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OP296 input resistance

mateohg93
on Sep 10, 2014

Hi, i would like to know the OP296 input resistance. I was wondering if the OP296 works as a transimpedance amplifier with a 1M feedback resistance (so i need that value). any advice?.


And the same question for ADA4528.

Thanks.

  • 0
    •  Analog Employees 
    on Sep 10, 2014 11:00 PM

    Mateo,

       How were you going to use input resistance?   It's generally of limited usefulness

    and for a voltage follower, the input resistance is bootstrapped by the open loop gain

    at that frequency.  For error calculations, input bias current can be used.

      I would not do a new design with the OP296 which came out in 1995.  I would use the next generation,

    ADA4096-2.

    Harry

  • 0 on Sep 11, 2014 11:49 AM

    Hello,

    the worst case input bias current of the OP296 is +-50nA, which you have to add or deduct from the current of your source (a photodiode, for example). Say, your photodiode sources 500nA then you expect 0.5V at the output of your opamp. In a worst case situation you will only get 0.45V or even 0.55V.

    The input offset current is not included in the calculation.

    Best regards,

    Reinhard

  • 0
    •  Analog Employees 
    on Aug 2, 2018 2:45 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin