What is the efficiency of Class B amplifier?

When Class-B amplifiers amplify the signal with two active devices, each operates over one half of the cycle. Efficiency is much improved over class-A amplifiers. Class-B amplifiers are also favoured in battery-operated devices, such as transistor radios. Class B has a maximum theoretical efficiency of π/4 (≈ 78.5%).

How do you calculate the efficiency of a Class B power amplifier?

Where Idc is the average current drawn from the supply VCC . Since, the transistor is on for alternating half-cycles, it effectively acts as a half-wave rectifier . Thus, the maximum collector efficiency of class B power amplifier is 78.5% .

What is power amplifier efficiency?

Power-Added Efficiency (PAE) expresses the overall efficiency of the power amplifier, including the effect of the input power. PAE is usually expressed as a percent. For example, a power amplifier having an output power of 10 W, an input power of 0.5 W and DC power of 30 W would have a PAE = (10-0.5)/30 = 32%.

What is the efficiency of Class A power amplifier?

Output Characteristics of Class A Power Amplifier The theoretical maximum efficiency of a Class A power amplifier is 50%. In practice, with the capacitive coupling and inductive loads (loudspeakers), the efficiency can decrease as low as 25%.

What is the maximum efficiency of a Class B power amplifier?

Theoretical maximum efficiency of Class B power amplifier is 78.5%. The schematic of a single ended Class B amplifier and input , output waveforms are shown in the figure below. From the above circuit it is clear that the base of the transistor Q1 is not biased and the negative half cycle of the input waveform is missing in the output.

What should be the conduction angle of a Class B amplifier?

That means the conduction angle is 180° for a Class B amplifier. Since the active device is switched off for half the input cycle, the active device dissipates less power and hence the efficiency is improved. Theoretical maximum efficiency of Class B power amplifier is 78.5%.

Why is power dissipation high in Class B power amplifier?

But during the negative half cycle of the input, the circuit is reverse biased and the collector current will be absent. Hence only the positive half cycle is amplified at the output. As the negative half cycle is completely absent, the signal distortion will be high. Also, when the applied signal increases, the power dissipation will be more.

Which is more efficient Class A or Class G amplifiers?

Class-G amplifiers (which use “rail switching” to decrease power consumption and increase efficiency) are more efficient than class-AB amplifiers. These amplifiers provide several power rails at different voltages and switch between them as the signal output approaches each level.