6.3.1 Output Impedance

Chapter 6.3.1 Output Impedance

Physics Lecture Notes – Phys 395 Electronics Book
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Physics Lecture Notes – Phys 395 Electronics Book

  • CHAPTER 6. OPERATIONAL AMPLIFIERS123Figure 6.27: Straight-line approximation to|G| for amplifier d).input impedance, small but non-zero output impedance and large but finite open-loop gain.They also have voltage and current asymmetries at the inputs. We will analyze some circuitsusing an finite open-loop gain and consider output impedance, input impedance, and voltageand current offsets.6.3.1Output ImpedanceAn op-amp will in general have a small resistive output impedance from the push-pull outputstage. We will model the open-loop output impedance by adding a series resistor R0 to theoutput of an ideal op-amp as shown in figure 6.28.IVoutR0V1VinFigure 6.28: Real, current-limiting operational amplifier partially modeled by an ideal am-plifier and an output resistor.Assuming no current into the input terminals (unloaded), and hence no current through