failure in spurious emission test in RX mode with design based on pre-certified modulehttps://devzone.nordicsemi.com/f/nordic-q-a/82447/failure-in-spurious-emission-test-in-rx-mode-with-design-based-on-pre-certified-moduleHi, In our design we use Fanstel BM832 module, based on nRF52832 chip. We have failed spurious emission in ETSI RX mode. Rx LO at ~4958 MHz exceeds the limit by 0.3 dB. I know that it is known issue, described in errata (point 138). I contacted withen-USTelligent Community 13Thu, 09 Dec 2021 11:08:19 GMTRE: failure in spurious emission test in RX mode with design based on pre-certified modulehttps://devzone.nordicsemi.com/thread/342680?ContentTypeID=1Thu, 09 Dec 2021 11:08:19 GMT137ad170-7792-4731-bb38-c0d22fbe4515:8c36e6a0-a218-43b7-8f7f-4d155e98a143nicefor<p>thank you for the great explanation, it seems that we need to redesign PCB...</p> <p>Best regards</p><div style="clear:both;"></div>RE: failure in spurious emission test in RX mode with design based on pre-certified modulehttps://devzone.nordicsemi.com/thread/342357?ContentTypeID=1Tue, 07 Dec 2021 13:56:43 GMT137ad170-7792-4731-bb38-c0d22fbe4515:89cedef0-7efe-40d8-8c6a-f89cc9dd4aa8ketiljo<p>Unfortunately, this won&#39;t work.&nbsp;The VCO that&#39;s generating the LO (local oscillator for the receiver) is internally grounded near pin P0.25. The VCO runs at 2*LO and the ground wire is carrying this signal. The signal is coupled to the nearby bonding wire and radiates from the track that runs from this pin. If you ground the pad by driving it low, you will only do this on the inside of the bonding wire. While the impedance will change when doing this, the 2*LO signal will still couple through to the next bonding wire. Hence you have to decouple this signal on the outside of the chip.&nbsp;</p> <p></p><div style="clear:both;"></div>RE: failure in spurious emission test in RX mode with design based on pre-certified modulehttps://devzone.nordicsemi.com/thread/342238?ContentTypeID=1Tue, 07 Dec 2021 07:43:34 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b3a1adb4-3e1b-495b-8059-5e1448717b64nicefor<p>Hi Ketil</p> <p>Thank you for theanswer. I have one more question, because we simply do not have enough time to change layout before launching device to market - what do you think about configuration of P0.25 and P0.26 as push-pull output and driving it low? May it solve the problem?</p> <p>Best regards,</p> <p>Jakub Kwolek</p><div style="clear:both;"></div>RE: failure in spurious emission test in RX mode with design based on pre-certified modulehttps://devzone.nordicsemi.com/thread/342111?ContentTypeID=1Mon, 06 Dec 2021 14:17:08 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ed1bb99d-4862-441e-b9cd-2820444fae77ketiljo<p>Hi Jakub</p> <p>If the chip inside the module is the QFN packet, QFAA, then P0.25 and P0.26 must be handled properly. I&#39;m surprised that the module doesn&#39;t have the caps on the pins already.</p> <p></p> <p>1. You must either place the caps on the pins or just ground the pins if they are not in use. Make sure it&#39;s grounded as close to the module as possible.&nbsp;</p> <p>2. I guess it depends on how the module was mounted when it was tested the first time. It&#39;s also possible that the test house missed this.&nbsp;</p> <p>3.&nbsp;The errata is valid for all QFAA devices.</p> <p></p> <p>best regards,</p> <p>Ketil Aas-Johansen</p><div style="clear:both;"></div>