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LMX2594EVM: Low single ended power output from evaluation board

Stuart Rumley
Prodigy 250 points
Part Number: LMX2594EVM


I have just received a new LMX2594EVM and am generally satisfied with the performance expect for the output power.   The data sheet for the part, Single-ended 50ohm pull-up is suppose to be +5dBm at 8GHz and +2dBm at 15GHz..  My board produced +4dBm at 8GHz and -4dBm at 15GHz.  I've cross check these reading with a spectrum analyzer and a power meter and get good agreement.  The connection is direct, just a barrel adapter no cable.  Can someone tell me what the expect power at these two frequencies should be on the EVM? 

  • 0
    TI__Expert 5370 points
    Dear Romley,

    I am glad you are satisfied with the device.

    The output power reported in the D/S includes some de-embedding (trace loss and matching with manual Maury tuner) and hence what you read out from the EVM with be different. The difference is also bigger at the top end of the frequency range of 15 GHz.

    I just verified the output power at 8 and 15 GHz with a random EVM. I used the power meter capability of the 5053 and got the following results connecting the EVM with a male2male sma connector. They align well with your measurements:

    5053 power measurements with male2male single ended output and 50 ohm termination on unused port. I also leave the output power setting to 31.
    8GHz -> 5.4 dBm
    15GHz -> -3.3 dBm

    I hope this answer your question. Let me know if you have other questions.

    Regards, Simon.
  • 0 in reply to Simon Damphousse
    Prodigy 250 points
    Okay that agrees with what I read but my power setting was at max (63).

    8GHz -> +5.4dBm me-> +4dBm
    14GHz -3.3dBm me -> -4dBM

    Thanks for the reply.
    Stuart Rumley
  • 0 in reply to Stuart Rumley
    TI__Expert 5370 points
    Dear Rumley, little difference beetwen 31 and 63. You have the correct measurements, regards, Simon.