"noninvert" - 1 õppematerjal

Book Analog Interfacing to Embedded Microprocessors

The remainder of this chapter will address feedback control systems. Negative Feedback and Control Figure 5.1 shows a simple control system—an opamp. The opamp has very high gain, and by connecting the output to the inverting input, we introduce negative feedback. The opamp amplifies the difference between the inverting and noninverting inputs. Say that the input and output are at 2v. The difference between the input and the output is 0v, so the difference between the inverting and noninvert- ing inputs is also 0v. The opamp, which amplifies this difference, has no dif- ference to amplify. 103 Figure 5.1 Simple control system: an opamp. Now, if the input changes suddenly from 2v to 2.1v, there will be a differ- ence between the two inputs—the noninverting input is at 2.1v, and the invert- ing input, still connected to the output, is at 2v. The .1v difference is amplified