1 Answer
**Negative feedback** in amplifiers is a technique where a portion of the output signal is inverted and fed back to the input. This feedback opposes the input signal, thereby "correcting" any deviations in the amplifier's performance. Here's a breakdown of the concept:
### How It Works:
* An amplifier has an input signal and produces an amplified output.
* In **negative feedback**, a fraction of the output is taken, inverted, and combined with the input.
* This reduces the overall input to the amplifier, hence the term “negative.”
### Key Benefits:
1. **Stabilized Gain**: The gain of the amplifier becomes less sensitive to component variations.
2. **Improved Linearity**: Reduces distortion by linearizing the amplifier's transfer characteristics.
3. **Reduced Noise**: Feedback can suppress internally generated noise.
4. **Increased Bandwidth**: The frequency response becomes wider.
5. **Better Impedance Characteristics**:
* Increases input impedance.
* Decreases output impedance.
### Mathematical Insight:
If an amplifier has a gain $A$, and a fraction $\beta$ of the output is fed back, the **closed-loop gain** becomes:
$$
A_{cl} = \frac{A}{1 + A\beta}
$$
This shows that even if $A$ changes due to temperature or aging, the overall gain $A_{cl}$ remains stable as long as $A\beta \gg 1$.
Would you like a diagram to visualize the feedback process?
### How It Works:
* An amplifier has an input signal and produces an amplified output.
* In **negative feedback**, a fraction of the output is taken, inverted, and combined with the input.
* This reduces the overall input to the amplifier, hence the term “negative.”
### Key Benefits:
1. **Stabilized Gain**: The gain of the amplifier becomes less sensitive to component variations.
2. **Improved Linearity**: Reduces distortion by linearizing the amplifier's transfer characteristics.
3. **Reduced Noise**: Feedback can suppress internally generated noise.
4. **Increased Bandwidth**: The frequency response becomes wider.
5. **Better Impedance Characteristics**:
* Increases input impedance.
* Decreases output impedance.
### Mathematical Insight:
If an amplifier has a gain $A$, and a fraction $\beta$ of the output is fed back, the **closed-loop gain** becomes:
$$
A_{cl} = \frac{A}{1 + A\beta}
$$
This shows that even if $A$ changes due to temperature or aging, the overall gain $A_{cl}$ remains stable as long as $A\beta \gg 1$.
Would you like a diagram to visualize the feedback process?