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Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Understanding Voltage Gain
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Today we're diving into how we calculate the voltage gain of an ideal feedback system. Can anyone tell me what voltage gain represents?
It's the ratio of output voltage to input voltage, right?
Exactly! In our case, we have a forward amplifier gain, A, of 200. When we include feedback, we use the formula Aβ² = A / (1 + Ξ²A). What do you think happens to the gain?
I think it will decrease because of the feedback. What's the result in this case?
Right again! The gain drops to 10. That's an important concept because it shows how feedback affects system performance.
So the gain is reduced, but why is that a good thing?
Great question! Reducing gain can improve stability and reduce distortion, which is crucial in practical applications.
To summarize, the introduction of feedback in our ideal network reduces voltage gain, which can enhance performance. I want you to memorize that feedback can lower gain while improving stability.
Calculating Input Resistance
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Now let's transition to input resistance. Who can explain what input resistance is?
It's the resistance seen by the input source when connected to the amplifier.
Correct! In our ideal feedback network, we calculated the input resistance as R_in = R_in_v Γ (1 + Ξ²A). Given our parameters, how does this affect R_in?
It increases significantly. In fact, here it goes from 1 kβ¦ to 20 kβ¦!
Exactly! This increase in resistance is beneficial as it minimizes the loading effect on the previous stage. Can anyone define the term 'loading effect'?
It's the impact an input load has on a circuit's performance or output.
Well said! A higher input resistance means less loading effect, ensuring better overall circuit behavior.
To wrap up, remember that feedback enhances input resistance, boosting performance by reducing loading. Let's keep that in mind!
Exploring Output Resistance
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Next, we should look at output resistance. What happens to output resistance when feedback is introduced?
I believe it decreases, right?
Yes! In this case, our output resistance dropped to 200 β¦ due to the shunt configuration of feedback. Why is this significant?
It helps deliver more power to the load, improving the amplifier's efficiency!
Exactly! A low output resistance allows for better current delivery without significant voltage drop. Can anyone summarize the importance?
Lower output resistance improves power transfer and efficiency!
Well done! Low output resistance in feedback networks is essential for effective power delivery in electronic circuits.
Calculating Output Voltage
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Now, let's find the output voltage based on the input voltage and the gain. If we have an input signal of 100 mV, what's the output voltage given our calculated gain?
Would it be 10 times 100 mV, so 1 V?
That's correct! The output voltage is directly influenced by the input signal and the gain. Knowing this relationship is crucial for designing amplifiers.
Is this relationship the same in non-ideal cases too?
Good catch! While the relationship remains, non-ideal conditions will alter the gain, which affects the output voltage.
Let's conclude on the key takeaway: Understanding output voltage calculations helps predict circuit behavior, essential in design.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
In this section, we analyze an ideal feedback network's characteristics, exploring its voltage gain, input and output resistances, and output voltage given defined parameters. The introduction of an ideal feedback network highlights key concepts of desensitization factors and their implications on circuit behavior.
Detailed
Ideal Feedback Network Analysis
In an ideal feedback network, we explore how the circuit behaves with infinite input resistance and zero output resistance. Given a forward amplifier gain (A) of 200 and a feedback factor (Ξ²) of 0.095, we examine the effects on the feedback system's gain, input resistance, output resistance, and output voltage.
Key Calculations
- Voltage Gain (Aβ²): The voltage gain is calculated considering the desensitization factor which impacts the overall gain of the feedback system. With A = 200, Aβ² results in 10 after calculation.
- Input Resistance (R_in): The input resistance of the feedback system is significantly increased, calculated as R_in = R_in_v Γ (1 + Ξ²A), which results in a total resistance of 20 kβ¦.
- Output Resistance (R_out): The output resistance is affected by shunting, leading to a calculated output resistance of 200 β¦.
- Output Voltage (V_out): Given an input voltage of 100 mV, the output voltage corresponds to 10 Γ 100 mV, producing a total of 1 V.
This section also contrasts ideal scenarios with non-ideal scenarios, paving the way toward understanding real-world applications of feedback systems and the inherent trade-offs involved.
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Audio Book
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Introduction to Feedback System Calculations
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So here we do have numerical example and what is our objective here? It is that we need to find the voltage gain of the feedback system, input resistance, output resistance of the feedback system and the output voltage for an input voltage or the signal voltage of 100 mV.
Detailed Explanation
In this section, we are tasked to perform calculations related to a feedback system. Specifically, we need to determine the voltage gain, input resistance, output resistance, and the output voltage for a given input signal of 100 mV. These parameters are crucial for understanding how the feedback network affects overall system performance.
Examples & Analogies
Imagine you're trying to amplify the sound from a small speaker (the forward amplifier) to fill a large room. The feedback system helps optimize how well the sound spreadsβjust like how we calculate gain and resistance in electronic circuits.
Parameters of the Feedback System
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And the parameters of the feedback systems are given here input resistance and output resistance of the forward amplifier and the gain of the forward amplifier it is 200 feedback network, the feedback factor it is 0.095.
