90.1.1 - Introduction to Feedback System
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Fundamentals of Feedback Systems
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Welcome class! Today, we're diving into feedback systems. Can anyone tell me what a feedback system is?
Isn't it about sending the output back into the system?
Exactly! Feedback systems sample the output and return it to the input. This can stabilize or further enhance the output signal. A simple way to remember this is: 'Feedback feels.'
What are the main types of feedback?
Great question! There are two main types: negative feedback, which counters changes, and positive feedback, which enhances them.
Can you give me an example of negative feedback?
Absolutely! In a temperature control system, if the temperature rises above a set point, the system will cool down, that's negative feedback at work.
Remember, negative feedback reduces the effect of disturbances, while positive feedback increases it.
Types of Feedback Systems
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Let's explore the types of feedback systems further. How does negative feedback work?
It opposes the original input signal, right?
Exactly! Negative feedback stabilizes the system. For instance, if a signal increases, negative feedback will act to reduce it.
What about positive feedback?
Positive feedback does the opposite—it enhances the signal. Think of a microphone too close to its speaker; it causes a loud screeching noise due to positive feedback.
So, which one is generally more stable?
Negative feedback is usually more stable, while positive feedback can lead to system instability. Remember: 'N for Negative, N for Noisy!'
Transfer Characteristics of Feedback Systems
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Now, let's dive into transfer characteristics. Can someone explain its significance?
Is it about how the input relates to the output?
Precisely! It's vital to understand how feedback can alter the relationship between input and output. The equation S = A(S - βS) summarizes this.
What do A and β represent?
A is the forward amplifier gain, while β is the feedback factor. They help us analyze how feedback influences the system's overall gain.
What happens when we apply negative feedback?
Negative feedback effectively lowers the gain from 'A' to 'A/(1 + Aβ)'. Think of it as a speed limit: curbing the output for stability!
Practical Applications of Feedback Systems
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Let's discuss practical applications. Where might we see these feedback systems used?
In amplifiers, for sure!
Absolutely! Feedback systems are integral in amplifiers to control gain and reduce distortion.
Can feedback systems be used in other devices?
Yes! They're used in temperature controls, audio systems, and many other electronic devices. Remember: 'Feedback builds bridges!'
How do we analyze feedback systems practically?
By measuring the input and output, analyzing the transfer functions, and modifying the feedback path as needed, we can optimize performance.
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The section discusses the principles of feedback systems, detailing different configurations, types of feedback (positive and negative), and the derived transfer characteristics. It emphasizes the practical applications of these concepts in amplifiers and linear circuits.
Detailed
Detailed Summary
In this section, we explore the Feedback System as a crucial aspect of analog electronic circuits. Starting with the foundational theory, feedback systems are introduced as methods of sampling output signals and routing them back to affect the input signal, primarily in amplifiers. The section delineates four basic configurations of feedback systems: negative feedback and positive feedback. The distinctions between these two types are emphasized, demonstrating how they either negate or amplify the original input signal based on feedback polarity. Furthermore, the section covers the derivation of the transfer characteristic of the feedback system, providing essential expressions for analyzing circuit behavior. By understanding these concepts, students can grasp how feedback influences the performance and stability of electronic circuits.
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Overview of Feedback Systems
Chapter 1 of 6
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Chapter Content
So, students welcome back to our online certification course on Analog Electronic Circuits. Myself Pradip Mandal from E and EC department of IIT, Kharagpur. Today’s topic of discussion it is Feedback System. So, we shall start with basics and then gradually, we will be moving to practical circuit.
Detailed Explanation
In this introductory part of the lecture, the speaker welcomes the students to the course. The focus is on Feedback Systems, suggesting that both foundational concepts and practical applications will be covered in the session. This sets the stage for learning about various feedback mechanisms that are fundamental in electronics, especially in analog circuits.
Examples & Analogies
Think of learning to ride a bicycle. Initially, you might need to start with the basics of balance. Just like the lecture begins with foundational concepts of feedback systems before diving into more complex applications, learning to ride a bike involves mastering balance before you can ride smoothly.
Plan for the Session
Chapter 2 of 6
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Chapter Content
So, the based on our plan overall plan, we are in modules in fact, whatever the concepts we will be talking it is primarily on analog modules and today we are starting this week-10. In fact, it is module-9 and as I said that we are going to talk about feedback system.
Detailed Explanation
Here, the speaker outlines the lesson structure, indicating that the focus will be primarily on analog modules related to Feedback Systems. This structured approach helps students understand the progression of topics and gives them an expectation of what they will learn in this session and the upcoming modules.
Examples & Analogies
Imagine planning a journey where you outline the stops along the way. Just as having a map helps you follow a route effectively to reach your destination, this session plan helps students navigate through complex topics in feedback systems systematically.
