Posted: March 13th, 2023
Report on one of the topics from the list below and explain in your OWN words its basic operation, and uses. Identify which basic operational amplifier configuration is being used in the application (inverting, non-inverting or voltage divider) and which gain equation is needed for the application.
10th ed.
Chapter 13
Basic Op-Amp Circuits
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
10th ed.
◆ Describe and analyze the operation of several types of
comparator circuits
◆ Describe and analyze the operation of several types of
summing amplifiers
◆ Describe and analyze the operation of integrators and
differentiators
◆ Troubleshoot op-amp circuits
Objectives:
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparators
A comparator is a specialized nonlinear op-amp circuit that compares two input voltages and produces an output state that indicates which one is greater. Comparators are designed to be fast and frequently have other capabilities to optimize the comparison function.
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparators
A comparator is a specialized nonlinear op-amp circuit that compares two input voltages and produces an output state that indicates which one is greater. Comparators are designed to be fast and frequently have other capabilities to optimize the comparison function.
An example of a comparator application is shown. The circuit detects a power failure in order to take an action to save data. As long as the comparator senses Vin, the output will be a dc level.
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Electronic Devices
Comparator with Hysteresis
Sometimes the input signal to a comparator may vary due to noise superimposed on the input. The result can be an unstable output. To avoid this, hysteresis can be used.
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparator with Hysteresis
Sometimes the input signal to a comparator may vary due to noise superimposed on the input. The result can be an unstable output. To avoid this, hysteresis can be used.
Hysteresis is incorporated by adding regenerative (positive) feedback, which creates two switching points: the upper trigger point (UTP) and the lower trigger point (LTP). After one trigger point is crossed, it becomes inactive and the other one becomes active.
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparator with Hysteresis
A comparator with hysteresis is also called a Schmitt trigger. The trigger points are found by applying the voltage-divider rule:
and
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparator with Hysteresis
A comparator with hysteresis is also called a Schmitt trigger. The trigger points are found by applying the voltage-divider rule:
and
Example:
What are the trigger points for the circuit if the maximum output is ±13 V?
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparator with Hysteresis
A comparator with hysteresis is also called a Schmitt trigger. The trigger points are found by applying the voltage-divider rule:
and
Solution:
Example:
What are the trigger points for the circuit if the maximum output is ±13 V?
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparator with Hysteresis
A comparator with hysteresis is also called a Schmitt trigger. The trigger points are found by applying the voltage-divider rule:
and
Solution:
Example:
What are the trigger points for the circuit if the maximum output is ±13 V?
= 2.28 V
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparator with Hysteresis
A comparator with hysteresis is also called a Schmitt trigger. The trigger points are found by applying the voltage-divider rule:
and
Solution:
Example:
What are the trigger points for the circuit if the maximum output is ±13 V?
= 2.28 V
By symmetry, the lower trigger point = -2.28 V
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Output Bounding
Some applications require a limit to the output of the comparator (such as a digital circuit). The output can be limited by using one or two zener diodes in the feedback circuit.
The circuit shown here is bounded as a positive value equal to the zener breakdown voltage.
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Electronic Devices
Comparator Applications
A comparator with hysteresis can produce a pulse with a variable duty cycle. For the circuit shown, Vout(max) ranges from 0 V to +5 V because of the GND and VDD connections on the LM311.
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparator Applications
A comparator with hysteresis can produce a pulse with a variable duty cycle. For the circuit shown, Vout(max) ranges from 0 V to +5 V because of the GND and VDD connections on the LM311.
The input is the red triangle wave (0 to 4 V). The duty cycle is varied with R2.
With R2 set to 100%, a 50% duty cycle is the result.
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
Comparator Applications
A comparator with hysteresis can produce a pulse with a variable duty cycle. For the circuit shown, Vout(max) ranges from 0 V to +5 V because of the GND and VDD connections on the LM311.
The input is the red triangle wave (0 to 4 V). The duty cycle is varied with R2.
With R2 set to 5%, a short pulse is the result.
Copyright © 2018 Pearson Education, Inc. All Rights Reserved
Electronic Devices
SOLUTION
The basic operation of an integrator is to output a voltage that is proportional to the input voltage’s time integral. When a voltage is applied to the input of the integrator, the capacitor charges or discharges depending on the polarity of the input voltage. The capacitor’s charge or discharge rate is determined by the input voltage and the capacitor’s value. The operational amplifier adjusts its output voltage to ensure that the capacitor’s voltage follows the input voltage, which results in the output voltage being proportional to the input voltage’s time integral.
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