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LMP2011/TL061 input-referred current noise

Kuramochi Tadahiko
Guru 28715 points
Other Parts Discussed in Thread: TL061, LMP2011, TL072, LMP2021

Hi,

My customer needs the following information.

Could you show me the input--referred current noise of LMP2011 & TL061?

Thanks and Regards,

Kuramochi / Japan disty

  • 0
    TI__Guru**** 154506 points
    Tadahiko-san,

    I found current noise data for TL072 that was about 0.1pA/rtHz (at 1kHz). TL061 should be the same.
  • 0 in reply to Ron Michallick
    Guru 28715 points
    Ron-san,
    Thank you.
    How about LMP2011?
    Regards,
    Kuramochi
  • 0
    TI__Guru 54226 points

    Hello Tadahiko,

    The LMP2011 is a "chopper" amplifier. The input pins will have large, pulsating currents in and out of the inputs.

    You cannot really measure the "current noise" since it is buried in the noise of the charge injection due to the CMOS "chopper" switch noise. Therefore we could not measure it with any real accuracy. That line should have been removed. The LMP2021 datasheet explains this, and the weird dependance on input capacitance balancing.

    You can think of the chopper noise as repetitive current noise (current pulses). The higher the input impedance, the more voltage is generated across the input impedance, and the worse the overall noise.

    We do not recommend the use of the LMP2011 with source impedance of more than 1M Ohm. If the application is concerned with current noise, then the LMP2011 will not be suitable.

    Art/John/Collin - did you ever publish the results of the your investigation of the chopper input pulses?

    Regards,

  • 0 in reply to Paul Grohe
    Guru 28715 points

    Hello Paul,

    Thank you for your information.
    I confirmed the LMP2021 datasheet.
    It indicates the input--referred current noise "350fA/√Hz".
    I think that this current noise includes pulsating currents.
    Is it corrct?

    Thanks and Regards,
    Kuramochi

  • 0 in reply to Kuramochi Tadahiko
    TI__Guru 54226 points
    Hello Kuramochi,

    That would probably be the current noise *between* the pulses. The pulses can reach 10's of pA for several hundred nanoseconds.

    The LMP2011 and 2021 are different devices. So 350fA may not apply to the 2011. Either one is not recommended for input current noise sensitive applications.

    Regards,
  • 0 in reply to Paul Grohe
    Guru 28715 points

    Hello Paul,

    Thank you for your quick response.
    I understood.

    Regards,
    Kuramochi