Professional Courses
Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.
Categories
Interactive Games
Fun, engaging games to boost memory, math fluency, typing speed, and English skillsβperfect for learners of all ages.
Typing
Memory
Math
English Adventures
Knowledge
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Introduction to Feedback and Amplifiers
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Welcome, class! Today, we will discuss how feedback networks affect the frequency response of amplifiers. Can anyone tell me what a feedback network is?
Isnβt it related to sending part of the output back to the input?
Exactly! Feedback is used to control the gain and stability of an amplifier. Now, does anyone recall the types of feedback?
Yes, thereβs positive and negative feedback.
Correct! In our analysis, we will focus on *negative feedback*. What is the expected outcome of negative feedback on amplifier gain?
It typically reduces gain but improves stability.
Well done! Always remember, negative feedback may reduce gain but enhances linearity and bandwidth. Now let's dive into the concept of poles in the frequency response.
Understanding Poles in Feedback Systems
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Letβs consider the concept of poles. In terms of a transfer function, how do we represent poles?
Poles are the values of 's' for which the denominator of a transfer function becomes zero.
Exactly! And the placement of these poles can greatly affect system stability. When feedback is applied, how does it shift these poles?
It shifts the poles left in the s-plane, which can indicate improved stability?
Yes! A leftward shift shows a more stable system. Letβs visualize this with a Bode plot next.
Feedback System Analysis in Laplace Domain
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
In our analysis, we will use the Laplace transform. Can anyone remind me of what the Laplace transform helps us do?
It helps us analyze systems in the frequency domain, right?
Correct! In the Laplace domain, our transfer function is affected by the loop gain, which is a product of the forward gain and feedback factor. What does this loop gain help us determine?
It helps us assess the overall stability and response of the feedback system.
Excellent point! As we proceed, keep in mind how these relationships can lead to design decisions in actual circuit applications.
Frequency Response Shifts
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Now, what happens to the frequency response as we apply feedback to an amplifier with one pole?
The gain at low frequencies decreases, but the bandwidth increases.
Right! We see a trade-off between gain and bandwidth due to pole shifting. Can anyone summarize this relationship?
As the effective pole location shifts, it increases the system's frequency response near the new pole.
Well said! Remember, the feedback effect also generates design implications that we will explore further with two-pole systems.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
The section provides an overview of how feedback affects the frequency response of amplifiers, examining cases with one or two poles. It emphasizes the changes in pole locations due to feedback and the implications for amplifier behavior in both time and frequency domains.
Detailed
Effect of Feedback on Frequency Response
This section delves into the intricate relationship between feedback networks and the frequency response of amplifiers in analog electronic circuits. Specifically, it pertains to how the presence of feedback alters the gain and pole locations within the system. The feedback system's outcome can be observed in various linear circuits, although the discussion centers on amplifiers.
Feedback can dramatically influence amplifier characteristics such as gain, bandwidth, and stability. Here, we explore scenarios where amplifiers have different pole counts (one, two, etc.) and how these configurations interact with the feedback network. We also assess pole location shifts due to feedback and discuss implications for system stability under negative feedback conditions.
The section outlines the Laplace domain analysis of feedback systems, emphasizing transfer functions and their frequency dependencies. The role of the loop gainβdefined as + (where is the forward amplifier gain and represents the feedback network's impact)βis critical to understanding how feedback enhances or diminishes amplifier performance.
Lastly, several cases are explored, including ideal conditions with constant feedback. We examine how changes in the pole locations relate to stability and performance, offering insight into the design and analysis of feedback systems in practical applications.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Introduction to Feedback and Frequency Response
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Dear students and participants, welcome back to our NPTEL online certification course on Analog Electronic Circuits myself Pradip Mandal from E and EC department of IIT Kharagpur. Todayβs topic of discussion it is; it is continuation of feedback circuit and what we will see that the Effect of Feedback network on Frequency Response of the forward amplifier.
Detailed Explanation
In this segment, the speaker welcomes students and introduces the topic of feedback circuits in analog electronic circuits. They explain that they will focus on how feedback networks influence the frequency response of forward amplifiers. This means looking at how feedback can change the amplifier's ability to process different frequencies effectively.
Examples & Analogies
Think of a feedback network like a team coach giving advice to an athlete during a race. If the coach provides helpful feedback, the athlete can adjust their speed and strategy to perform better against their competitors, especially under varying conditions.
Frequency Response and Gain Focus
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
In general, we can say that it is valid for even other linear circuit, but our specific focus it will be on amplifier. And also the when you say frequency response, it is primarily our focus it will be on gain of the amplifier, but that is also applicable for impedance.
Detailed Explanation
Here, the speaker emphasizes that although the discussion revolves around amplifiers, the principles apply more broadly to other linear circuits. The key focus of the discussion will be on frequency response, which relates to how the gain of an amplifier varies with different frequencies. This is crucial for understanding the overall performance of the amplifier not just in terms of gain but also in impedance, which affects how circuits interact with signals.
Examples & Analogies
Imagine a musician tuning their instrument. Just like the musician adjusts the pitch (frequency) to ensure the notes sound right, engineers adjust the frequency response of an amplifier to make sure it amplifies the desired signals without distortion or loss.
