When should i place buffers?

Discussion in 'General Electronics Chat' started by Sink00, Feb 18, 2010.

  1. Sink00

    Thread Starter New Member

    Feb 13, 2010
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    Hi i am developing a circuit with some opamps stages like inverting amplifier, non-inverting amplifier, precision rectifier, first and second order active filters and finally the signal goes to an PIC's ADC. Should i place buffers between stages or it is not necessary? The circuit is attached. Some of the words are in portguese but i think the stages are self explaned. Can i remove any of the buffers?

    Thanks
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    The buffers that have the very low output impedance of another opamp as their input are absolutely useless.
     
  3. Sink00

    Thread Starter New Member

    Feb 13, 2010
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    Can you point the useless buffers? Or are all useless? And should i place a buffer before A/D? Thanks
     
  4. mik3

    Senior Member

    Feb 4, 2008
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    The only buffers which are really required are the buffers before the ADC inputs.
     
  5. Sink00

    Thread Starter New Member

    Feb 13, 2010
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    Thank you. Just to confirm, the two pararell circuits connected to the output of the non-inverting amplifier will not cause interference with each other them correct? Thanks again.
     
    Last edited: Feb 18, 2010
  6. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    I count four boxes labeled "buffer" that are redundant.
     
  7. Sink00

    Thread Starter New Member

    Feb 13, 2010
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    Now i am confused. Should i place or not a buffer between low pass filter and ADC?

    Thanks again!!
     
  8. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    No, because the output from the LPF is coming right out of that OpAmp's output pin. You would only need the buffer if there was some series resistance (other than wire resistance) in the path between an output pin and the ADC input.
     
  9. Sink00

    Thread Starter New Member

    Feb 13, 2010
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    Thank you very much!! Woa i loved this forum. people ar very willing to help!!
     
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