Transconductance in differential amplifier

Discussion in 'Homework Help' started by screen1988, Jun 27, 2013.

  1. screen1988

    Thread Starter Member

    Mar 7, 2013
    310
    3
    I need help. In this video Differential Amplifiers at 0:47:41, the transconductance Gm = ∂ΔId/∂ΔVin

    [​IMG]

    I don't understand why both partial derivative ∂ and delta Δ used here.
    I usually see that only one of them is used in the definition of Gm.
    Gm = ∂Id/∂Vin or Gm = ΔId/ΔVin
     
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  2. WBahn

    Moderator

    Mar 31, 2012
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    4,796
    I'm not going to even try to get 47 minutes into a video with my satellite connection, so I'm having to guess.

    They probably have a function that uses the Δ simply as part of the name and then they are taking the partial derivative of one such function with respect to another.

    But without see how the functions are defined, I can't tell.
     
    screen1988 likes this.
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Being a differential amplifier perhaps the Delta term refers to the differential voltage & current....??
     
    screen1988 likes this.
  4. screen1988

    Thread Starter Member

    Mar 7, 2013
    310
    3
    Ah, I think you are right! I didn't notice about this.
     
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