Virtual Slew Rate

Discussion in 'Homework Help' started by Bethan Davies, Nov 27, 2014.

  1. Bethan Davies

    Thread Starter New Member

    Nov 27, 2014
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    So in my assignment i have to work out the the slew rate for the component opamp_3T_virtual in multisim, i have no given resister values or circuit and no idea where to start.
     
  2. MrAl

    Well-Known Member

    Jun 17, 2014
    2,418
    488
    Hi,

    If you already have the model maybe you can drive it with a square wave and look at the output response. If you look at the places where it ramps up and/or down vs time, you can calculate the slew rate. For example if it ramps up by 2 volts in 1 microsecond, then the slew rate is 2v/us.
     
  3. Bethan Davies

    Thread Starter New Member

    Nov 27, 2014
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    I know slew rate is the voltage over time, and I know how to calculate the maximum slew rate needed, but I don't know how to test a slew rate. Or am I just looking at this wrong?
    I have tried testing it with a square wave but I shall try again. Thank you.
     
  4. Bethan Davies

    Thread Starter New Member

    Nov 27, 2014
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    I tried increasing the input frequency to 100MHz with the results as shown upload_2014-11-28_0-27-23.png
     
  5. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    Your amplifier is not correct.

    Design a non-inverting amplifier with a gain of 2.

    Set your signal generator to 10 kHz @ 1 V peak to peak.

    Trigger your oscilloscope.

    Post your screen shot ... and you can crop out the superfluous information in paint.
     
  6. crutschow

    Expert

    Mar 14, 2008
    12,972
    3,219
    Try increasing the voltage to at least 10Vpp.
     
  7. Bethan Davies

    Thread Starter New Member

    Nov 27, 2014
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  8. Bethan Davies

    Thread Starter New Member

    Nov 27, 2014
    6
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    And at 10V it still looks similar to the first screen shot. Thank you both for your help on this
     
  9. Bethan Davies

    Thread Starter New Member

    Nov 27, 2014
    6
    0
    So I went in and asked and was told the curve i am getting is fine for a virtual op amp, most real op amps will have this but not for a wide range of frequency's where as a virtual one curves the signal a lot more. Thank you all for your help.
     
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