next up previous contents
Next: Problems Up: Amplifier Model Previous: One-Two- and Three-Pole

Amplifier with Negative Feedback

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.

Doug Gingrich
Tue Jul 13 16:55:15 EDT 1999