91.3.1 - Signal Connections and Ideal Model
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Understanding Feedback Systems
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Today we'll explore feedback systems in analog circuits. Let's start with what a feedback system is. Can anyone define it?
Is it something that helps control the output back to the input?
Exactly! Feedback systems use the output to regulate the input. Now, let's talk about the two types of signals we often deal with: voltage and current. Can anyone tell me how they differ?
I think voltage is the potential difference, while current is the flow of charge.
Correct! Voltage is measured in volts, and current in amperes. Understanding how we sample and mix these signals is key to the next part of our discussion.
Voltage Sampling and Mixing
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In a voltage feedback system, both input and output signals are voltages. We use a parallel connection for sampling and a series connection for mixing. Who can summarize why we assume these connections?
To avoid loading effects, right? If we assume infinite or zero resistance, it prevents signal loss.
Exactly! Good point. We also name these configurations based on their routing. What do we call a configuration with shunt sampling and series mixing?
It’s called shunt-series feedback, I think!
Yes! Well done! Let's remember this naming convention, as it helps us categorize different feedback systems quickly.
Current Feedback Systems
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Now, let's shift gears and talk about current feedback systems. When both signals are current, what type of connections do we use?
For current feedback, don't we use series for the sampler and parallel for the mixer?
That's correct! The connections change based on the type of signal. What's important is to maintain ideal conditions. Why do we need these ideal conditions, Student_2?
To avoid loading effects, like we mentioned before!
Exactly again! The practice of defining the resistance values to ideal conditions simplifies our calculations and designs. Anyone recall what happens to the gain in this situation?
I think the loop gain retains its sign, and the overall system becomes sensitive to feedback.
Correct! The negative feedback gain is crucial to ensure system stability.
Challenge of Real-world Applications
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While we've talked about ideal conditions, real-world feedback systems often don't meet these assumptions. Can anyone think of what this could mean for designs?
Maybe the calculations wouldn't be accurate, leading to poor performance?
Exactly! If the resistances are finite, we must consider those effects, which complicates calculations. This affects both the gain and how we analyze the input and output resistances of the system.
So really, ideal models only get us so far, right?
Right! That's why understanding both the ideal and non-ideal scenarios is essential for effective designs.
Introduction & Overview
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Quick Overview
Standard
The section delves into various configurations of feedback systems, detailing how voltages and currents are sampled and mixed. It highlights the importance of ideal conditions to avoid loading effects, and explains naming conventions for different types of feedback networks.
Detailed
Detailed Summary
This section examines the configurations of feedback systems in analog electronic circuits, detailing how signals (voltage and current) are connected through different methods—namely sampling and mixing. It presents two configurations of feedback systems, explaining how input signals can be sampled in series or parallel, which dictates the connection types used in the feedback loops.
Key Configurations:
- Voltage Feedback Systems: In this first configuration, both input and output signals are voltages. The section explains how these signals are sampled and combined using parallel and series connections, and how the ideal conditions of infinite and zero resistances are assumed to eliminate loading effects.
- Current Feedback Systems: This configuration changes input and output signals to currents, leading to a flip in their connections. The teacher clarifies the significance of signal polarity and the behavior of current in terms of its signs, reinforcing that these configurations also have to adhere to ideal conditions to ensure proper functioning.
Ideal Model Considerations:
The section emphasizes how the resistive values for input and output in ideal models are defined as infinite and zero, respectively, in order to create scenarios where loading effects are negligible. It also indicates how configurations are named based on their sampling and mixing types, summarizing common terminologies used in textbooks.
By outlining the principles governing feedback configurations for both voltage and current, this section equips students with fundamental knowledge on how to model feedback systems effectively, emphasizing the importance of understanding both theoretical assumptions and practical implications.
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Basic Model of Signal Connections
Chapter 1 of 5
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Chapter Content
In this case as I said that the input signal and output signal are say voltages. So, here we consider it is voltage here also it is voltage, so the signal here it is voltage and this is also voltage.
Detailed Explanation
This chunk introduces the basic concept that both the input and output signals in the given model are voltages. Understanding that both signals are in the form of voltage is crucial because it sets the foundation for how these signals will be processed and manipulated in the feedback system.
Examples & Analogies
Imagine you are looking at two streams of water (the input and output signals). If both streams are of the same type (for example, both are water), then you can manipulate them together in the same way, just like we do with voltages in an electronic circuit.
