---
+ Post New Thread
Results 1 to 5 of 5
  1. #1
    Member level 5
    Points: 1,245, Level: 7

    Join Date
    Nov 2008
    Posts
    90
    Helped
    4 / 4
    Points
    1,245
    Level
    7

    op amp integrator differentiator

    Plz explain me physically
    How the capacitor when connected at the output (feedback) of opamp acts as integrator & when connected at the input of opamp acts as differentiator?

    •   Alt17th December 2008, 04:29

      advertising

        
       

  2. #2
    LvW
    LvW is offline
    Advanced Member level 5
    Points: 36,120, Level: 46
    LvW's Avatar
    Join Date
    May 2008
    Location
    Germany
    Posts
    5,155
    Helped
    1524 / 1524
    Points
    36,120
    Level
    46

    op amp differentiator

    Quote Originally Posted by mess123
    Plz explain me physically
    How the capacitor when connected at the output (feedback) of opamp acts as integrator & when connected at the input of opamp acts as differentiator?
    One way to explain the function of the circuit is as follows:
    An opamp with neg. feedback has a voltage at the neg. terminal which is app. zero (virtual ground principle).
    1.) Integrator: With this in mind you simply write the input current Iin=Vin/R and the output voltage Vout=1/C(∫Iout•dt). Then, replace Iout=-Iin and you get the desired result.

    2.) Differentiator: Do the same for Iin and Vout.

    For my opinion, that is the most simple explanation. But keep in mind that not the capacitor ALONE acts as an integrator. It is the whole circuitry !!



    •   Alt17th December 2008, 07:56

      advertising

        
       

  3. #3
    Full Member level 5
    Points: 3,089, Level: 13

    Join Date
    Jul 2006
    Posts
    266
    Helped
    23 / 23
    Points
    3,089
    Level
    13

    function of differentiator in op-amp

    for an ideal opamp in negative feedback the voltage at the virtual ground node on the positive terminal is equal to the voltage at the virtual ground node on the negative terminal. assume virtual ground node is at 0V. therefore, voltage between output node to ground is equal to voltage between output node to virtual ground = voltage across the feedback capacitor(Vc). Vc is integral of the current through it (as a consequence of electrostatic theory). the current throught the capacitor is = current through resistor = Vin/R. hence the Vc = Vout is an integral of Vin with some proportionality constant.

    if the capacitor is in the input and resistor in the feedback, the input current = Ic = CdVin/dt. this flows through resistor, hence a differentiator.



    •   Alt17th December 2008, 17:49

      advertising

        
       

  4. #4
    Newbie level 3
    Points: 430, Level: 4

    Join Date
    Aug 2010
    Location
    pak
    Posts
    3
    Helped
    0 / 0
    Points
    430
    Level
    4

    op amp integrator & differentiator

    check the link, it would lead you to the concept,

    why it is called integrator?
    and, how, it is working?

    http://www.circuit-fantasia.com/circ...integrator.htm



  5. #5
    FvM
    FvM is offline
    Super Moderator
    Points: 171,707, Level: 98
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    27,816
    Helped
    8774 / 8774
    Points
    171,707
    Level
    98

    Re: op amp integrator & differentiator

    Perhaps it is helpful to someone, however I would clearly contradict this statement about the basic inverting OP integrator circuit:
    "It will be simple, small, easy remembering but... nonunderstandable!"



+ Post New Thread
Please login