Detailed Explanation
We are provided with key parameters of the feedback system: the input resistance, output resistance of the forward amplifier, and the forward amplifier gain, which is 200. The feedback factor, denoted by Ξ², is 0.095. These values are essential for calculating how the feedback will influence the overall behavior of the system.
Examples & Analogies
Think of these parameters like ingredients in a cooking recipe. Just as the right proportions affect the dish's flavor, these electrical parameters affect the circuit's performance.
Ideal Feedback Network Characteristics
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let me consider this relatively simpler case, case-1 where we consider ideal feedback network having the input resistance it is infinite and its output resistance on the other hand it is 0 as we are generating voltage.
Detailed Explanation
In an ideal feedback network, we assume that the input resistance is infinite and the output resistance is zero. This means that the network does not load the preceding stage (infinite input resistance), and it can deliver voltage without any loss (zero output resistance). This simplification allows for easier calculations and provides an understanding of theoretical performance limits.
Examples & Analogies
Imagine a perfect speaker system that doesn't distort sound no matter how loud you make it (infinite input resistance) and can deliver sound without losing any quality (zero output resistance). This is the ideal scenario we strive for in electronic circuits.
Voltage Gain of the Feedback System
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So the gain of the feedback system it is 10. Now, to find the value of the input resistance R_in_f.
Detailed Explanation
The voltage gain of the feedback system has been calculated to be 10. This means when an input signal of 100 mV is applied, the output will be 1000 mV (or 1 V). The gain reduction from the forward amplifier is an important aspect of feedback networks, as it shows how feedback affects performance.
Examples & Analogies
If you're amplifying your voice 10 times using a microphone, every 1 mV of your voice becomes 10 mV in sound output, just like how feedback affects voltage in a circuit.
Calculating Input Resistance
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So note that just by this feedback network the input resistance it is getting increased by a factor of 20 which means that if the main amplifier input resistance it was 1 k, the feedback system input resistance it is becoming 20 k.
Detailed Explanation
The feedback network increases the input resistance by a factor of 20. For instance, if the original input resistance of the amplifier was 1 kβ¦, after applying the feedback, it becomes 20 kβ¦. This increase is beneficial in applications where higher input impedance is crucial to prevent loading of the preceding stage.
Examples & Analogies
Think of this increase as a more sensitive microphone. A more sensitive microphone (higher resistance) can pick up softer sounds without being affected by background noise. The same concept applies when we enhance the input resistance in circuits.
Calculating Output Resistance
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So the output resistance it will be = = 200 β¦.
Detailed Explanation
For the output resistance of the feedback system, the feedback connection reduces it to 200 β¦. This reduction means the output can drive loads more effectively. Lower output resistance helps in delivering power to the load without voltage drop.
Examples & Analogies
This is similar to using a strong battery to power several devices. As the battery has low internal resistance, it can deliver power to all devices efficiently without losing power along the way.
Final Output Voltage Calculation
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So the output voltage v_o is 10 Γ 100 mV = 1 V.
Detailed Explanation
The final output voltage has been found to be 1 V, which is a straightforward calculation based on the previously determined voltage gain. Understanding how output voltage correlates to input voltage through the gain is fundamental in feedback systems.
Examples & Analogies
It's like turning on the volume of a radio. If you set it to multiply the sound by 10 times, every gentle whisper turns into an audible voice, illustrating the amplification principle at work.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
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Gain Reduction: The effect of feedback reduces the voltage gain in a feedback system.
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Increased Input Resistance: Feedback increases the input resistance, minimizing loading effects on the previous stage.
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Decreased Output Resistance: An ideal feedback network decreases the output resistance to improve power transfer efficiency.
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Desensitization Factor: Reflects how input and output resistance values change with feedback integration.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
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If the input voltage is 100 mV and the gain is 10, the output voltage is 10 Γ 100 mV = 1 V.
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In an ideal feedback network, the input resistance increased from 1 k⦠to 20 k⦠due to the feedback factor.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
π΅ Rhymes Time
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In feedback networks, gain goes down, input resistance wears the crown.
π Fascinating Stories
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Imagine a crowded theater, where feedback represents whispers that spread across the audience, reducing the volume of the original performance, much like how feedback reduces gain.
π§ Other Memory Gems
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GIRD: Gain Increases Resistance Decreases (Feedback characteristic summary).
π― Super Acronyms
FINE
- Feedback Increases input
- Normalizes output (Characteristics of feedback).
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Voltage Gain
Definition:
The ratio of output voltage to input voltage in an amplifier.
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Term: Input Resistance
Definition:
The resistance encountered by the input signal in an amplifier circuit.
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Term: Output Resistance
Definition:
The resistance presented by the output of an amplifier circuit.
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Term: Feedback Factor (Ξ²)
Definition:
The fraction of the output voltage fed back to the input.
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Term: Desensitization Factor
Definition:
A factor that indicates how the input resistance and output resistance change with feedback.