Poles in Feedback Systems
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
The concepts we will be covering today it is primarily how the locations of the poles are getting changed, in the feedback system and that is due to the location of the amplifiers poles and also the poles of the feedback network.
Detailed Explanation
In this section, the focus shifts to the technical aspects of feedback systems. The speaker discusses the importance of 'poles', which are specific frequenciesβthe higher the pole, the more stable the amplifier is at processing signals. This means that the placement of these poles in the circuits is crucial, as they can significantly impact how feedback affects the overall frequency response of the system.
Examples & Analogies
Consider the poles of a seesaw. When you adjust where the people are sitting (like adjusting the pole locations), it determines how balanced and stable the seesaw is when moving. Similarly, changing the location of poles in a circuit affects how stable and effective it is at handling different signal frequencies.
Analyzing Feedback Effects
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Now, let us come to the first case before we go into the first case again we like to recapitulate what we have discussed. In fact, we have discussed this kind of situation where this is the forward amplifier, this is the feedback network.
Detailed Explanation
The speaker is now shifting to practical examples of how to analyze specific cases within feedback systems. They begin to recall prior discussions and set the stage for examining how a standard forward amplifier is structured alongside a feedback network. This will pave the way for understanding how these components interact and influence one another, particularly in terms of system performance and stability.
Examples & Analogies
Think of a manufacturing line where a worker (the forward amplifier) receives feedback from a quality control team (the feedback network). By evaluating how well they perform, the worker can adjust their technique to improve quality and efficiency, similar to how amplifiers adjust their output based on varying feedback.
Understanding Stability in Feedback Systems
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, we will be discussing about amplifier which is linear circuit and in presence of βve feedback the linear system remains linear.
Detailed Explanation
This part highlights an important principle about linear amplifiers using negative feedback. Negative feedback helps the overall system remain linear, thus keeping the amplification effective and stable across different conditions without introducing significant distortion.
Examples & Analogies
Consider a thermostat controlling room temperature. When the temperature exceeds a set point, it signals the heater to reduce output. Similarly, negative feedback in amplifiers adjusts the signal input/output to maintain a consistent performance without over-amplifying or creating distortion.
Analyzing Gain and Loop Gain Interactions
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
The effectiveness of this feedback network or the loop gain to change this transfer function of the feedback system is also, it also depends on the location of the poles and of course, we do have the desensitization factor.
Detailed Explanation
The speaker elaborates on how the feedback network (loop gain), which is the measure of how much the output influences the input, is fundamentally linked to the pole locations within the system. The concept of 'desensitization factor' introduces the idea that as feedback changes, the system's sensitivity to inputs also changes, affecting the output. This feedback influences the transfer functionβ how the input signal translates to the output signal in the circuit.
Examples & Analogies
Think of feedback like a coach encouraging a sports team. The coachβs influence (loop gain) can change how the team reacts (transfer function) based on their performance metrics (poles), with desensitization acting like adjusting the coachβs intensity based on how the team is performing in each game.
Impact of Poles on Feedback System
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Suppose this A is having one pole then what is its influence on the location of the pole of the feedback system?
Detailed Explanation
Here, the discussion dives deeper into how the presence of a single pole impacts the overall feedback system. The location of this pole will determine key characteristics of the system like stability, frequency response, and gain changes. Understanding how to manipulate and analyze these poles into feedback systems is essential for designing effective circuits.
Examples & Analogies
It's like adjusting the gear on a bicycle. A single gear (pole) affects your speed and stability; shifting this gear changes how smoothly you can ride, just as moving pole locations influences how effectively the feedback system performs.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Feedback Network: A routing mechanism for part of an output signal back into the input to control system behavior.
-
Pole Location: The position in the s-plane affecting the stability and frequency response of the system.
-
Loop Gain: The product of forward gain and feedback factor that indicates overall system stability.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
A feedback amplifier circuit with a pole at s = -1 changes the frequency response, indicating higher stability.
-
Introducing a feedback factor of Ξ² = 0.5 can shift pole locations and demonstrate an increase in system bandwidth.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
π΅ Rhymes Time
-
Feedback's a loop, where signals renew, Gaining control while the bandwidth grew.
π Fascinating Stories
-
Imagine a feedback loop in a bakery, where the baker adjusts the oven's heat based on how well the bread rises, illustrating how feedback influences optimal outcomes.
π§ Other Memory Gems
-
Remember the word 'GAP' for feedback: Gain reduction, Amplifier stability, Pole shifting.
π― Super Acronyms
FBA
- Feedback
- Bandwidth
- Amplifier - the trio to mastering feedback systems.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Feedback Network
Definition:
A method used to route part of an output signal back to the input of a system to control its behavior.
-
Term: Pole
Definition:
A value of 's' in a transfer function at which the function becomes infinite, affecting system behavior and stability.
-
Term: Gain
Definition:
The ability of an amplifier to increase the strength of a signal, usually measured in decibels (dB).
-
Term: Laplace Domain
Definition:
A transformation technique used to analyze linear time-invariant systems using complex frequency variable 's'.
-
Term: Loop Gain
Definition:
The product of the forward gain and feedback factor in a feedback control system.