Basic Concepts of Feedback Systems
Chapter 3 of 6
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Chapter Content
To start with the basic concept of feedback system so, far we are talking about amplifiers. In fact, different amplifier configurations and those amplifiers are essentially linear circuit. So, we can say that at the input, we are applying input signal either it may be in the form of voltage or current. On the other hand at the output, we are observing the corresponding amplified version of the input signal and this A represents the amplification factor.
Detailed Explanation
This section introduces the basic model of feedback systems centered around amplifiers. It explains how amplifiers work in a circuit where an input signal (voltage or current) is amplified. The amplification factor 'A' signifies how much the input signal is increased at the output, setting a foundation for understanding how feedback is implemented in these systems.
Examples & Analogies
Consider a microphone connected to an amplifier that makes your voice louder when you speak into it. The input is your voice (a sound signal), and the output is the amplified sound. This basic model is akin to how feedback systems work, adjusting the output for optimal performance.
Understanding Feedback in Amplifiers
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Chapter Content
Whenever you are talking about the feedback system, what we are trying to do, we are essentially sampling this signal and part of it we are taking back and we are given to the input. In fact, while we are taking this feedback signal from the output, we also have to retain the corresponding input port primary port for feeding the signal.
Detailed Explanation
In feedback systems, a portion of the output signal is fed back into the input signal. This process helps adjust the system's behavior, maintaining control over the output. The feedback loop consists of sampling the output and combining it with the original input, which can influence the overall performance of the amplifier.
Examples & Analogies
Think of it like a coach giving you advice during a game. By observing your performance (the output), they provide feedback to adjust your strategy (input) to improve overall play. Similarly, feedback systems adjust behaviors to enhance outputs.
Components of a Feedback System
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So, if you see the model we use, it is given here from this point to the primary output, we do have the forward amplifier take which is taking the signal from left to right and then part of this signal...we are combining a part of this signal and the feedback signal to generate the input signal for the amplifier.
Detailed Explanation
This section dives into the components of a feedback system: the forward amplifier, feedback path, and input signal mixer. The forward amplifier processes the primary input signal, and the feedback path allows part of the output to influence the input signal. This interaction between components is crucial for the feedback system's effectiveness.
Examples & Analogies
Consider a water heating system that uses feedback to maintain the desired temperature. The heater acts like the forward amplifier, while the thermostat acts as the feedback mechanism. As the water heats up (output), some of that information tells the heater when to adjust its activity (input), ensuring stable temperatures.
Types of Feedback Systems
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Chapter Content
So, based on the feedback signal coming back, we may call either it is ‒ve or +ve and if you see here, when you call it is ‒ve feedback system it is essentially for exchange at a point in the feedback system or circuit.
Detailed Explanation
Feedback systems can be classified into two types: negative (‒ve) feedback and positive (+ve) feedback. The key difference lies in how the feedback signal interacts with the original input signal. Negative feedback reduces the effect of the input change, while positive feedback amplifies it.
Examples & Analogies
Think of a thermostat again. If the temperature rises above the set point, the thermostat turns off the heater (negative feedback). Conversely, if the heater encourages more warmth, and the thermostat keeps adjusting to promote even higher temperatures, that would be like positive feedback.
Key Concepts
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Feedback Systems: Systems that route output signals back to inputs.
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Negative Feedback: Opposes any changes in a system, promoting stability.
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Positive Feedback: Enhances changes, typically leading to instability.
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Transfer Characteristic: Relationship analysis between input and output.
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Applications of Feedback: Utilized in amplifiers, temperature controls, etc.
Examples & Applications
A thermostat using negative feedback to maintain a set temperature.
The screech of a microphone that is too close to a speaker represents positive feedback.
Memory Aids
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Rhymes
Feedback flows, like rivers run; Negative calms, while positive's fun.
Stories
Imagine a thermostat regulating home temperatures. When it gets too warm, it cools down. That’s negative feedback. But picture a microphone too close to its speaker; it screams with feedback, that's the positive kind!
Memory Tools
To remember types of feedback: 'N for Negative, P for Positive.'
Acronyms
Use the acronym F.E.E.D to remember
Feedback Enhances
Evens
and Defines (system behavior).
Flash Cards
Glossary
- Feedback System
A system that takes a portion of its output and feeds it back as input, influencing the input signal.
- Negative Feedback
Feedback that opposes the original input signal, stabilizing the output.
- Positive Feedback
Feedback that enhances or amplifies the original input signal.
- Transfer Characteristic
A mathematical representation of the relationship between input and output signals in a feedback system.
- Amplifier
An electronic device that increases the amplitude of a signal.
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