Feedback is a widely used technique to improve the characteristics of an imperfect amplifier. A generalized amplifier with negative voltage feedback is shown in figure 3.15.
Figure 3.15: Amplifier with negative voltage feedback.
The overall transfer function (closed-loop gain) can be written as
Realizing that
we may write
If 
.
The transfer function is now independent of the amplifier gain.
is the transfer function of a stable resistive network which
means that 
will also be stable.