Negative feedback is a control mechanism used in electronic amplifier circuits to improve performance and stability. It involves feeding a portion of the output signal back to the input in a way that it opposes any changes in the input signal. This results in a more controlled and accurate amplification of the input signal.
The primary purpose of negative feedback in amplifier circuits is to achieve the following benefits:
Improved Linearity: Negative feedback helps reduce distortion in the amplified output signal. When the amplifier operates in its linear region, the output signal is a faithful reproduction of the input signal, with reduced harmonic distortion.
Increased Bandwidth: Negative feedback can help extend the usable bandwidth of an amplifier by reducing the gain at higher frequencies, where the amplifier's performance might otherwise degrade.
Stability: Amplifiers with negative feedback tend to be more stable and less prone to oscillations or other undesirable behaviors. The feedback mechanism makes the amplifier less sensitive to variations in component characteristics and temperature.
Reduced Noise: Negative feedback can help suppress noise and improve the signal-to-noise ratio of the amplifier.
Lower Output Impedance: Negative feedback typically reduces the output impedance of the amplifier, making it better suited to driving various types of loads, such as speakers.
Improved Distortion Characteristics: By counteracting the non-linearities of the amplifier circuit, negative feedback can reduce certain types of distortion, such as crossover distortion in class-AB amplifiers.
The overall impact of negative feedback on amplifier performance is generally positive, as it helps create a more accurate, linear, and stable amplification of the input signal. However, it's important to note that excessive negative feedback can lead to certain trade-offs, such as reduced gain and potentially increased phase shift, which could affect the amplifier's transient response and stability.
In summary, negative feedback is a technique used in amplifier design to enhance performance characteristics, such as linearity, bandwidth, stability, and noise reduction. It plays a crucial role in achieving high-quality audio and signal amplification in various applications, ranging from audio amplifiers to communication systems.