Small Signal Analysis-BJT/FET

Discussion in 'Homework Help' started by no12thward, Feb 22, 2011.

  1. no12thward

    Thread Starter Member

    Jan 10, 2011
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    0
    Do the boxed values here seem to be correct for these 2 BJT and 1 FET circuits? Mainly the "Av" values I am concerned of. Is it supposed to be a negative number?
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Av is voltage gain, not a resistance.
    Ai is current gain, not a resistance.

    The transistor inverts the signal so the gains are negative.
     
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  3. no12thward

    Thread Starter Member

    Jan 10, 2011
    30
    0
    So the current gain would end up being negative as well, or just the voltage gain?
     
  4. The Electrician

    AAC Fanatic!

    Oct 9, 2007
    2,283
    326
    As Audioguru said, get rid of those k and Ω suffixes on your Av, Ai, and Vo results. The gains Av and Ai are dimensionless ratios. Sometimes you will see Av specified like, for example, 100 V/V (volts per volt) for a voltage gain of 100, but the V/V units cancel so the result is really dimensionless.

    Also, on page 1/3, you have copied your Zo and Zi values from your calculations into the wrong boxes.
     
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