inverting and non inverting amplifier lab experiment

Academia.edu no longer supports Internet Explorer.

To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to  upgrade your browser .

Enter the email address you signed up with and we'll email you a reset link.

• We're Hiring!
• Help Center

EEEB111 LAB REPORT EXPERIMENT 7: INVERTING AND NON-INVERTING AMPLIFIERS

Related Papers

Sandeep Goyal

Jose Arturo Mendez

Satyamshree Moharana

Mohiuddin Mahbub

Manthan Manavadaria

Dumitru Costin

sarankumar mr

jhovanny rodriguez

Fuad Ilhamz

While in the process of reviewing Texas Instruments applications notes, including those from Burr-Brown – I uncovered a couple of treasures, this handbook on op amp applications and one on active RC networks. These old publications, from 1963 and 1966, respectively, are some of the finest works on op amp theory that I have ever seen. Nevertheless, they contain some material that is hopelessly outdated. This includes everything from the state of the art of amplifier technology, to the parts referenced in the document – even to the symbol used for the op amp itself: These numbers in the circles referred to pin numbers of old op amps, which were potted modules instead of integrated circuits. Many references to these numbers were made in the text, and these have been changed, of course. In revising this document, I chose to take a minimal approach to the material out of respect for the original author, – Thomas R. Brown, leaving as much of the original material intact as possible while making the document relevant to present day designers. There were some sections that were deleted or substantially changed: • = " Broadbanding " operational amplifier modules – replaced with discussion of uncompensated operational amplifiers. • = Open loop applications and Comparators – Applications showing an operational amplifier used open loop, as a comparator have been deleted. At the time of original publication, there were no dedicated comparator components. Good design techniques now dictate using a comparator instead of an operational amplifier. There are ways of safely using an operational amplifier as a comparator – if the output stage is designed to be used that way-as in a voltage limiting operational amplifier – or if clamping is added externally that prevents the output from saturating. These applications are shown. • = Testing Operational Amplifiers – a section that had become hopelessly outdated. Testing techniques are now tailored to the individual amplifier, to test for parameters important to its intended purpose or target end equipment.

Loading Preview

Sorry, preview is currently unavailable. You can download the paper by clicking the button above.

RELATED PAPERS

raj mangave

HARISH BHATIA

Pramod Bokde

Dr. Ashok Chhetry

Gary Hebert

Giacomo Torzo

Mr.SAM JAIKUMAR.S

MİZGİN AKGÜL

Tobías Lifschitz

Francisco Glover

1975 IEEE International Solid-State Circuits Conference. Digest of Technical Papers

Johan Huijsing

Amitava Ghorai

Mohideen Kader

Karthik Vinayaka

Santiago Prieto

nura muhammad

Dr.Saravanan Govindarajan

International Journal of Advanced Science Computing and Engineering

Prof. Vijay Aithekar

Princess Balunes

Analog Integrated Circuits and Signal Processing

Steve Deweerth

Analog Circuits and Signal Processing

Mohamed Albanna

IEEE Journal of Solid-State Circuits

RELATED TOPICS

•   We're Hiring!
•   Help Center
• Find new research papers in:
• Health Sciences
• Earth Sciences
• Cognitive Science
• Mathematics
• Computer Science
• Academia ©2024

• Network Sites:
• Technical Articles
• Market Insights

• Or sign in with
• iHeartRadio

• Analog Lab - Non-inverting Amplifier

Join our Engineering Community! Sign-in with:

• DIY Electronics Projects

Analog IC Projects

• Analog Lab - Introduction
• Analog Lab - Voltage Comparator
• Analog Lab - Precision Voltage Follower Using an Op Amp
• Analog Lab - High-impedance Voltmeter
• Analog Lab - Op Amp Integrator
• Analog Lab - 555 Oscillator (Astable Multivibrator)
• Analog Lab - 555 Ramp Signal Generator
• Analog Lab - PWM Power Controller
• Analog Lab - Class B Audio Amplifier

In this hands-on electronics experiment, you will build a programmable non-inverting amplifier and learn how to use the negative feedback of an operational amplifier to control the gain.

Project overview.

The non-inverting amplifier with an adjustable gain is one of the most useful circuits you can build with an operational amplifier (op amp) . As illustrated in Figure 1, the op amp uses a resistor divider ( potentiometer , R 2 ) to provide negative feedback .  

Figure 1. Schematic diagram of the op amp non-inverting amplifier circuit.

As we will demonstrate, this divided negative feedback is key to the operation of the non-inverting amplifier.

