Fundamentals of Microelectronics, 2nd Edition

Feedback

Feedback is an integral part of our lives. Try touching your fingertips together with your eyes closed; you may not succeed the first time because you have broken a feedback loop that ordinarily “regulates” your motions. The regulatory role of feedback manifests itself in biological, mechanical, and electronic systems, al lowing precise realization of “functions.” For example, an amplifier targeting a precise gain of 2.00 is designed much more easily with feedback than without.

This chapter deals with the fundamentals of (negative) feedback and its application to electronic circuits. The outline is shown below.

12.1   GENERAL CONSIDERATIONS

As soon as he reaches the age of 18, John eagerly obtains his driver’s license, buys a used car, and begins to drive. Upon his parents’ stern advice, John continues to observe the speed limit while noting that every other car on the highway drives faster. He then reasons that the speed limit is more of a “recommendation” and exceeding it by a small amount would not be harmful. Over the ensuing months, John gradually raises his speed so as to catch up with the rest of the drivers on the road, only to see flashing lights in his rear-view mirror one day. He pulls over to the shoulder of the road, listens to the sermon given by the police ...