BS CpE 3rd Year
Linear and Non – Linear
Applications of Operational
Amplifiers
WMSU
Presented by:
What is Operational
Amplifiers?
Introduction to Operational Amplifiers
 Overview of Op-Amps
• Operational Amplifiers (Op Amps) are versatile electronic devices used in
various applications, including signal processing, filtering, and mathematical
operations.
• They are designed to amplify voltage signals and can perform a range of
functions such as addition, subtraction, integration, and differentiation.
• Op amps are widely used in analog circuits due to their high gain, high input
impedance, and low output impedance.
Basic Structure Diagram
Basic Structure and Function of an
Op-Amp
 Structure:
- Input Terminals: Two inputs, inverting (-) and non-inverting (+).
- Output Terminal: Delivers the amplified output.
- Power Supply: Typically requires dual power supply (positive and negative voltage).
- Feedback Network: Often used to control gain and stability.
 Function:
• The op-amp amplifies the difference between the voltages at its two input
terminals.
• The gain of the op-amp can be configured using external resistors in a feedback
loop.
• Ideal op-amps assume infinite gain, infinite input impedance, and zero output
impedance.
Linear and a Non-Linear Behavior in
Op-Amps
Introduction to Linear vs Non-Linear Behavior
in Op-Amps
 Linear Behavior:
• Op-amps operate in linear mode under certain conditions, where the output is directly
proportional to the input voltage difference.
• Common linear applications include amplifiers, filters, and integrators.
• Linear operation is maintained within a specified range of input voltages.
 Non-Linear Behavior:
• Non-linear behavior occurs when the op-amp is driven beyond its limits or when specific
configurations (like comparators) are used.
• Non-linear applications include signal clipping, oscillators, and waveform generators.
• In non-linear operation, the output does not maintain a direct proportionality to the input,
leading to saturation and distortion.
Linear Applications of
Op-Amps (1)
Voltage Follower (Buffer)
•
A voltage follower (also called a buffer amplifier) is
an operational amplifier (op-amp) configuration
where the output voltage follows the input voltage,
meaning the output is equal to the input. The key
feature is that it has unity gain (gain = 1), meaning
it doesn’t amplify the signal but provides high input
impedance and low output impedance.
 How It Works:
•
The input signal is applied to the non-inverting
input of the op-amp, and the output is directly
connected back to the inverting input, creating a
feedback loop.
•
This configuration ensures the output voltage
matches the input voltage.
 Uses:
•
Impedance matching: It isolates different stages
of a circuit without loading down the previous
stage, as it provides high input impedance and low
output impedance.
•
Signal buffering: It ensures signal integrity when
transmitting weak signals over long distances or
between components.
•
Driving capacitive loads: It stabilizes circuits with
high capacitance by buffering the signal.
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Inverting Op-Amp
• The most distinctive feature of an
inverting op-amp is its input
configuration, where the signal is
applied to the inverting (-) input
terminal. The output voltage is
therefore inverted with respect to
the input signal.
 Uses:
• Inverting op-amps are used in
numerous applications, including
inverting
amplifier
circuits,
summing
amplifiers,
and
differential amplifiers.
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Non-inverting Op-Amp
• The non-inverting op-amp
configuration features the input
signal applied to the non-inverting
(+) input terminal.
 Uses:
• Non-inverting op-amps are used in
applications where maintaining
signal phase is critical, such as
voltage followers, non-inverting
amplifier circuits, and buffer
amplifiers. The non-inverting
configuration is advantageous for
applications that require signal
amplification without introducing
phase inversion.
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Summing Amplifier
•
A summing amplifier is a type of operational amplifier (opamp) circuit that outputs the weighted sum of multiple input
signals. It's commonly used in analog computing, audio
mixing, and signal processing.
 How it works:
•
The circuit adds together the input voltages after applying a
negative gain. The output voltage is proportional to the
weighted sum of the input voltages.
 Uses:
•
Audio Mixing: Summing amplifiers are used in audio mixers
to combine multiple audio signals (such as from different
instruments or microphones) into a single output signal.
•
Digital-to-Analog Conversion (DAC): In digital-to-analog
converters, summing amplifiers combine different weighted
binary input signals to produce an analog output.
•
Signal Processing: Summing amplifiers are used in analog
computers or signal processing circuits to add multiple
signals or perform weighted sum operations for filtering,
modulation, and other signal manipulations.
•
Control Systems: They are used in control systems to
combine multiple error signals or inputs to control a system’s
behavior or make decisions.
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Linear Applications of
Op-Amps (2)
Differential Amplifier
• The differential amplifier is a voltage
subtractor circuit which produces an output
voltage proportional to the voltage difference
of two input signals applied to the inputs of
the inverting and non-inverting terminals of
an operational amplifier.
• A differential amplifier is an electronic device
that amplifies the difference between two
input voltage signals while rejecting any
signals that are common to both inputs. This
characteristic makes it particularly useful in
various applications, such as in operational
amplifiers and audio equipment.
Use: It’s used in things like microphones,
where it listens to sounds and helps pick out
the important noise, like someone talking,
while ignoring background sounds.
