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OPA320: Noise improvement

Isao Takigasaki
Intellectual 2530 points
Part Number: OPA320

Hi,

My customer evaluated noise test with OPA320 on their production board.  As the result, they found slightly higher noise than theri internal regulation.
Could you advise them to solve it.  Schematic and layout will be sent by email.  PLS check it.

Your cooperation will be appreciated.
Best Regards, Taki

  • 0
    TI__Genius 11135 points
    Isao

    Since this is being handled via internal email I'm going to close this thread.

    Thanks
    Dennis
  • 0
    TI__Guru 60610 points
    Takigasaki-san,

    It is not clear to me from the description below whether the noise customer sees is an intrinsic noise (internal to the circuit) or extrinsic, EMI/RFI, type of noise coming from the outside environment?
    Increasing C524 decoupling cap to 10uF only lowers the EMI/RFI pick up and noise coming from the supply source but does not do anything to lower the intrinsic noise; thus, one way to improve the circuit noise is to roll-off the close-loop gain at the lower frequency by increasing the C522 feedback capacitor by 10x or more (>3nF). Increasing the feedback cap lowers the effective AC gain used to amplified the signal (and noise) and thus results in a lower noise at the output of the amplifier. Please see TI Precision Labs videos explaining this topic in greater detail:
    training.ti.com/ti-precision-labs-op-amps-noise-1