Eliminating Crossover Distortion in Transistors

Crossover distortion is a problem that occurs in Class B amplifier circuits. It happens when the input signal is close to zero, causing a brief period where neither transistor is conducting, leading to a distorted output waveform.

Understanding the Solution

To eliminate this crossover distortion, the transistors need to be kept in a slightly conductive state even when the input signal is zero. This is achieved by applying a small forward bias to the bases of the transistors.

• This small bias voltage (typically around 0.7V for silicon transistors) ensures that the transistors start conducting earlier and stop conducting later, bridging the "gap" where distortion occurs.
• This configuration effectively changes the amplifier class from Class B to Class AB.
• Class AB amplifiers provide a good compromise between the efficiency of Class B and the linearity of Class A amplifiers.

Therefore, applying a small forward bias to the bases is the correct method to eliminate crossover distortion.