Offset Cancellation for comparator

Discussion in 'General Electronics Chat' started by screen1988, May 8, 2013.

  1. screen1988

    Thread Starter Member

    Mar 7, 2013
    310
    3
    Hi,
    I am learning Offset Cancellation for comparator. Here is what I understaning so far.
    First, S1 open, S2,3,4,5 closed:
    [​IMG]
    In this case, I can understand how C1, C2 and C3 are charged and calculate their voltages as in the picture.
    And here is what I am stuck.
    S3 open first:
    [​IMG]
    In the picture, the voltage at X is Vx = ε3 but I can't understand it.
    Why it is not -Vc1 = -A1* Vos1? Oh, I see it. Vc1 is only the voltage across the capacitor C1 not reference to ground.
    Now I can't understand how "Switch offset , ε3 induced on node X" as in the picture? What is the induced volatge and how can I calculate it? Thanks.
     
    Last edited: May 8, 2013
  2. screen1988

    Thread Starter Member

    Mar 7, 2013
    310
    3
    Any help? This is not homework. I learn myself and get stuck.
     
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