Totem pole-How is the output

Discussion in 'General Electronics Chat' started by nepdeep, Dec 11, 2012.

  1. nepdeep

    Thread Starter Member

    Sep 14, 2011
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    I went through some posts here. But still had dillema on how the output of the following circuit would look for logic 1 and 0.. As far as I can go it seems like an inverter to me?? Help me understand please. Untitled.jpg ...with bit of explanation please..:)
     
  2. tshuck

    Well-Known Member

    Oct 18, 2012
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    When a 1 is present on the CMOS device(last stage), the NMOS pulls the output low, while the PMOS doesn't conduct. Conversely, when a 0 is present on the input, the PMOS conducts while the NMOS does not, pulling the output up to +vdd(15V).

    But remember, the input is being inverted, so this device is inverting an inverted input making it a.....
     
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  3. nepdeep

    Thread Starter Member

    Sep 14, 2011
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    ......buffer...inverting buffer!!
     
  4. tshuck

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    Oct 18, 2012
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    Well, which is it? Is the final result inverted?
     
  5. ErnieM

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    Apr 24, 2011
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    No, the output in not inverted, but the input is. (huh?)
     
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  6. Ron H

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    Apr 14, 2005
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    ......buffer...noninverting buffer!!
     
  7. tshuck

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    Oct 18, 2012
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    Ding, ding, ding! I was hoping the OP would come to this on his own...the important thing is that he knows....
     
  8. tshuck

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    the idea was to get the OP to determine if the output was different than the input...
     
  9. Ron H

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    Yeah, I probably should have held my tongue... ermmm, fingers.:(
     
  10. nepdeep

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    Sep 14, 2011
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    Thanks for all the brains. Now my story.

    when the input (at figure) is 1 then NFET pulls Load to ground PFET doesnot conduct. so output is low
    so
    1 gives 0 (inverted)
    when the input is 0 then NFET doesnot conduct and PFET pulls output to 15 volts. so output is high
    so
    0 gives 1 (inverted again!!)

    Now from what ....................okey okey...okey...i was looking at the figure and typing this and suddenly saw the ball on the end of the arrow at input....that made me realise it was inverting input..okey now final conclusion hehehe
    1 gives 0
    0 gives 1
    so 1 -> 1

    0 gives 1
    1 gives 0
    so 0 -> 0

    thank you...hope i understood ??
     
  11. Ron H

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    Apr 14, 2005
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    You've gotta pay attention to your balls!:D
     
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  12. tshuck

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    Oct 18, 2012
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    Oh man, how did I miss that!?
     
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