Efficiency of a Class AB Amplifier

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nathalie

Joined Jan 9, 2011
14
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
 

Jony130

Joined Feb 17, 2009
5,487
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:
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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