Sampling and Mixing Connections
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So, we do have parallel port. On the other hand if you see signal here they are voltages, so our intention is to use these two voltages to generate this S or v . These two signal sources they are connecting in series.
Detailed Explanation
This chunk explains the concept of sampling and mixing in voltage signals. The text mentions that the output signal is sampled via a parallel connection while ensuring the two voltage sources that contribute to generating a signal S are connected in series. This highlights two crucial types of connections in the model: parallel sampling for the output and series mixing for generating the desired voltage.
Examples & Analogies
Think of a DJ creating a new song by sampling sounds. The DJ 'samples' (or records) some music from one source (parallel connection) and then combines it with sounds from another source (series connection) to create a unique track. In our circuit, we sample and mix voltages in a similar creative way.
Ideal Model Considerations
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Assuming there is no loading effect... we have considered this ideal situation namely the resistance here it is ∞. So, I am keeping this is open so, R it is ∞. On the other hand output resistance here R , so that is equal to 0.
Detailed Explanation
In this chunk, the text introduces the concept of ideal models in electronic circuits. It explains that for the analysis, we assume that the resistance at certain points is infinite and zero at others. This simplifies the model by eliminating loading effects, which can distort signals. These assumptions help in analyzing how the system behaves under ideal conditions.
Examples & Analogies
Consider a traffic flow scenario where we want to test how traffic lights work without cars actually being there (ideal situation). By assuming no cars (loading effect), we can see how the traffic system would work in the best possible scenario before applying it to real conditions where cars do exist.
Feedback System Structure
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We said that the A is remaining A, we do not have to consider A′. On the other hand, R of this feedback network which is R′ which is we are assuming it is 0.
Detailed Explanation
This portion discusses the relationship between the ideal model's parameters and how they remain unchanged under ideal conditions. It states that the overall gain 'A' of the system doesn't change despite the feedback introduced, as long as input resistance R' is assumed to be zero. These points reinforce the concept of maintaining stable and consistent feedback in circuit designs.
Examples & Analogies
Think of a company that maintains its core values (A) regardless of shifts in the market (feedback). Just as the company's fundamental ethos does not change when external factors come into play, the circuit's gain remains constant under ideal conditions, simplifying our analysis.
Configuration Naming
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So, we may say that shunt sampling and series mixing. To compress it typically we use this word and this word. So, alternatively this configuration it can be named as shunt series feedback system or you may say that here the signal it was voltage, so we can say that voltage series feedback.
Detailed Explanation
This chunk addresses how configurations in electrical circuits are named based on the connections used. The system can be referred to as 'shunt series feedback' due to how the signals are sampled and mixed together. Understanding the naming conventions helps in recognizing and discussing these configurations in different contexts.
Examples & Analogies
Imagine naming different types of sandwiches based on their ingredients and how they are made. A 'Layered Veggie Sandwich' may refer to one with various veggies layered neatly, while a 'Mixed Potato Salad Sandwich' highlights the mixing of potatoes. Similarly, the names in circuit configurations describe the connections used and how signals flow, making it easier to communicate about them.
Key Concepts
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Signal Connections: The importance of understanding how signals interact in feedback systems.
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Ideal vs Non-ideal Models: The differences between theoretical models and real-world applications.
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Naming Conventions: The classification of configurations based on signaling methods.
Examples & Applications
A voltage feedback system where voltage is sampled in parallel and mixed in series to maintain integrity of signal.
A current feedback system where current is sampled in series, then mixed in parallel to ensure proper feedback processes.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
To mix and sample, don't you see, Voltage and current dance with glee!
Stories
Imagine a voltage signal trying to cross a river; it jumps into parallel boats (shunt connection) and sails across to meet a current signal in a series race on the other side.
Memory Tools
Shunting Signal means Sampling Silk: Remember shunt and series sampling types!
Acronyms
VSM - Voltage Sampling Mixer
helps remember the combination in feedback.
Flash Cards
Glossary
- Feedback System
A system that uses signals from the output to control the input.
- Shunt Connection
A type of connection where signals are parallelly connected.
- Series Connection
A type of connection where signals are connected to allow current to flow sequentially.
- Loading Effect
The phenomenon where the presence of a circuit causes a significant reduction in the signal due to impedance mismatches.
- Ideal Model
A theoretical analysis where certain assumptions are made to simplify behavior, e.g., infinite resistance.
Reference links
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