Effect Of Finite Open Loop Gain and Bandwidth On Circuit Performance fb by NDfLRGk

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									Chapter 2 – Operational Amplifiers

Introduction
http://engr.calvin.edu/PRibeiro_WEBPAGE/courses/engr311/Handouts/OpAmp-tutorial-1.ppt

Textbook CD

http://www.clarkson.edu/%7Esvoboda/eta/designLab/InvertingAmplifierDesign.html
The OP-AMP Terminals

Symbol

Power Supplies
Fairchild uA702 – The first op-amp designed by Bob Widlar
The OP-AMP Terminals
The OP-AMP Terminals
The Ideal OP-AMP



                i(-)           _
    Inverting
                                            RO
                         vid            A                    Output
                                   Ri
                                                            vO = Advid
 Noninverting
                  i(+)         +

                                                 -VS


                                                 Open-loop gain
Exercise 2.2
Analysis of Circuits Containing Ideal OP-AMPS

         The Inverting Configuration




Closed-Loop Gain

Virtual Short-Circuit

Virtual Ground

Negative and Positive Feedback

                          The inverting closed-loop configuration.
Analysis of Circuits Containing Ideal OP-AMPS

      The Closed-Loop Gain




                                                          -




                Analysis of the inverting configuration
Analysis of Circuits Containing Ideal OP-AMPS

      Effect of Finite Open-Loop Gain

                                                   vo                vo
                                             vI               vI 
                                        i1
                                                   A                  A
                                                    R1             R1

                                                                             vo   
                                             v o                v o  v I  A    
                                        vo           i1 R2                       R2
                                              A                   A    R1         
                                                           R2
                                             vo             R1
                                        G
                                             vI          1  R2 
                                                                
                                                     1
                                                             R1 
                                                               A
Analysis of Circuits Containing Ideal OP-AMPS

      Exercise 2.1
Analysis of Circuits Containing Ideal OP-AMPS

      Input and Output Resistances



              vI   vI
         Ri              R1
              iI    vI

                   R1


         Ro   0
Analysis of Circuits Containing Ideal OP-AMPS

      Exercise 2.2
Other Applications of the Inverting Configuration

         With General Impedances


                                   R2
                                   Z2

            i       R1
                s
                    Z1
                                                    vo
    vs                         +
Other Applications of the Inverting Configuration

       The Integrator


                        i                                          t
                            c       C                      1 
                                             v o ( t)           v I( t) dt
             R                                            C R 
       is                                                          0

                    i-                       Vo           1
vs                              +            VI         s  C R
                                        vo
Other Applications of the Inverting Configuration

       PSpice Simulation Tips
Other Applications of the Inverting Configuration

         The Differentiator
                                 Z2 = R
                                     R2

                     Z1 = 1/sC
             i            R1
                 s

                                                    vo
    vs                           +
Other Applications of the Inverting Configuration

       The Weighted Summer
Other Applications of the Inverting Configuration

       The Non-Inverting Configuration


                                             vo
                                v2  v1                  A   infinit e
                                             A
                                             vI
                                vo    vI          R2
                                             R1
       vi
                                vo           R2
                                      1
                                 vI          R1
Other Applications of the Inverting Configuration

       The Voltage Follower
Other Applications of the Inverting Configuration

             The Difference Amplifier




 A difference amplifier.
Other Applications of the Inverting Configuration

             The Difference Amplifier




 Applications of superposition to the analysis of the current circuit of Fig.. 2.21.
Other Applications of the Inverting Configuration

             The Difference Amplifier – Input Resistances




 Finding the input resistance of the difference amplifier.
Other Applications of the Inverting Configuration

             The Difference Amplifier – Common-Mode and Differential
             Components of the input signal




 Representation of the common-mode and differential components of the input signal to a difference amplifier. Note that v1 = vCM - vd/2
 and v2 = vCM + vd/2.
Other Applications of the Inverting Configuration

             Instrumentation Amplifier




 (a) A popular circuit for an instrumentation amplifier. (b) Analysis of the circuit in (a) assuming ideal op-amps. (c) To make the gain
 variable, R1 is implemented as the series combination of a fixed resister R1f and a variable resistor R1v. Resistor R1f ensures that the
 maximum available gain is limited.
 Effect Of Finite Open-Loop Gain and Bandwidth On Circuit
 Performance




Open-loop gain of a typical general-purpose internally
compensated op amp.                                      fb = 3-db or break frequency
                                                         ft = unity gain bandwidth
 (a) Unity-gain follower. (b) Input step waveform. (c) Linearly rising output waveform obtained when the amplifier is slew-rate
limited. (d) Exponentially rising output waveform obtained when V is sufficiently small so that the initial slope (wtV) is smaller then or
equal to SR.
Effect of slew-rate limiting on output sinusoidal waveforms.

								
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