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Introduction to Feedback Systems
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Today we're going to discuss feedback systems in analog electronic circuits. Can anyone share what feedback means in this context?
Is it when the output of a system is fed back into the input?
Exactly! That's a great definition. Feedback is crucial as it helps stabilize and adjust the system's performance. There are primarily two types of feedback: positive and negative. Can anyone tell me how they differ?
Negative feedback reduces the output, like controlling a thermostat?
Yes! And positive feedback increases the output, often pushing the system towards instability or oscillation. Remember, negative feedback is generally used for stabilization.
So negative feedback is more beneficial usually?
Correct! It usually enhances stability and performance.
To summarize, feedback is essential for controlling the behavior of electronic circuits. We'll explore calculations related to voltages and resistances next.
Calculating Gain and Resistence
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Letβs start calculating the voltage gain for an ideal feedback system. Who can tell me the formula for voltage gain in feedback systems?
Is it A' = A / (1 + Ξ²A)?
Exactly right! For our case with A = 200 and Ξ² = 0.095, letβs do the math together. What do we get for A'?
If we substitute, it should be A' = 200 / (1 + 200 * 0.095). It simplifies to 10!
That's correct! You can see how feedback significantly reduces the gain. What about input resistance?
Isnβt it affected by the desensitization factor? The input resistance should increase?
Yes, right! For a forward amplifier with an input resistance of 1 kβ¦, it becomes 20 kΞ©. So, what do we conclude about our ideal system's performance?
The feedback allows us to have higher input resistance and lower output resistance!
Great summary! Remember, this ideal case sets a benchmark for understanding how feedback can enhance circuit performance.
Effects of Non-Ideal Feedback
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Now, letβs discuss non-ideal feedback systems. How does introducing finite resistance change our previous results?
I think it would make the input resistance lower?
Thatβs right! With finite input resistance, our calculations adjust. Can anyone explain how we'd calculate the new values?
We have to consider both loading effects and the new resistances, right?
Yes! The loading factor is essential. If the input resistance is 200 β¦, how does that affect the gain?
I think A' would be less than before because it would see less input voltage.
Exactly! Thus, our new gain appears to be much lower. Effective changes often require careful accounting of all resistances involved. What was the resultant output voltage from a 100 mV input?
I think it becomes about 655.73 mV.
Well done! Understanding these changes is vital in real-world applications, as non-ideal feedback is common.
Summary and Application
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What have we learned about feedback systems? Can someone summarize key points?
We learned the difference between ideal and non-ideal feedback systems and how it affects gain and resistance.
Exactly! What applications do you think this knowledge helps with?
Designing stable amplifiers and understanding how to optimize their performance!
Great! Feedback systems are crucial in a myriad of electronic designs. With real applications requiring us to handle both conditions, professionals need to be adept at these calculations.
This was enlightening! It clarifies why we need to design circuits carefully.
Yes! And always keep practicing those calculations. Letβs keep feedback considerations in mind for our future circuit designs!
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
The section provides in-depth analysis and calculations related to the feedback system in analog electronic circuits. Key findings involve understanding the effects of different configurations on voltage gain, input resistance, and output resistance, illustrating how system parameters change under ideal and non-ideal conditions.
Detailed
Detailed Summary
In this section, we explore the impact of feedback systems in analog electronic circuits, emphasizing the calculations involved in determining voltage gain, input resistance, and output resistance. We first demonstrate these calculations under ideal conditions, where the feedback network is assumed to have infinite input resistance and zero output resistance, significantly enhancing the system's performance.
The first case illustrates an ideal feedback system with a forward amplifier gain of 200 and a feedback factor of 0.095, leading to a feedback system gain of 10 (calculated as A' = A / (1 + Ξ²A)). This example shows how the input resistance increases by a factor of 20, while the output resistance decreases, resulting in a 1V output voltage from a 100mV input signal.
Transitioning to a non-ideal scenario, we analyze the impact of finite resistances in the input and output stages. This analysis highlights how the parameters diminish the overall voltage gain and alter resistance values, leading to more complex calculations. For instance, using a loading factor calculation, we derive a modified gain and adjusted resistances accordingly, demonstrating that the output voltage drops to approximately 655.73mV under these conditions.
The insights gained from this section are foundational for understanding the application of feedback in electronic systems and underscore the importance of analyzing both ideal and non-ideal behaviors to predict system performance accurately.
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Overview of Feedback Systems
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So to summarize all these 4 sub-lectures, what we have discussed in this topic of feedback system. So far we have talked about basic concepts of the feedback system, there we have introduced how we define the feedback system and then we have talked about 2 basic types of feedback mechanism or feedback system namely, +ve feedback type and βve feedback types feedback system.
