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  • Case ID: 355069
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nRF52832-CIAA-G-R7 Rx Sensitivity

Star.Tong

Hi There,

During the transmission and reception performance test, I found that the LE1M's maximum sensitivity was only -92 dBm, while the LE2M's maximum sensitivity was only -89 dBm. These values were measured using the IQ and added pathloss. The data do not match sensitivity of -96dBm in datasheet. Could you please confirm whether the configuration mode for SDK 2.6.1 is nRF mode?

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  • 0
    Hello Star Tong,
    Regarding the sensitivity, it comes down to layout and implementation as well. So what sort of HW did you run the test on? Are you able to compare performance with a nRF52832 DK?
    The results we have reported in the product specification come from performance on boards using the reference schematic and layout with an ideal transmitter. It's optimum conditions, but this is what we would expect to see customers getting close to as well with a reference schematic and layout.
    ---------------------------------------
    I don't understand what you are asking here:
    "Could you please confirm whether the configuration mode for SDK 2.6.1 is nRF mode?"
    May I ask you to elaborate  what you mean by this?
    Best regards
    Asbjørn
  • 0 in reply to Asbjørn

    Hi Asbjørn,

    Thank you for your reply.

    I tested on my own custom-designed product board.

    Regarding the layout issues you mentioned, I have the following additional comments from a hardware perspective:

    1. I verified the Tx performance aligns with the link budget, so sensitivity degradation due to mismatch can be ruled out.

    2. If the issue stemmed from desensitization, the 3dB degradation observed at LE2M compared to the datasheet would imply over 6dB degradation at LE1M—not just another 3dB. Currently, the 3dB sensitivity difference between LE1M and LE2M aligns with theoretical calculations.

    3. I noticed the following statement in the datasheet:

    'Typical sensitivity applies when ADDR0 is used for receiver address correlation. When ADDR[1...7] are used for receiver address correlation, the typical sensitivity for this mode is degraded by 3dB.'

    Therefore, I request your assistance in verifying whether any errors exist in the register configuration at the software level.

    Best Regard.

    Star.Tong

  • 0 in reply to Asbjørn

    Hi Asbjørn,

    The custom circuit board I'm using

    When Tx setting is 4, I measure 3.5dBm at the antenna end, corresponding to 4.1dBm at the chip output, with very flat in-band power.

    I've measured PWR, Frequency error, ACP, ect... all of them are fine.

    Best Regards.

    Star

  • 0 in reply to Star.Tong
    Hello Star.Tong,
    From what you are writing, the output power seems to be ok as you say.
    ------------------------------------------
    There are still aspects related to your custom board that can affect this, like noise on the power supply, frequency accuracy and connections made, packet length, BLE mode or nRF mode. I don't know these aspects so it is difficult to point at what is causing the difference between the expected -96dBm and the measured -92dBm in 1M BLE mode. https://docs.nordicsemi.com/bundle/ps_nrf52832/page/radio.html#d939e34725
    ------------------------------------------
    We do run all our chips through production testing and they need to show the same performance. In theory the output power between chips are the same, but majority will range with +/-2dBm from specification and some outlier could go out to +/-3dBm, but it would be unrealistically unlikely that you would have several of these outliers on all of your boards. 
    ------------------------------------------
    I don't have all the information in this case, so at this point it is not possible to know or explain the findings. We can help you onwards, but it would require more information about the board and FW you are using. Have you tried comparing the performance with a nRF52832 DK?
    Best regards
    Asbjørn
  • 0 in reply to Asbjørn

    Hi Asbjørn,

    I ran a SA check today and found that a spur appears at the ANT port when in receive mode, and varies with changes in channel settings.

    What do you think caused this?

    We've encountered similar issues on other chips and resolved them by modifying the firmware. Do you have any recommended solutions?

    Best Regards.

    Star

  • 0 in reply to Star.Tong

    Hello Star.Tong,

    with the screen shot I assume you have configured the device to in receive mode 1Mbit at frequency 2440?

    The spur you are observing is the receive local oscillator. It can be seen as RXLO = frequency-1MHz (for 1Mbit mode) and 2xRXLO.

    Best regards

    Asbjørn

  • 0 in reply to Asbjørn

    Hi Asbjørn,

    Thank you for your reply!

    Correct. I set the mode to LE1M. Is there a solution for this issue?

    Best Regards.

    Star

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