Loading the lesson
Loading the lesson
Search AllRounder.ai
Search the courses, subjects, tracks, games and features, or jump straight to a page.
Search the courses, subjects, tracks, games and features, or jump straight to a page.
Learn it your way
A short class with Sarah and her students. The other ways are under More.
Sign up free to listen. Transcripts are free to read.
Welcome, class! Today, we will discuss how feedback networks affect the frequency response of amplifiers. Can anyone tell me what a feedback network is?
Isn’t 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, there’s 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.
Let’s 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. Let’s visualize this with a Bode plot next.
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.
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.
A routing mechanism for part of an output signal back into the input to control system behavior.
The position in the s-plane affecting the stability and frequency response of the system.
The product of forward gain and feedback factor that indicates overall system stability.
Feedback's a loop, where signals renew, Gaining control while the bandwidth grew.
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.
Remember the word 'GAP' for feedback: Gain reduction, Amplifier stability, Pole shifting.
FBA: Feedback, Bandwidth, Amplifier - the trio to mastering feedback systems.
Term
What is the definition of a feedback network?
Click to flip
Term
Why are poles significant in control systems?
Click to flip
A method used to route part of an output signal back to the input of a system to control its behavior.
A value of 's' in a transfer function at which the function becomes infinite, affecting system behavior and stability.
The ability of an amplifier to increase the strength of a signal, usually measured in decibels (dB).
A transformation technique used to analyze linear time-invariant systems using complex frequency variable 's'.
The product of the forward gain and feedback factor in a feedback control system.
This section discusses the effects of feedback networks on the frequency response of amplifiers in analog electronic circuits, focusing on the influence of pole locations.
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.
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 gain—defined as + (where is the forward amplifier gain and represents the feedback network's impact)—is 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.