In this theory, comparison of Class A, Class B and Class C Power Amplifier on the different parameter basis is given. The comparison of the Class A, Class B and Class C Power amplifier is done on the basis of transistor bias and amplitude of the input signal.

Compare: Class A, Class B & Class C Power Amplifier

Class A Amplifier	Class B Amplifier	Class C Amplifier
The transistor is biased so that the output current flows for the entire input cycle.	The transistor is biased so that the output current flows for half cycle of the entire input cycle.	The transistor is biased so that the output current flows for less than the half cycle of the entire input cycle.
The transistor is remains forward biased throughout the input cycle.	The transistor is remained forward biased for half of the input cycle.	The transistor is remained forward biased for less than the half of the input cycle.
The conductor angle is 360 degree.	The conductor angle is 180 degree.	The conductor angle is less than 180 degree.
The Q point is located at the centre of the load line.	The Q point is located at the cut off or very closed to it.	The Q point is located at the cut off point.
The maximum collector efficiency of the class A amplifier is 50%.	The maximum collector efficiency of the class B amplifier is 78.5%	The maximum collector efficiency of the class B amplifier is 85% to 90%.
Less signal distortion	Signal distortion is high as compared to class A amplifier.
The class A amplifier is used for power amplification of small amplitude. Large signal will shift the operating point near to cut off or saturation region.	The class B amplifier is used in the push – pull amplifier in which two transistors are used, one used during positive half cycle of the supply and second used for negative half cycle of the supply.	The class C amplifier never used in the power amplification, they are used as tuned amplifiers at radio frequencies.

 

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