Q.What are the advantages of negative feedback?

Negative feedback trades a reduction in gain for a large improvement in the amplifier's overall quality, which is why almost every practical amplifier uses it.

[!ANSWER]

The advantages are: highly stabilised (constant) gain, reduced distortion, reduced noise, increased bandwidth, and input and output impedances that can be modified as desired.

[!TLDR]

Negative feedback gives stable gain, less distortion, less noise, wider bandwidth, and controllable input/output impedances — at the cost of reduced gain.

In negative feedback a fraction $\beta V_o$ of the output is returned $180^{\circ}$ out of phase, so the net input is reduced to $V_i = V_s - V_f$. Although this lowers the closed-loop gain to $A_f = A/(1+A\beta)$, it improves several amplifier characteristics that matter far more in a Karnataka 2nd PUC Electronics amplifier design:

• Highly stabilised gain — with $A\beta \gg 1$, $A_f \approx 1/\beta$, so the gain depends only on the passive feedback elements and not on device parameters, supply voltage or ageing.
• Reduced distortion — harmonic and non-linear distortion generated inside the amplifier are cut by the factor $(1+A\beta)$.
• Reduced noise — internally generated noise is similarly reduced.
• Increased bandwidth — the bandwidth widens by the factor $(1+A\beta)$.
• Impedance control — input impedance can be increased and output impedance decreased (in voltage-series feedback), improving matching with source and load.

[!ANSWER]

The advantages of negative feedback are highly stabilised gain, reduced distortion, reduced noise, increased bandwidth, and the ability to modify input and output impedances as desired.