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Original question:

LDC1614: LDC1614 EMI emissions

WEBENCH® Tools/LDC1614: LDC1614 EMI emissions

user5116550
Prodigy 30 points
Part Number: LDC1614

Tool/software: WEBENCH® Design Tools

Hi.

This is Masahiro from Japan.

I asked how to reduce the EMI emission like below.

I was advised to implement common mode choke and shielded cable but I cannot use shielded cable because of its inside size like below.

We measured its EMI emissions and its radiated disturbance is above the reference value of FCC at 600MHz.

How can I reduce EMI emissions at 600MHz without shielded cable??

Thanks.

  • 0
    TI__Genius 17440 points

    Hi Masahiro-san,

    Is the cable the only unshielded part of your system? It's also important to shield the traces and the PCB coil with ground, as well as having a solid ground plane under all other components. Note that the PCB coil should not be shielded with a solid ground plane, but with many ground traces that do not form any closed loops. You can read more about that here: www.ti.com/.../snoa962.pdf.

    In addition, it looks like there is some extra cable length in your system. Is it possible to shorten this? As Luke mentioned in your previous post, worst-case emissions occur when your wire lengths are approaching λ/4 to the antenna measurement frequency, which creates a dipole with the measuring antenna. However, you can see noticeable emissions on these tests with wire lengths as little as λ/16. So at 600MHz, the λ/16 wire length is just over 3cm. In addition to the shielding mentioned above, I would try to minimize cable length as much as possible.

    Regards,