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OPA355: TIA, EMI susceptibility / mitigation

Genius 16285 points
Part Number: OPA355
Other Parts Discussed in Thread: TLV3541, OPA656

Hi all

My customer is using the OPA355 as a TIA. In their application they see issues with EMI.

Can you suggest other OpAmps that might be less susceptible to EMI ?

 .... BW and low input bias current are the main specs the customer cares about ...

Do you have application-level suggestions as to how to mitigate this problem ?

Best regards

Ue

  • Hi Ue,

    What is the minimum bandwidth required by the customer? The two possible mitigation techniques are adding an input filter to reduce interference coupled into the input, and using an EMI shield.

    Best regards,

    Sean
  • Hi Sean

    Thank you for the quick reply. The minimum BW is 170 MHz.

    Are there Application Notes to outline how to implement the input filter ?

    Looking at the portfolio: OPA656 and TLV3541 (EMI hardened) might be alternate candidates to suggest.

    Best regards

    Ue

  • Hi Ue,

    While I was unable to find specific EMI filter application notes, here are two application notes on the subject: http://www.ti.com/lit/an/snoa497b/snoa497b.pdf and http://www.ti.com/lit/an/sboa128a/sboa128a.pdf. The theory is to use a simple RC low pass filter to eliminate the higher EMI frequencies coupled into the amplifier's input. To reduce EMI that couples directly into the amplifier itself, besides using an EMI shield, you can also increase the distance from the EMI source if possible.

    Best regards,

    Sean
  • Hi Sean

    Thank you for these inputs.

    Best regards

    Ue