Parts and Materials

• Op amp, model 1458 or 353, recommended
• Three 6 V batteries or an 18 V power supply
• Two 10 kΩ potentiometers, linear taper

Learning Objectives

• How to use an op amp as a single-ended amplifier
• How to use divided negative feedback

Theory of Operation

This circuit differs from the voltage follower project in only one respect, the output voltage is fed back to the inverting (-) input through a voltage-dividing potentiometer rather than being directly connected. With only a fraction of the output voltage fed back to the inverting input, the op amp will output a corresponding multiple of the voltage sensed at the noninverting (+) input to keep the input differential voltage near zero.

In other words, the op amp will now function as an amplifier with a controllable voltage gain, that gain is established by the position of the feedback potentiometer (R 2 ).

Instructions

Step 1:  Build the non-inverting amplifier circuit of Figure 1. A breadboard implementation of this circuit is illustrated in Figure 2.

Figure 2. Breadboard implementation of the op amp non-inverting amplifier.

Step 2:  Set R 2 to approximately mid-position. This should give a voltage gain of about 2. See the derivation of the non-inverting amplifier gain equation (which is discussed later in this chapter) to understand why this is true.

Step 3:  Measure both the input and output voltage for several positions of the input potentiometer R 1 .

Step 4:  Move R 2 to a different position and re-take voltage measurements for several positions of R 1 . For any given R 2 position, the ratio between output and input voltage should be the same. The ability to leverage an op amp in this fashion to create an amplifier with controllable voltage gain makes this circuit an extremely useful one.

You will also notice that the input and output voltages are always positive with respect to the ground . Since the output voltage increases in a positive direction for a positive increase of the input voltage, this amplifier is referred to as non-inverting. If the output and input voltages were related to one another in an inverse fashion (i.e. positive increasing input voltage results in positive decreasing or negative increasing output), then the amplifier would be known as an inverting type.

Step 5:  Try adjusting R 2 for maximum and minimum voltage gain. What is the minimum voltage gain attainable with this amplifier configuration? Why do you think this is?

Op Amp Non-inverting Amplifier Gain Equation

Let's derive the non-inverting amplifier gain equation using the schematic of Figure 3, which has distinct resistors, R 1 and R 2 , in the negative feedback path. 

Figure 3. SPICE circuit schematic with node numbers for simulation of the op amp non-inverting amplifier

Beginning from the op amp open-loop gain equation:

$$V_{out} = A \cdot (V_+ - V_-) = A \cdot (V_{in} - V_-)$$

Where A  is the open-loop gain of the op amp, and we are defining the non-inverting op amp input (V + ) as the non-inverting amplifier input, V in .

The relationship of V -  to V out  is given by the resistive voltage divider equation:

$$V_{-} = \left( \frac{R_1}{R_1+R_2} \right) V_{out}$$

Substituting, we get:

$$V_{out} = A\left(V_{in} - \left( \frac{R_1}{R_1+R_2} \right) V_{out} \right)$$

$$V_{out} + A\left( \frac{R_1}{R_1+R_2} \right) V_{out} = AV_{in}$$

Dividing both sides of the equation by the open-loop op amp gain, A, results in:

$$V_{out} \left( 1 + A\left( \frac{R_1}{R_1+R_2} \right) \right) = AV_{in}$$

Now, we will make an approximation to simplify the remaining analysis. The op amp open-loop gain, A, is typically a very large number, at least 10,000, and often much more. So, we will make the following approximation:

$$\frac{1}{A} \approx 0$$

This reduces our equation to:

$$V_{out} \left( \frac{R_1}{R_1+R_2}\right) = V_{in}$$

With some simple rearranging of terms, we arrive at our non-inverting amplifier gain, G:

$$G = \frac{V_{out}}{V_{in}} = 1 + \frac{R_2}{R_1}$$

SPICE Simulation of the Non-inverting Amplifier

The circuit schematic of Figure 3 uses a dependent voltage source (E 1 ) to simulate an op amp. 

Netlist (make a text file containing the following text, verbatim):

With R 1 and R 2 set equally to 5 kΩ in the simulation, it mimics the feedback potentiometer of the real circuit at mid-position (50%). To simulate the potentiometer at the 75% position, set R 2 to 7.5 kΩ and R 1 to 2.5 kΩ.

Related Content

Learn more about the fundamentals behind this project in the resources below.

Calculators:

• Op Amp Voltage and Gain Calculator
• Inverting Op Amp Resistor Calculator
• Non-inverting Op Amp Resistor Calculator
• Voltage Divider Calculator
• Operational Amplifiers
• Inverting and Non-inverting Op Amp Voltage Amplifier Circuits Worksheet
• Basic Operational Amplifier Worksheet
• Op Amp Circuits Worksheet
• Textbook Index

Lessons in Electric Circuits

Volumes ».