Detailed Explanation
In the introduction of feedback systems, we defined what a feedback system is and why it is essential in electronic circuits. We highlighted that there are two primary types of feedback: positive feedback, which amplifies the input signal, and negative feedback, which stabilizes the output by reducing gain. This foundational understanding serves as a basis for more complex discussions.
Examples & Analogies
Think of a feedback system like adjusting the volume on a sound system. When the volume is too high and causes distortion (negative feedback), you turn it down for clarity. Conversely, if the sound is too low and you'd like to boost it (positive feedback), you turn it up. Feedback systems in electronics operate on similar principles.
Feedback Transfer Characteristics
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And subsequent discussion it is mostly related to βve feedback system. So then, we have talked about transfer characteristic of feedback system namely, feedback system transfer characteristic A = . So also, we have talked about loop gain = β Ξ²A then, desensitivity factor, D = (1 + Ξ²A).
Detailed Explanation
In discussing negative feedback, we emphasized the transfer characteristics of such systems. We defined the relationship where the overall gain (A) is determined by the loop gain (which is the product of feedback factor and amplifier gain, represented as -Ξ²A) and introduced the desensitivity factor (D) that quantifies how adverse effects on gain can be mitigated (D = 1 + Ξ²A). Understanding these terms is crucial for evaluating the performance and stability of feedback systems.
Examples & Analogies
Imagine you're trying to balance a seesaw. If one side is heavier (think of this as applying a 'gain'), you'll need to add weight to the other side to level it out. The desensitivity factor can be thought of as a way to gauge how much weight you need to add to balance the seesaw, just like adjusting the feedback can stabilize the output in electronic systems.
Feedback Configurations
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Then we have talked about 4 basic configurations which normally it is common in electronic circuit and we have discussed about their characteristic. So these are the enlisted 4 basic configurations we have discussed about how the gain it is getting changed.
Detailed Explanation
We discussed four common configurations of feedback systems used in electronic circuits: voltage series, voltage shunt, current series, and current shunt feedback. Each configuration has unique characteristics that affect how gain is modified, input and output resistances are altered, and the overall performance of the circuit is optimized. These configurations provide a framework for engineers when designing feedback systems to achieve desired performance.
Examples & Analogies
Consider a water faucet with a varying flow of water. When you adjust the handle (like changing the feedback configuration), you either increase or decrease the water flow (gain). Similar to how different faucet settings can control water output, various feedback configurations allow engineers to control electrical signals.
Practical Exercises and Application
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And also we have talked about how the input resistance and output resistance of the system it is getting changed by the desensitization factor. And then we have discussed about 2 numerical examples associated with 2 feedback configure different types of configuration starting with ideal situation and then also we have moved to non-ideal situation.
Detailed Explanation
In our discussion on practical applications of feedback systems, we analyzed how the input and output resistances are affected by feedback factors, illustrating the desensitization impact. We worked through two numerical examples that explored ideal and non-ideal feedback scenarios. By examining these calculations, students learned how theory translates into practical design challenges, enhancing their problem-solving skills.
Examples & Analogies
Think about tuning a radio. In an ideal situation (like you can hear clearly), the signal is strong with minimal interference. But in a non-ideal situation (where thereβs static), you need to adjust the dial (feedback) to minimize disturbances. The numerical examples provided are analogous to these tuning exercises, helping students see the practical application of theory in real-world scenarios.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
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Feedback Systems: Mechanisms that adjust output based on feedback from the output.
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Voltage Gain: The ratio of the output voltage to the input voltage.
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Input Resistance: Resistance faced by the input signal.
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Output Resistance: Resistance presented to the load connected at the output.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
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In an ideal feedback system with a forward gain of 200 and a feedback factor of 0.095, the output gain is calculated as A' = 10.
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In a non-ideal case where the input resistance is 200 ohms and output resistance is 1k ohms, the modified voltage output becomes 655.73mV from an initial 100mV signal.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
π΅ Rhymes Time
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Feedback helps circuits grow, make signals strong, keep distortions low.
π Fascinating Stories
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Imagine a teacher giving feedback to a student. The student improves each test, just like a feedback system enhances performance.
π§ Other Memory Gems
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FIVE: F - Feedback, I - Input, V - Voltage, E - Energy - always remember the components of feedback systems.
π― Super Acronyms
GAIN - G - Gain, A - Amplifier, I - Input, N - Network.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
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Term: Feedback Factor (Ξ²)
Definition:
The proportion of the output that is fed back into the input of the system.
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Term: Desensitization Factor
Definition:
The factor by which feedback amplifies the input resistance and alters the output resistance.
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Term: Output Resistance (R_out)
Definition:
The resistance seen by the load connected to the output of a circuit.