IDEAL OPERATIONAL AMPLIFIER AND OP-AMP CIRCUITS

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CHAPTER 8

• IDEAL OPERATIONAL AMPLIFIER AND OP-AMP CIRCUITS

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Op-amp circuit symbol

• Open loop mode
• Vo Aod ( v2 v1)
• Aod is referred to as the open loop gain.
• Notice that is v2 v1, the open loop gain equals
  to ?

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Final Exam SEM II 2012/2013
An ideal op-amp, was measured in a lab experiment
in open-loop mode. Determine the open loop gain
(Aod) and complete the table below which shows
the results of the experiment.
V1 (1) V2 (2) Vo (3)
-1mV 1mV 1V
-0.5V   -3V
  1V 5V
-0.506 V
0.99 V
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• Op amp can be configured to be used for different
  type of circuit applications
• Inverting Amplifier
• Non inverting Amplifier
• Summing Amplifier
• Integrator
• Differentiator

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• Two main characteristics
• We want the open loop gain to be equal to ? which
  means that v2 v1
• We also want the input resistance to be equal to
  ? , hence there is no current going into the
  op-amp

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Inverting Amplifier
Op-amp as an inverting amplifier
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Exercise 8.3
Gain - (R2 / R1) -(150/12) -12.5
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Can the voltage gain be calculated using the same
formula? Try and use the same method in deriving
Vo/Vi
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Non - Inverting Amplifier
Noninverting amplifier
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Voltage Follower / Buffer Amplifier
Vo Vi Hence, gain 1
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Summing Amplifier
Similarly,
i1 i2 i3 i4 0 0
Example 8.2 Design a summing amplifier as shown
in figure to produce a specific output signal,
such that vo 1.25 2.5 cos ?t volt. Assume the
input signals are vI1 -1.0 V, vI2 0.5 cos ?t
volt. Assume the feedback resistance RF 10 k?
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Solution output voltage
 
 
 
 
 
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Other Op-Amp Applications
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Integrator
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Differentiator
EXAMPLE 8.4
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Calculating Gain and Design Questions
NON - INVERTING
INVERTING
Calculating Output and Design Questions
SUMMING AMPLIFIER
INTEGRATOR AMPLIFIER
DIFFERENTIATOR AMPLIFIER
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Calculate the input voltage if the final output,
VO is 10.08 V. 
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What is the value of Vin1 from the figure above?
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Calculate the output voltage, VO if V1 V2 700
mV
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Answering the questions

• There are 5 questions. Answer all.
• Chapter 1 2 will not be in the final exam
• Organize your thoughts. When it is organized, so
  will your workflow.
• Messy work will make the lecturers feel annoyed
  as they have to look for your answers bear in
  mind that lecturer handling one section 50-60
  students each paper has 5 questions
• TOTAL 250 to 300 questions to mark
• Dont leave a question blank just write down
  anything you know that might be related
• Study smart, pray and tawakal.