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Low output power from the ADRV9361

Hi,

I'm seeing only -26 dBm output power from the ADRV9361-Z7035 at 6 GHz, and around -15 dBm at 100 MHz.

I'm using a simple GNU Radio FMComms2/3/4 sink with a constant source.

With max hold on the analyser at 6 GHz I get up to -18 dBm during startup, before it falls back to -26 dBm. There is 0 dB TX attenuation applied, and I am using the supplied U.FL to SMA adapter cable.

Thanks,

Alex



Changed Z035 to Z7035
[edited by: AlexJCole at 8:29 AM (GMT 0) on 3 Oct 2019]
Parents
  • Which evaluation board are you using for testing? Can you check the output power at 2.4GHz?  Note that FMCOMMS 2 board is a narrowband board and is optimized in the 2.4-2.5GHz range.

  • What is the power seen at 2.4GHz?  Even though Baluns are wide band there will be some loss at high frequency.

    -26 dBm seems to be very low. there could be something wrong with the U.FL cable , may be not plugged in correctly or some component damage.

    Are you seeing same power across all Tx ?

  • Here is a plot of a wideband sweep taken from an amplifier measurement, so please refer to the blue line.

    I managed to get a 10 dB increase by setting Auto Filter to False in the FMComms2/3/4 sink block in GNU Radio (coincidentally, I'm not sure what that option does).

    There is a 10 dB pad in the chain, so add that value and you get the real values. To answer your question, the output power at 2.4 GHz is approximately -3 dBm.

    The same performance is seen at TX1A and B, whereas both TX2 outputs display a lower frequency null and similar performance below 3 GHz.

    I had assumed this was a result of the board design, but in case there's something I'm missing I'd be grateful for any suggestions.

    Thanks.

Reply
  • Here is a plot of a wideband sweep taken from an amplifier measurement, so please refer to the blue line.

    I managed to get a 10 dB increase by setting Auto Filter to False in the FMComms2/3/4 sink block in GNU Radio (coincidentally, I'm not sure what that option does).

    There is a 10 dB pad in the chain, so add that value and you get the real values. To answer your question, the output power at 2.4 GHz is approximately -3 dBm.

    The same performance is seen at TX1A and B, whereas both TX2 outputs display a lower frequency null and similar performance below 3 GHz.

    I had assumed this was a result of the board design, but in case there's something I'm missing I'd be grateful for any suggestions.

    Thanks.

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