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Chapter 6 The Operational Amplifier
Engineering Circuit Analysis Sixth Edition
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin
Copyright © 2002 McGraw-Hill, Inc. All Rights Reserved.
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Fig. 6.2 (a) Electrical symbol for the op amp...
Fig. 6.3 (and 6.4) Inverting amplifier.
Fig. 6.5 (and 6.6) Noninverting amplifier.
Fig. 6.8 Basic summing amplifier circuit with three inputs.
Fig. 6.9 Basic difference amplifier.
Fig. 6.14 A more detailed model for the op amp.
Fig. 6.15 Inverting amplifier circuit drawn using detailed model.
Fig. 6.18 Output-input characteristics of a real op amp circuit…
Inverting Amplifier
Ii =Vi +VdRi
, I f =−Vd −VoRf
, I i =I f , Vo =AVd
Vi +Vo / ARi
=−Vo / A+Vo
Rf
⇒ Rf Vi +Vo / A( ) =−RiVo 1 / A+1( )
VoVi
=−ARf
A+1( )Ri + Rf
⇒VdVi
=−Rf
A+1( )Ri + Rf
Inverting Amplifier
VoVi
=−ARf
A+1( )Ri + Rf
⇒VdVi
=−Rf
A+1( )Ri + Rf
Let Vi =1V , Ri =1kΩ , Rf =10kΩ , A=100.
Vo =−106
1.01×105 +104 ×1V=−9.009V
Vd =−104
1.01×105 +104 ×1V=−90.09mV
Inverting Amplifier
VoVi
=−ARf
A+1( )Ri + Rf
⇒VdVi
=−Rf
A+1( )Ri + Rf
Let Vi =1V , Ri =1kΩ , Rf =10kΩ , A=106.
Vo =−1010
1.000001×109 +104 ×1V=−9.999V
Vd =−104
1.000001×109 +104 ×1V=−9.999μV
Inverting Amplifier
VoVi
=−ARf
A+1( )Ri + Rf
⇒VdVi
=−Rf
A+1( )Ri + Rf
Let A→ ∞. limA→ ∞
VoVi
=−Rf
Ri , lim
A→ ∞
VdVi
=0
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin, Engineering Circuit Analysis, Sixth Edition.
Copyright ©2002 McGraw-Hill. All rights reserved.
(a) Electrical symbol for the op amp. (b) Minimum required connections to an op amp.
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin, Engineering Circuit Analysis, Sixth Edition.
Copyright ©2002 McGraw-Hill. All rights reserved.
Op amp connected as an
Inverting amplifier.
Output characteristics.
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin, Engineering Circuit Analysis, Sixth Edition.
Copyright ©2002 McGraw-Hill. All rights reserved.
(c)
(a) An op amp used to construct a noninverting amplifier circuit. (b) Circuit with currents and voltages labeled. (c) Output characteristics.
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin, Engineering Circuit Analysis, Sixth Edition.
Copyright ©2002 McGraw-Hill. All rights reserved.
Basic summing amplifier circuit with three inputs.
Fig. 6.9 Basic difference amplifier.
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin, Engineering Circuit Analysis, Sixth Edition.
Copyright ©2002 McGraw-Hill. All rights reserved.
Basic difference amplifier.
Fig. 6.14 A more detailed model for the op amp.
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin, Engineering Circuit Analysis, Sixth Edition.
Copyright ©2002 McGraw-Hill. All rights reserved.
A more detailed model for the op amp.
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin, Engineering Circuit Analysis, Sixth Edition.
Copyright ©2002 McGraw-Hill. All rights reserved.
Inverting amplifier circuit drawn using detailed op amp model.
W.H. Hayt, Jr., J.E. Kemmerly, S.M. Durbin, Engineering Circuit Analysis, Sixth Edition.
Copyright ©2002 McGraw-Hill. All rights reserved.
Output-input characteristics of a real op amp circuit, showing the linear and saturation regions of operation.