circuit integrator for high frequency switching

Discussion in 'The Projects Forum' started by tira_othman, Jul 27, 2008.

  1. tira_othman

    Thread Starter New Member

    Jul 23, 2008
    6
    0
    hello everyone !!

    i was doing research based on this topic, but i couldn't find anything that satisfy me. i am looking for an integrator circuit, which has the clock (BJT) to control the high frequency dc switching. basically, this is for power electronics project.

    i supposed to do the input voltage feedforward pulse-width modulator for dc switching power converters. as for now, i need to find the integrator circuit which it can control the high frequency dc switching.

    anyone can help me ?

    thank u!
     
  2. tira_othman

    Thread Starter New Member

    Jul 23, 2008
    6
    0
    ok, i guess, everyone is not understand what am i saying .. so, this is the simulation picture, but i didnt get the sawtooth output as what my mission needs.
    so, pls help me with this .. i need to get an output like circuit integrator3 picture, but i must use transistor like circuit integrator4 .. but i cant get an output like circuit integrator3 .. can anyone really help me with this ?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The dark blue of the channel B trace is extremely difficult to see; it appears nearly black to me, and I can't make out the waveform very well.

    Can you make it something brighter, or change the background of the O-scope to a more contrasting color?
     
  4. tira_othman

    Thread Starter New Member

    Jul 23, 2008
    6
    0
    this is the pictures for circuit integrator2 (int2) and circuit integrator3 (int3) .. i want circuit integrator3 to produce sawtooth waveform like the output from int2 .. :confused: the 1st picture is output from circuit integrator2, the second one is from the circuit integrator3 .. from the previous post, i mentioned about 3 and 4, im sorry, it was wrong, i meant 2 and 3 ..
     
    Last edited: Aug 5, 2008
  5. bertus

    Administrator

    Apr 5, 2008
    15,649
    2,348
    Hello,

    Could you have a problem with the bandwith? (the signal look rounded).
    Your experiment is using 3 MHz, pretty close to the unity gain bandwith.
    The LF356 has a unity gain bandwith of 5 MHz.
    The LF357 has a unity gain bandwith of 20 Mhz.
    The LF 357 has also a larger slewrate of 50 V/uS.

    Greetings,
    Bertus
     
  6. tira_othman

    Thread Starter New Member

    Jul 23, 2008
    6
    0
    this is what happened when i changed it to 5MHz
     
  7. tira_othman

    Thread Starter New Member

    Jul 23, 2008
    6
    0
    hello ..

    the purple is the output .. is that correct for the sawtooth output ? this is only for positive part since transistor is connected. Does this graph makes any sense ?

    i really2 need opinions here !! :confused::confused::confused:
     
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