Efficiency of a Class AB Amplifier

Discussion in 'General Electronics Chat' started by nathalie, May 9, 2011.

  1. nathalie

    Thread Starter New Member

    Jan 9, 2011
    14
    1
    Efficiency of a Class AB Amplifier
    How can i calculate the efficiency of a class AB amplifier circuit?

    How can I determince Ps in the equation

    efficiency = P(load) / Ps(supply) *100%

    Thansk
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,962
    1,097
    If the input signal is Vin = Vp*sin(ωt)
    Then

    Ie=\frac{Vp}{R_L}*sin(\omega t)

    So the the instantaneous electric power form power supply is equal

    p_z=Vcc*i_e = \frac{Vcc*Vp}{R_L}*sin(\omega t)

    So to find average supply power you need to solve this

    Ps = \frac{1}{\pi} \int\limits_{0}^{\pi} Vcc*i_e d(\omega t)= \frac{1}{\pi} \int\limits_{0}^{\pi}\frac{Vcc*Vp}{R_L}sin(\omega t) d(\omega t)
     
    Last edited: May 9, 2011
  3. nigelwright7557

    Senior Member

    May 10, 2008
    487
    71
    It depends on the voltage out as to how much is power to the speaker and how much to the heatsink. Class AB is typically 60% efficient with 40% of power dumped into the heatsink.
     
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