Class A Amplifier

- A Class A amplifier is biased so that the output transistor is always conducting current, even when there is no input signal.
- It operates in the linear region of the transistor's characteristics, which means that the output signal is an amplified replica of the input signal.
- Class A amplifiers have the highest linearity and lowest distortion among the given options.

Linearity

- Linearity refers to the ability of an amplifier to reproduce the input signal accurately without any distortion.
- In a Class A amplifier, the output transistor is always conducting, which allows it to respond quickly and accurately to changes in the input signal.
- The amplifier provides a faithful reproduction of the input signal, resulting in high linearity.

Lowest Distortion

- Distortion occurs when the output signal deviates from the original input signal.
- Class A amplifiers have the lowest distortion because they operate in the linear region of the transistor's characteristics.
- This allows the amplifier to faithfully amplify the input signal without introducing significant distortions.

Comparison with Other Classes

- Class B amplifiers operate in a push-pull configuration, where one transistor conducts for positive half cycles of the input signal and the other conducts for negative half cycles.
- Class B amplifiers have higher distortion compared to Class A amplifiers because there is some crossover distortion when one transistor turns off and the other turns on.
- Class C amplifiers are biased to operate in a highly non-linear region, which results in high distortion. They are mainly used in applications where distortion is not critical, such as RF amplification.
- Class B push-pull amplifiers combine the advantages of Class A and Class B amplifiers by using two transistors to reduce distortion. However, they still have higher distortion compared to Class A amplifiers.

Conclusion

In conclusion, Class A amplifiers have the highest linearity and lowest distortion among the given options. They operate in the linear region of the transistor's characteristics, allowing them to faithfully amplify the input signal without introducing significant distortions.