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AMC3330-Q1: Several noise peak in sub 1GHz

Masaru Oinaga
Expert 3615 points
Part Number: AMC3330-Q1

Tool/software:

Hello, Team,

Our customer observed some relatively-noticeable noise (dark noise +10dB) after a noise evaluation on AMC3330-Q1 on their board. This matches with the TI application note so they think that it is coming from AMC3330-Q1. It does not look like a multiplied version of the switching frequency (i.e. 30MHz.) Could you please let us know what might be causing this? 

There was only a slight change of ~2dB when they inserted a ferrite beads (BLM15HD182BH1) on the high-side input. In addition, no effect when ferrite core is inserted on the high-side bus bar. Therefore, they think that the noise is coming from the low-side.

*RED circle is where they inserted ferrite beads.

Customer's evaluation:

Appnote:

Best,
Masaru Oinaga

  • +1
    TI__Guru 53672 points

    Hi Oinaga-san,

    What are the different curves in the customer evaluation picture you posted? 

    The application note only focuses on the variation of the input traces lengths or high side, but the design of the low side will also impact as it makes up the other half of the dipole antenna. 

    The customer could consider adding ferrites beads to the low side, perhaps VDD and GND depending on connections to verify. 

    If the customer can provide a schematic and layout that would allow for better assistance. 

    Can you please comment on who the customer is? 

    Please feel free to contact me offline if it would be more appropriate. 

  • 0 in reply to Alexander Smith
    TI__Expert 3615 points

    Hello, Alex,

    Let me bring this to offline conversation.

    Best,
    Masaru