Op amp in inverting voltage follower configuration

Discussion in 'General Electronics Chat' started by ecaits, May 26, 2016.

  1. ecaits

    Thread Starter Member

    Jan 6, 2014
    52
    0
    I want to use op-amp as a voltage follower configuration and positive dc voltage signal is applied to inverting terminal.
    So I should get same negative dc voltage on output.

    Which circuit I need to use??
     
  2. DickCappels

    Moderator

    Aug 21, 2008
    2,647
    632
    From your description, I think you are looking for this circuit. To make the gain 1:1 make Rin = Rf
    upload_2016-5-26_13-2-55.png
     
  3. crutschow

    Expert

    Mar 14, 2008
    12,984
    3,223
    "Inverting voltage follower" is a contradiction in terms.
    I believe you mean an inverting amp with a gain of (minus) one, which Dick's circuit will do.
     
  4. ecaits

    Thread Starter Member

    Jan 6, 2014
    52
    0
    Hi Zapper,

    Yes same thing which is require to do.
    Please can you post the circuit.
     
  5. ecaits

    Thread Starter Member

    Jan 6, 2014
    52
    0
    Hi DickCappels,

    Same thing I have already tried by simulator but not getting the expected output.
    Input DC voltage range is 300 mV to 800 mV and I have require -300 mV to -800 mV as output.
    I am using LMP7721 op-amp in my circuit.
    Can you please provide the +/- Vcc voltage...
     
  6. DickCappels

    Moderator

    Aug 21, 2008
    2,647
    632
    That looks like a very high-end opamp. To make it simple try ± 1.5 to 5 volts. You can make the resistors large, perhaps 100k if you don't need more than a couple hundred kHz bandwidth.
     
  7. crutschow

    Expert

    Mar 14, 2008
    12,984
    3,223
    Post your circuit and the simulator result.
     
  8. crutschow

    Expert

    Mar 14, 2008
    12,984
    3,223
    Can you show a plot of voltage versus time in your simulation results?
     
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