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Integrator Amplifier
• is an operational amplifier circuit that performs the
mathematical operation of Integration, that is we
can cause the output to respond to changes in the
input voltage over time as the op-amp integrator
produces an output voltage which is proportional
to the integral of the input voltage.
• is an electronic circuit that performs mathematical
integration on an input signal, essentially
producing an output voltage that represents the
accumulated value of the input over time.
Use: It’s used in things like sound systems, where
it helps create nice, smooth sounds by combining
different noises together.
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Differentiator Amplifier
•
A differentiator amplifier is an electronic circuit that
outputs a voltage proportional to the rate of change of
its input signal. In simpler terms, it amplifies how
quickly the input voltage is changing, making it useful
in various applications where detecting changes over
time is important, such as in signal processing and
control systems.
•
The typical setup for a differentiator amplifier involves
an operational amplifier (op-amp) with a capacitor in
the input path and a resistor in the feedback loop. This
configuration allows the circuit to respond quickly to
changes in the input signal. When a voltage is applied,
the capacitor's ability to charge and discharge causes
the output to reflect the derivative of the input voltage.
Use: It’s used in devices that need to measure speed or
change, like in robots that need to know how quickly they
are moving.
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 Importance
• The importance of linearity is in its ability to simplify analysis,
improve accuracy, enhance stability, and ensure reliable
performance across a wide range of applications.
 Summary of Linear applications
• Linear applications make it easier to design, analyze, and use
various technologies by providing predictable and reliable
outputs based on inputs. This makes them essential in
everyday devices and complex systems alike.
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Non-Linear Applications of
Op-Amps (1)
Non-Linear Applications of Operational
Amplifiers
 Non-Linear Operational Amplifier
• It isn’t just a standard amplifier
• Is an amplifier whose output isn’t directly proportional to its input.
 Common Non-Linear Op Amp Circuit
•
•
•
•
•
Comparator Circuits
Oscillators
Wave Shaping Circuits
Analog to Digital Converters
Peak Detectors
 Role of Non-Linear Op Amp in Circuit Design.
• It can amplify the difference between two input signals in a comparator circuit.
• In oscillator circuit, non-linear op amp can be used to generate a steady, periodic waveform
from little to no input.
• It is also useful in communication system.
Comparator
• Is an electronic circuit, which compares two inputs
that are applied to it and produces an output.
• The output value of the comparator indicates which of
the inputs is greater and lesser.
• It consists of two-terminal
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Types of Comparator
 Inverting Comparator
• Is an op-amp based comparator for
which a reference voltage is applied to
its non-inverting terminal and the input
voltage is applied to its inverting
terminal.
 Non-Inverting Comparator
• Is an op-amp based comparator for
which a reference voltage is applied to
its inverting terminal and the input
voltage is applied to its non-inverting
terminal.
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Logarithmic
 Logarithmic Amplifier
•
Logarithmic amplifier or log amplifier, is an
electronic circuit that produces an output that is
proportional to the logarithm of the applied
input.
•
It produces a voltage at the output, which is
proportional to the logarithm of the voltage
applied to the resistor connected to its inverting
terminal.
 Anti-Logarithmic Amplifier
•
Anti-Logarithmic Amplifier or anti-log amplifier, is
an electronic circuit that produces an output that
is proportional to the anti-logarithm of the
applied input.
•
It produces a voltage at the output, which is
proportional to the anti-logarithm of the voltage
that is applied to the diode connected to its
inverting terminal.
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Precision Rectifier
•
Is an electronic circuit which produces AC signal or a pulsated AC signal
 Types of Precision Rectifier
 Half Wave Rectifier
• A rectifier that produces positive half
cycles at the output for one half cycle
of the input and zero output for the
other half cycle of the input.
 Full Wave Rectifier
• It produces half cycles at the output for
the both half cycles of the input.
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Wave Shaping Circuits
• Is an electronic circuit, which produce the desired shape at the output from the
applied input wave form.
• It attenuates the applied wave
• It also alters the dc level of the applied wave
 Two Types of Wave Shaping Circuits
 Clampers
• is an electronic circuit that
produces an output, which is
similar to the input but with a shift
in the DC level.
• the output of a clamper is an exact
replica of the input.
• Clampers are used to introduce or
restore the DC level of input signal
at the output.
• It has two types of clampers,
namely; Positive Clamper, and
Negative Clamper
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 Clippers
• Is an electronic circuit that produces an output by removing
a part of the input above or below a reference value.
- They eliminate the unwanted noise present in the
amplitude of an AC signal.
- It can be classified into two types based on the clipping
portion of the input,
includes positive clipper, and
negative clipper.
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Two Types of Clipping
 Positive Clipper
• a clipper that clips only the positive
portion(s) of the input signal
 Negative Clipper
• A clipper that clips only the negative
portion of the input signal.
• Can obtain the circuit just by reversing
the diode and taking the reverse
polarity of the reference voltage.
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Schmitt Trigger
• A Schmitt Trigger is a type of comparator circuit which
flips the output according to the input signal level
compared to a reference level.
