LMX2592

We designed our own board using LMX2594 and what we observed that output power at 10MHz is around -40dBm only with 50OHM pull-up resistor. Is this correct output or should we try some other pull-up (Inductor high value)

Arun Verma

  • 0
    TI__Mastermind 28001 points

    Arun,

    -40 dBm is way too low.  This is what would be expected if the output was powered down.  You should be above 0 dBm. 

    Check the OUTA_PWR and OUTA_PD bits (or the other one if you are using output b) and ensure the output is powered up and OUTA_PWR is >10 or so.

    Also, disable the OUT_MUTE bit for debugging purposes.  This bit powers off the output if the PLL is not locked.  This might be good in the final design, but an annoyance if you are trying to debug your design and get your PLL to lock.

    Also, check the lock detect pin where you can use the MUXOUT_LD_SEL to output either a high voltage to indicate the PLL believes it is locked, or read back the lock detect status with the rb_LD_VTUNE word.

    Regards,

    Dean

  • 0 in reply to Dean Banerjee
    Prodigy 30 points
    Hi Dean
    I think I missed one thing in my query. I am getting output power for 3-15 GHz, but for lower frequencies like 10MHz my output power in only -40dBm.

    Arun
  • 0 in reply to arun verma
    TI__Mastermind 28001 points

    Arun,

    This is not expected.  At lower frequency, could this be limited by components?  For instance, if you have an inductor pull-up, or if your AC coupling capacitor for theoutput is too small? 

    Dean

  • 0
    Prodigy 10 points
    Hello arun,
    I am pratik tanwar extc student studying in vidyalankar institute of tech
    Like you even i am developing a board which is based on lmx2592 can we ask for some help to you it would be great if we could get any help from your side please give your contact or mail address to contact you my whatsapp is 9768259207 and email is pratiktnwr@gmail.com
  • 0 in reply to Sagar Kudtarkar
    TI__Mastermind 28001 points
    Arun,
    Thank you for interest in the LMX2592. May I suggest emailing clock_support@list.ti.com