debraj2020

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OPERATIONAL AMPLIFIER
KAZI NAZRUL UNIVERSITY (B.B COLLEGE CAMPUS)
PRESENTED BY DEBRAJ MAJI
ROLL NO. -1020133200320020
REGISTRATION NO KNU18001208
SESSION SEMESTER I
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CONTENTS

• Introduction
• What is Op-Amp?
• Op-Amp pin Diagram
• Circuit Symbol and internal Circuit
• Characteristics of Op-Amp
• Parameter of Op-Amp
• Op-Amps Configuration
• Inverting Amplifier
• Non-inverting Amplifier
• Buffer
• Summing Amplifier
• Integrator
• Differentiator
• Application of Op-Amp
• References

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INTRODUCTION

• The term operational amplifier denotes a
  special type of amplifier that, by proper
  selection of its external components, could be
  configured for a variety of operations.

HISTORY

• First developed by Karl D. Swartzel jr. in 1941
  with vacuum tube.
• In 1963 Bob Widlar introduces the op-amp that
  was to become the industry standard.

Figure1 Vacuum tube Operational Amplifier
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WHAT IS OP-AMP?

• An Operational Amplifier (Op-Amp) is an
  integrated circuit that uses external voltage to
  amplify the input through a very high gain.
• Op amps are differential amplifiers, and there
  output voltage is proportional to the difference
  of the two input voltages.

Figure2 What an Op-Amp looks like in todays
world
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OP-AMP PIN DIAGRAM
There are 8 pins in a common Op-Amp, like 741
which is used many instructional course.

• Pin1 Offset null
• Pin2 Inverting input terminal
• Pin3 Non-inverting input terminal
• Pin4 -VCC (negative voltage supply)
• Pin5 Offset null
• Pin6 Output terminal
• Pin7 VCC(positive voltage supply)
• Pin8 No connection

Figure3 Pin Diagram of 741 Op-Amp
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CIRCUIT SYMBOL AND INTERNAL CIRCUIT
Figure5 Internal Circuit of Op-Amp
Figure4 Circuit Symbol of Op-Amp
Figure shows the symbol of Op-Amp. The power
supply at vs VS- to make it works. The input
terminal defined by the - symbol are
designated inverting non-inverting. The voltage
w.r.t ground denoted as V V- and output
voltage as Vout.
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CHARACTERISTICS OF OP-AMP
IDEAL
REAL

• Infinite input impedance
• Zero output impedance
• Zero common-mode gain or, infinite common mode
  rejection ratio
• Infinite open loop gain
• Infinite bandwidth
• Characteristics independent of temperature

• The input impedance between 150 k? to a few
  hundred mega ohm
• The output impedance lies in the range 0.75? to
  100?
• Voltage gain is typically 10 to 10
• Characteristics change with temperature very
  slightly

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PARAMETER OF OP-AMPS

• input offset voltage(Vio)
• A small voltage required
  between the inputs of an operational amplifier to
  make the output zero, is called input offset
  voltage.

• 2mv for 741 IC

• Input offset current(Iio)
• The difference between the
  bias currents at the input terminals of Op-Amps
  is called input offset current

• 200nA for 741 IC

• Input bias current
• Input bias current IB as the
  average value of the base current entering into
  terminal of an op-amp

• 700 nA for 741 IC

• Input Resistance(Ri)
• It is the equivalent
  resistance that can be measured at either
  inverting or non-inverting inputs terminal with
  the other terminal grounded

• 2M? for 741 IC

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• Output Resistance(Ro)
• It is the equivalent resistance that
  can be measured output terminal and ground
  terminal

• 75? for 741IC

• Voltage gain(A)
• Voltage gain is the ratio between
  output voltage and input voltage

• Open loop voltage gain for IC741 is 200,000

• Common Mode Rejection Ratio(CMMR)
• It is define as the ratio of
  differential voltage gain Ad to common voltage
  gain Acm

• 20 dB for 741 IC

• Slew Rate(SR)
• It is defined as the maximum rate
  of change of output voltage

• 0.5 V/us for 741 IC

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OP-AMPS CONFIGURATION

• Inverting Amplifier
• Non- inverting Amplifier
• Summing Amplifier
• Buffer Amplifier
• Integrator
• Differentiator

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INVERTING AMPLIFIER
Figure6 Circuit diagram of inverting amplifier
In Inverting Amplifier configuration the output
voltage 180 degree out of phase with respect to
input voltage (i.e. if you apply positive voltage
, output will be negative)
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N0N-INVERTING AMPLIFIER
Figure7 Circuit diagram of non-inverting
amplifier
In this configuration the output voltage and
input voltage in same phase ( i.e. if you apply
positive voltage, output will be positive)
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BUFFER AMPLIFIER
Figure8 Circuit diagram of Buffer amplifier
In this configuration the output voltage and
input voltage are same in amplitude and phase.
(i.e. if you apply 1V , then output will be 1V)
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SUMMING AMPLIFIER
Figure9 Circuit diagram of summing amplifier
If RF R1R2R3R , then the output voltage is
exactly the inverted algebraic sum of the input
voltages
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INTEGRATOR
Figure10 Circuit diagram of integrator
In this configuration the output voltage is the
integral of input voltage
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DIFFERENTIATOR
Figure11 Circuit diagram of differentiator
In this configuration the output voltage is
proportional to the time derivative of the input
voltage
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APPLICATION OF OP-AMP

• Electrocardiogram(EKG)Amplification
• - Need to measure difference in voltage
  from lead1 and lead2
• - 60Hz interference from electrical
  equipment

• Simple EKG circuit
• - Uses differential amplifier to cancel
  common mode signal and amplify differential mode
  signal

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• Realistic EKG circuit
• - Uses two non-inverting amplifiers to
  amplify voltage from each lead, followed by
  differential amplifier
• - Forms and instrumentation amplifier

• Piezoelectric Transducer
• - Used to measure force and pressure
• - Piezoelectric crystal generate and
  electric charge in response to deformation

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REFERENCES

• Operational Amplifier
• https//en.wikipedia.org/wiki/Operational_amplifie
  r

• Operational Amplifier Application
• https//en.wikipedia.org/wiki/Operational_amplifie
  r_applications

• Fundamental Principles of Electronics by B
  Ghosh

• Jung, Walter G. Op-Amp Applications Handbook .
• Analog Devices , Inc. 2005.

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THANK YOU