• it adds hysteresis to the input-output relationship that is
smoothing out the output in the presence of a
fluctuating input.
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Types of Schmitt Trigger
 Inverting Schmitt Trigger
• The input is applied to the inverting
terminal of the op-amp and positive
feedback is applied from the output to
the input.
• If the applied voltage Vin is greater
than Vi the output of the circuit will be
low
 Non-Inverting Schmitt Trigger
• The input signal is connected to the
non-inverting terminal of the op-amp.
• The output will be high when the
voltage V is greater than zero and the
output will be low when voltage V is
less than zero.
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Non-Linear Applications of
Op-Amps (2)
Peak Detector
• Peak detector circuits are
used to determine the peak
(maximum) value of an input
signal. It stores the peak value
of input voltages for infinite
time duration until it comes to
reset condition. The peak
detector circuit utilizes its
property of following the
highest value of an input
signal and storing it.
The figure shows the circuit of a basic positive peak
detector.
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Astable Multivibrator Using Op-Amp
• An op-amp astable multivibrator
circuit is constructed by adding
external components to zero
crossing detector or Schmitt
trigger circuit. An astable
multivibrator is a non-linear circuit
configuration using op-amp (the
output changes non-linearly with
respect to the input), which
generates square waves without
any external triggering.
The circuit is a Schmitt trigger configuration, which
has a feedback connection and includes an input
capacitor at the inverting input terminal.
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Op-amp Monostable Multivibrator
• A monostable multivibrator, like
the name suggests, is a circuit
that has one stable output state.
Its normal output voltage may be
high or low, and it stays in that
state until triggered. When a
triggering pulse is applied, the
output switches to the opposite
state for a time that is dependent
on the RC components of the
circuit.
The circuit of a typical monostable multivibrator
using an op-amp.
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Bistable Multivibrator
• Bistable Multivibrators operate in
a similar fashion to flip-flops
producing one of two stable
outputs which are the
complement of each other.
Bistable Multivibrators have TWO
stable states (hence the name:
“Bi” meaning two) and maintain a
given output state indefinitely
unless an external trigger is
applied forcing it to change state.
The Bistable Multivibrator circuit above is stable
in both states, either with one transistor “OFF”
and the other “ON” or with the first transistor
“ON” and the second “OFF”.
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 Importance
• Non-linearity is vital in advanced signal processing because it accurately models physical
systems, enhances performance in tasks like noise reduction and feature extraction, and allows
non-linear adaptive algorithms, such as neural networks, to better handle complex signal
patterns.
 Summary of Non-Linear Applications of Op-Amps:
• Used as comparators, integrators, differentiators, and summing amplifiers for various signal
processing tasks.
 Peak Detector
• Captures and holds the peak voltage of an input signal, essential for measuring signal levels in
audio and RF applications.
 Multivibrators:
• Astable - Generates continuous square waves for clock pulses.
• Monostable - Produces single output pulses in response to triggers, used in timers.
• Bistable - Acts as a flip-flop for binary data storage in digital circuits.
• These applications enhance signal conditioning, timing, and control in electronic systems,
enable accurate data processing, and are vital for measurement and monitoring functions, t hus
improving the overall performance of various technological domains.
References:
I. Introduction to Operational Amplifiers
• https://www.electronics-tutorials.ws/opamp/opamp_1.html
• https://www.tutorialspoint.com/linear_integrated_circuits_applications/linear_integrated
_circuits_applications_op_amp_applications.htm
II. Linear Applications of Op-Amps (1)
• Reference: https://ultimateelectronicsbook.com/op-amp-voltagebuffer/#:~:text=A%20voltage%20buffer%2C%20also%20known,circuits%20with%20closed
%2Dloop%20feedback.Inverting and Non-Inverting Op-Amp
• Reference: https://resources.pcb.cadence.com/blog/2024-inverting-vs-non-inverting-opamp-a-comparison
• https://www.electronics-tutorials.ws/opamp/opamp_4.html
III. Linear Application of Op-Amps (2)
• https://www.electronics-tutorials.ws/opamp/opamp_7.html
• https://www.electronics-tutorials.ws/opamp/opamp_6.html
• https://www.electronics-tutorials.ws/opamp/opamp_5.html
References:
•
•
•
•
•
IV. Non-Linear Applications of Op-Amps (1)
https://www.studysmarter.co.uk/explanations/physics/electricity-and-magnetism/nonlinear-op-amp/
https://www.tutorialspoint.com/linear_integrated_circuits_applications/linear_integrate
d_circuits_applications_comparators.htm
https://www.tutorialspoint.com/linear_integrated_circuits_applications/linear_integrate
d_circuits_applications_log_and_anti_log_amplifiers.htm
https://www.tutorialspoint.com/linear_integrated_circuits_applications/linear_integrate
d_circuits_applications_rectifiers.htm
https://www.tutorialspoint.com/linear_integrated_circuits_applications/linear_integrate
d_circuits_applications_clippers.htm
V. Non-Linear Applications of Op-Amps (2)
• https://www.electronics-tutorials.ws/waveforms/bistable.html
• https://www.electronicshub.org/non-linear-op-amp-circuits/
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