Unity Gain Operational Amplifier

Discussion in 'General Electronics Chat' started by Dritech, Apr 1, 2016.

  1. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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    5
    Hi all,

    The OPA337 datasheet states that :

    Can the OPA337 be used for gains greater than 5, or just as a unity gain IC ?
    I am planning to implement an amplifier with a variable gain from 1 to 10. Since it can be set to unity gain (A = 1), I was opting for a unity gain stable op-amp. But are they good for gains greater than 1 ?
     
  2. Bordodynov

    Well-Known Member

    May 20, 2015
    1,097
    331
    Yes, you can use this op amp. It is important not to exceed the load capacity.
     
  3. #12

    Expert

    Nov 30, 2010
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    9,287
    Just because it's guaranteed stable down to a gain of one doesn't mean they revoked the stability at higher gains.
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Unity gain has more chance of oscillating over a higher gain as the feedback signal is the largest.
     
  5. crutschow

    Expert

    Mar 14, 2008
    16,503
    4,439
    The more feedback, the higher the chance of oscillating.
    So if the op amp is (non-inverting) unity-gain stable, with a feedback gain of 1, then it will be stable at higher gains, where the feedback gain is less than 1.
     
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Unity gain is most problematic as the feedback is greatest.

    Higher gains are more stable.

    (don't snooze before hitting send or someone will beat you to your point.)
     
  7. #12

    Expert

    Nov 30, 2010
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    Sorry. I was in the kitchen making coffee. What were you saying?:D
     
  8. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    761
    5
    Thanks for the replies. Is greater feedback/more feedback referring to higher gain? I cannot really understand when the OPA337 (a unity gain stable op-amp) gets unstable. How can I know that the op-amp will work correctly with gain varying from 1 to 10?
     
  9. #12

    Expert

    Nov 30, 2010
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    It doesn't get unstable for any gain equal to or greater than one.
    1) We just told you it would.
    2) The datasheet told you it is stable down to a gain of one volt per volt.
    That means it is stable for all gains equal to or greater than one.
     
    ErnieM and Dritech like this.
  10. ramancini8

    Active Member

    Jul 18, 2012
    462
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    Read a good op amp book because this subject is much deeper than this forum can go into.
     
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