The document discusses operational amplifiers and their applications. It begins with an introduction to op amps and the 741 op amp circuit. It then describes the ideal op amp model and various op amp configurations like inverting, non-inverting, integrator, and differentiator. It also discusses bistable circuits and their application in comparators for generating square waves. The document contains circuit diagrams and descriptions of each op amp application.

1. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
Operational-Amplifier
and its Applications
Course: 90 INAC-L&X
AT-15
Prof.Satheesh Monikandan B
sathy24@gmail.com

2. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
Outline
• Introduction
• The 741 Op-Amp Circuit
• The ideal Op Amp
• The inverting configuration
• The non-inverting configuration
• Integrator and differentiator

3. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
Introduction
• Analog ICs include operational amplifiers, PLL,
etc.
• A complete op amp is realized by combining
analog circuit building blocks.
• The bipolar op-amp has the general purpose
variety and is designed to fit a wide range of
specifications.
• The terminal characteristics is nearly ideal.

4. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
The 741 Op-Amp Circuit
• General description
• The input stage
• The intermediate stage
• The output stage
• The biasing circuits
• Device parameters

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BLOCK DIAGRAM

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General Description
• 20 transistors, few resistors and only one
capacitor
• Two power supplies
• Short-circuit protection

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PIN DIAGRAM

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ARCHITECTURE

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The Ideal Op Amplifier
Symbol for the op amp

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The Ideal Op Amplifier
The op amp shown connected to dc power supplies.

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Characteristics of the Ideal Op
Amplifier
• Differential input resistance is infinite.
• Differential voltage gain is infinite.
• CMRR is infinite.
• Bandwidth is infinite.
• Output resistance is zero.
• Offset voltage and current is zero.

12. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
Equivalent Circuit of the Ideal Op
Amp

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FREQUENCY RESPONSE

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TRANSFER CHARACTERISTICS

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The Inverting Configuration
The inverting closed-loop configuration.
Virtual ground.

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The Inverting Configuration

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The Inverting Configuration

18. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
The Inverting Configuration
• Shunt-shunt negative feedback
• Closed-loop gain depends entirely on passive
components and is independent of the op
amplifier.
• Engineer can make the closed-loop gain as
accurate as he wants as long as the passive
components are accurate.

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I/O WAVEFORM

20. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
The Non-inverting Configuration
The non-inverting configuration.
Series-shunt negative feedback.

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The Non-inverting Configuration

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I/O WAVEFORM

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The Voltage follower
(a) The unity-gain buffer or follower amplifier.
(b) Its equivalent circuit model.

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I/O WAVEFORM

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The Weighted Summer

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A Single Op-Amp Difference
Amplifier
Linear amplifier.
Theorem of linear
Superposition.

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A Single Op-Amp Difference
Amplifier
Application of superposition
Inverting configuration
vo1=−
R2
R1
vI1

28. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
A Single Op-Amp Difference
Amplifier
Application of superposition.
Non-inverting configuration.
vo2=(1+
R2
R1
)(
R4
R4 +R3
v） I2

29. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
Integrators
The inverting configuration with general impedances in
the feedback and the feed-in paths.

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The Inverting Integrators
The Miller or inverting integrator.

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Frequency Response of the
integrator

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I/O WAVEFORM

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The op-amp Differentiator

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The op-amp Differentiator
Frequency response of a differentiator with a time-constant CR.

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I/O WAVEFORM

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Bistable Circuit
The bistable circuit (positive
feedback loop)
The negative input terminal of the op
amp connected to an input signal vI.
v+ =vo
R1
R1 +R2
=vo β

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Bistable Circuit
The transfer characteristic of
the circuit in (a) for increasing vI.
Positive saturation L+ and
negative saturation L-
VTH =L+ β

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Bistable Circuit
The transfer characteristic
for decreasing vI.
VTL=L− β

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Bistable Circuit
The complete transfer characteristics.

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Application of Bistable Circuit as a
Comparator
• Comparator is an analog-circuit building block
used in a variety applications.
• To detect the level of an input signal relative to a
preset threshold value.
• To design A/D converter.
• Include single threshold value and two threshold
values.
• Hysteresis comparator can reject the interference.

41. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
Application of Bistable Circuit as a
Comparator
Block diagram representation and transfer characteristic for a
comparator having a reference, or threshold, voltage VR.
Comparator characteristic with hysteresis.

42. 03/07/15 Prof.Satheesh MB, INA, Ezhimala
Application of Bistable Circuit as a
Comparator
Illustrating the use of
hysteresis in the
comparator
characteristics as a
means of rejecting
interference.

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Generation of Square Waveforms
The circuit obtained when the bistable multi-vibrator is
implemented with the positive feedback loop circuit.