• Direct Current (DC)
• Alternating Current (AC)
• Semiconductors
• Digital Circuits
• EE Reference

Chapters »

• 1 Introduction to Electronics Projects
• 2 Basic Projects and Test Equipment
• 3 DC Circuit Projects
• 4 AC Circuit Projects
• 5 Discrete Semiconductor Circuit Projects

Pages »

• 7 Digital IC Projects
• 8 555 Timer Circuit Projects
• 9 Contributor List
• Advanced Textbooks Practical Guide to Radio-Frequency Analysis and Design
• Designing Analog Chips
• Silicon Labs Bluetooth Solutions
• Driving Piezoelectric Actuators with Linear Amplifiers
• Innovative Bluetooth Technology with Silicon Labs
• Smart Bench Essentials and Remote Lab Access
• Introduction to the CFA: Current-Feedback Amplifiers vs. Voltage-Feedback Amplifiers
• Renesas Lab on the Cloud: Evaluate Boards Remotely through an Intuitive GUI

You May Also Like

What is USB 3.0? High-Speed Routing Guidelines

In Partnership with Autodesk

Faster, Higher, Stronger: Reflections on Olympics Technology Past and Present

by Duane Benson

Why Class D Amplifiers Need Anti-Parallel Diodes

by Dr. Steve Arar

Researchers Take Inspiration From Superman’s X-Ray Vision for Imaging Chip

by Aaron Carman

NXP Launches Scalable Wireless MCU Series at Embedded World

Welcome Back

Don't have an AAC account? Create one now .

Forgot your password? Click here .

• Trending Categories

• Selected Reading
• UPSC IAS Exams Notes
• Developer's Best Practices
• Questions and Answers
• Effective Resume Writing
• HR Interview Questions
• Computer Glossary

Inverting and Non-Inverting Operational Amplifiers

An operational amplifier is a three-terminal device consisting of two high impedance input terminals, one is called the inverting input denoted by a negative sign and the other is the non-inverting input denoted with a positive sign. The third terminal is the output of the Op-Amp.

Inverting Operational Amplifier

In the inverting operational amplifier circuit, the signal is applied at the inverting input and the non-inverting input is connected to the ground. In this type of amplifier , the output is 180⁰ out of phase to the input, i.e. when positive signal is applied to circuit, the output of the circuit will be negative. By assuming the Op-Amp is ideal, then the concept of virtual short can be applied at the input terminals of the Op-Amp. So that voltage at the inverting terminal is equal to the voltage at non-inverting terminal.

Applying KCL at inverting node of Op-Amp

$$\mathrm{\frac{0-V_{in}}{R_{1}}+\frac{0-V_{out}}{R_{2}}=0}$$

$$\mathrm{Voltage\:Gain(A_{v})=\frac{V_{out}}{V_{in}}=-\frac{R_{2}}{R_{1}}}$$

Non-Inverting Operational Amplifier

When the signal is applied at the non-inverting input, the resulting circuit is known as Non-Inverting Op-Amp. In this amplifier the output is exactly in phase with the input i.e. when a positive voltage is applied to the circuit, the output will also be positive. By assuming the Op-Amp is ideal, then concept of virtual short can be applied i.e. the voltage at the inverting and non-inverting terminal is equal.

Applying KCL at the inverting node

$$\mathrm{\frac{V_{in}-V_{out}}{R_{2}}+\frac{V_{0}-0}{R_{1}}=0}$$

$$\mathrm{Voltage\:Gain(A_{v})=\frac{V_{out}}{V_{in}}=1+\frac{R_{2}}{R_{1}}}$$

Difference between Inverting and Non-Inverting Op-Amps

• Related Articles
• Difference between Inverting and Non-Inverting Amplifier
• Physical Limitations of Operational Amplifiers
• Inverting signs in array - JavaScript
• Inverting a binary tree in JavaScript
• Inverting slashes in a string in JavaScript
• Inverting all bit values in BitArray in C#
• Explain the HDLC Operational and Non-Operational Modes
• Inverting signs of integers in an array using JavaScript
• Maximum Subarray Sum after inverting at most two elements in C++
• Operational Database
• Operational Amplifier-Basic Concepts and Applications
• Difference between Data Warehouse and Operational Database
• Difference between Operational Database and Data Warehouse?
• Operational modes of 8255
• Operational Efficiency and Its Effect On Working Capital

Kickstart Your Career

Get certified by completing the course