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OPA211: Instrument to measure the untra-low noise

Hao Wang14
Expert 4415 points
Part Number: OPA211

Hi Team,

The datasheet says the input voltage noise is 80nVPP (0.1 to 10 Hz), may I know which kind of instruments is used to measure such low noise? Because now we want to measure the 20uVRMS noise (0 ~100kHz), but there is no such instruments to measure such low voltage. Could you please tell the brand or the name of the instruments which is used to measure it? 

Thanks and Best Regards!

Hao

  • 0
    TI__Guru* 93105 points

    Hello Hao,

    We don't use any particularly special equipment here in application engineering when we measure noise; however, the characterization team uses more sophisticated equipment but we cannot disclose their methods.

    Basically, here in applications we use a simple two-stage amplifier configuration. Both the amplifier under test and the op amp that follows are placed in a high gain to amplify the amplifier under test noise. The board containing the two amplifiers is placed in a metal enclosure, and the op amps are powered by series-connected 9 V batteries. Exteranious noise entering the high gain measurement circuit is one of the more difficult factors to cope with and resolve. The enclosure has BNC or SMA connectors to route the amplified noise through a shielded cable connected to the measurement instrument.

    The TI Precision Amplifiers Op amp series in Section 8.7 and 8.9 provide information about using an O-scope to make the measurement. I suggest taking a look at that series and the methods applied. That should serve as a good starting place:

    https://training.ti.com/ti-precision-labs-op-amps-noise-7

    Also see the PDFs for download on that webpage and Art Kay's original Tech Day presentation on Op amp noise:

    Op-Amp Noise and Measurment_Oct_2013.pdf

    Regards, Thomas

    Precision Amplifiers Applications Engineering