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Is Amplification same as gain?

  1. Mar 2, 2013 #1
    Hello,

    I can't figure out what's the difference between the two:
    Gain - how much the amplitude of the signal was increased/decreased
    Amplification - how much the amplitude of the signal was increased/decreased

    If we take a basic inverting amplifier circuit:
    http://alturl.com/39n78

    We can see an amplification of signal by 3 times from 5V to 15V
    This is equivalent increase of 300%
    300% to dB would mean a gain of 4.77dB according to this source

    Is gain (dB) simply an amplification rate in different units?

    Thanks.
     
  2. jcsd
  3. Mar 2, 2013 #2
    First of a gain of 3 from 5V to 15V is not a 300% increase, it's a 200% increase. Yes, the calculator you reference does show that a gain of 3 is 300%, but that's not the same as a 300% increase. A 100% increase would be an increase from 5V to 10V. Second the dB calculator is calculating power increase not voltage increase. Power gain varies as the square of voltage increase. A voltage gain of 3 would have a dB value of 9.54 dB.

    Gain is often expressed as dB so the gains of multiple stages of other elements can be added together instead of multiplied or divided. It's not different units, it's a different mathematical operation. For voltage gain you should use the formula 20 * Log(Vout/Vin).
     
  4. Mar 2, 2013 #3

    davenn

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    Gold Member

    amplification is what is "occurring ... the gain figure quantifies the amount of amplification occurring


    and to follow on from skeptic2's formula above ....

    power gain = 10 * Log (Pin/Pout)

    Dave
     
    Last edited: Mar 2, 2013
  5. Mar 3, 2013 #4
    Super simple, thanks.
     
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