Do you know the advantages of class AB amplifiers?

Do you know the advantages of class AB amplifiers?

Class AB amplifier is actually a combination of Class A and Class B, with each device having a conduction time between 50-100%, depending on the magnitude of the bias current and the output level. The bias of this type of amplifier is designed according to Class B, and then the bias current is increased to make the amplifier enter Class AB.

The AB type working state usually involves two transistors working together. When there is no signal, both transistors are conducting, but the current in them is very small. When there is a signal input, the current in the transistor will increase. Due to the effect of the signal, when one transistor turns off, the other transistor must be conducting, and the two transistors always turn off and on, And almost all of the current flowing through it is fed into the speaker, so the heat generated by Class A and Class B amplifiers is relatively small and the efficiency is much higher, at over 70%.

When the output of Class AB amplifier is below a certain level, both output devices are conductive, and its state operates in Class A; When the level increases, both devices will be completely cut off, while the other device will supply more current. At the beginning of the AB class state, distortion will suddenly increase, and its linearity will be inferior to that of A or B classes. Its legitimate use lies in its supplement to Class A and its ability to continue working well when facing low load impedances.

（Class AB amplifier）

The bias of Class AB amplifier is between Class A amplifier and Class B amplifier. The efficiency of Class AB amplifier is much higher than that of Class A amplifier and slightly lower than that of Class B. The bias of Class AB amplifier can cover the working range of two transistors operating in push-pull mode. In this way, crossover distortion can be controlled by biasing it on AB class push-pull amplifiers, which are also commonly used in high-power amplifiers in electronic warfare. From the above, it can be seen that Class AB is an improved version of Class A and Class B.