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Welcome, everyone! Today, we will explore non-ideal feedback networks. Can anyone tell me what they think a non-ideal feedback network means?
I think it refers to feedback systems that don't have the ideal conditions, like infinite input resistance or zero output resistance.
Exactly! In non-ideal feedback networks, both the input and output resistances are finite. This significantly affects circuit performance. Let's dive into how these parameters are calculated.
Can you remind us what those parameters are?
Sure! We typically assess the voltage gain, input resistance, and output resistance. Remember the acronym 'VIO' for Voltage, Input, and Output resistances. Now, let's look at a specific numerical example.
Consider a feedback system with a forward amplifier gain of 200 and a feedback factor of 0.095. Let's calculate the voltage gain of the feedback system.
How do we start?
First, we find the modified gain A', which combines the input resistance and feedback factor. It is given by the formula: A′ = A * Load factor. Who can tell me that load factor based on our parameters?
It would be A multiplied by the loading voltage, right?
Correct! Now let's calculate this step-by-step.
When we have non-ideal feedback, how can we express the input resistance with feedback?
Isn't it R_in * (1 + βA)?
Exactly! This shows how feedback enhances the input resistance. Can anyone explain how output resistance behaves?
I think the output resistance decreases due to shunting effects.
Right! It effectively divides the total resistance. Understanding these relationships is crucial.
Let’s wrap up by calculating the output voltage with the given input of 100 mV. Using the gain we've calculated, how would you find the output voltage?
By multiplying the gain with the input voltage, right?
Exactly! This will give us V_out. What’s our outcome if we continue with this?
In this case, it would yield an output voltage of 1V since the gain is 10.
Correct! Great job applying everything we've learned today.
The enhancement or reduction of voltage in the output compared to the input caused by the feedback mechanism.
Characteristics of a circuit affecting how it interacts with external components.
Key role in determining how feedback influences circuit behavior.
Feedback's a loop, round and round, where added signal is what we've found.
Imagine a feedback loop as a well. The water that flows back into the well strengthens the source, much like how feedback helps stabilize circuits.
VIO: Remember Voltage gain, Input resistance, and Output resistance.
FIR: Feedback, Input, Output resistances governs the circuit efficiency.
Term
Desensitization Factor
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Term
Feedback Factor
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A parameter that quantifies the portion of output fed back to input in a feedback system.
A measure of how much the overall gain of the feedback system is reduced compared to the open-loop gain.
The resistance faced by the input signal of a circuit or feedback system.
The resistance seen by the output load in a feedback system.
The ratio of output voltage to input voltage in a circuit.
This section addresses the characteristics and calculations involved in analyzing a non-ideal feedback network in analog electronic circuits.
The section delves into a specific case of non-ideal feedback networks, highlighting the differences in voltage gain, input and output resistance, and output voltage as compared to ideal feedback systems. Various calculations and derivations are presented to illustrate how these parameters are affected in a scenario involving finite input and output resistances.
In this section from Prof. Pradip Mandal's lecture on Analog Electronic Circuits, we explore the intricacies of a non-ideal feedback network. We begin by establishing the significance of understanding the impact of finite input and output resistance, which deviates from ideal conditions. The use of a numerical example facilitates a deeper understanding of the voltage gain, input resistance, output resistance, and resulting output voltage for a given input signal. The calculations illustrate how the feedback factor modifies these parameters, providing foundational insights into feedback systems in electronic circuits. Notably, the section emphasizes the desensitization factor and introduces techniques for calculating load-affected gains and resistances, thereby reinforcing the relationship between feedback mechanisms and circuit performance.