4 Replies Latest reply on Oct 8, 2018 6:24 PM by stlic_2591831

    PSoC 4 BLE EMC Problem

    stlic_2591831

      I use CY8C4247LQI-BL483 to work at any time, the 4.9GHz signal that can be measured in the ANT pin, the current safety certification does not pass, is there any setting for the software to turn off this signal?

      The 4.9GHZ spectrum picture is linked as follows

      http://imgbox.com/G55sAxPg

      http://imgbox.com/hvt2CedA

        • 1. Re: PSoC 4 BLE EMC Problem
          GuhapriyanT_31

          Hi gck059_2591831,

           

          I am not aware of a software work around for this issue. Can you post a snapshot of the matching network you have for the radio and the Antenna? Having a low pass matching network (with series L and shunt C) reduces the spurious very much.

           

          Thanks,

          Guha

          • 2. Re: PSoC 4 BLE EMC Problem
            stlic_2591831

            Hi Guha,

             

            Thank you for your reply

            My circuit does not have a low pass filter circuit only the antenna matching,

            Now that the product is in volume production, I want to know if there are other ways to improve this issue apart from modifying the PCB circuit.

            Schematic

            http://imgbox.com/3BZE1Hm7

            Layout

            http://imgbox.com/7Kbe3047

             

            Thank you again

            • 3. Re: PSoC 4 BLE EMC Problem
              GuhapriyanT_31

              Hi gck059_2591831,

               

              The 6.8 nH shunt, 1.5 pF in series followed by 1.2 pF shunt you have after the ANT pin is actually meant for PSoC4 BLE radio. This is something that you could alter to get it matching with a low pass components.

              We have experimented with a firmware workaround for reducing this spurious during the product validation. We got a setting that reduced the spur by 6 dB. But taking up this setting means a full round of characterization (of testing all the parameters across temperature, voltage and process corners on tens of device and ensure that all the other parameters are still intact. The easier solution was to contain in through the matching networks (of the radio and optionally the antenna too).

               

              Can you try the following modification.

               

              Replace L1 with 1 pF

              Replace  C31 with 3.3 nH

              Replace C32 with 1.5 pF

               

              Thanks,

              Guha

              • 4. Re: PSoC 4 BLE EMC Problem
                stlic_2591831

                Thank you for your guidelines, I will modify it according to your suggestion,

                Thank you very much.