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 back, class! Today, we're going to discuss feedback in amplifier circuits. Can anyone tell me why feedback is necessary in amplifiers?
To improve stability?
Exactly! Feedback helps to stabilize gain and reduce distortion. What are the basic configurations we've learned?
There are voltage shunt, current shunt, voltage series, and current series configurations.
Great! These configurations determine how we sample signals in the feedback loop. For instance, in voltage shunt, we sample the output voltage while the input is a current. This setup leads to specific characteristics in the gain and resistance.
What happens to the gain if we apply negative feedback?
Good question! Negative feedback tends to reduce the gain by a factor known as the desensitization factor. Can anyone summarize how we analyze these configurations?
We need to look at how the input and output resistances change in relation to the gain.
Exactly! Understanding these relationships is key to applying feedback effectively.
Now let's dive deeper into BJT feedback configurations. Who can explain the shunt-shunt feedback configuration?
In shunt-shunt feedback, both the input and output are sampled as voltages, right?
Correct! In this case, both the input resistance and output resistance decrease by the desensitization factor. Why do we use this configuration?
To stabilize the input resistance and decrease it simultaneously!
That's right! What about the series-series configuration, can anyone elaborate?
In series-series, both input and output resistances increase.
Exactly! This is useful when we want to increase the overall input impedance of the system. Remember, the ultimate goal of feedback here is to stabilize critical parameters like voltage gain and trans-conductance.
And we must consider the consequences on current gain as well!
Very well put! Let’s summarize: When configuring feedback, always analyze how it affects these parameters.
Let's switch gears and consider operational amplifiers. In which configurations do we typically implement feedback?
Inverting and non-inverting amplifiers!
That's correct! In an inverting amplifier, what happens to the gain when negative feedback is applied?
The gain becomes negative relative to the input signal!
Exactly! And what does that tell us about the stability of the circuit?
It helps to stabilize the gain and reduce distortion in the output.
Absolutely! Always remember that feedback affects each stage's functionality. Can anyone mention the effect of feedback in integrators and differentiators?
Integrators build up voltage over time, while differentiators respond to changes.
Exactly! So choosing the right configuration will dictate both the performance and response of the amplifier.
The use of feedback in amplifiers to stabilize gain and performance.
A feedback mechanism that reduces output and stabilizes the amplifier's gain.
A feedback configuration that samples voltage from both input and output.
A configuration that samples signals based on current to affect overall gain.
Feedback's the track, that keeps circuits intact.
Imagine a choir where each singer's voice is adjusted by the conductor—this is like feedback balancing sound in amplifiers.
R.A.T. – Remember Amplifiers Type: Recall how Resistor configurations Adjusts the stability in the amplifier feedback.
S.C.A.R. – Stabilize, Control, Adjust, Reinforce: The roles of feedback in amplifiers.
Term
What is feedback?
Click to flip
Term
Define negative feedback.
Click to flip
A process in which a portion of the output signal is returned to the input to enhance circuit performance.
Bipolar Junction Transistor; a type of transistor that uses both electron and hole charge carriers.
Feedback that samples voltage based on the output signal, usually affecting input and output resistances.
Feedback configuration where the signal is sampled based on current, affecting the output gain.
A factor that reduces the gain of the amplifier due to negative feedback.
This section explores practical applications of feedback in amplifier circuits, discussing different configurations and their effects on amplifier performance.
The section delves into how feedback is applied in various amplifier circuits, specifically through transistor-level configurations like BJT and operational amplifiers. It details the impact of feedback on amplifier characteristics and stability.
In this section, we investigate the implementation of feedback systems in amplifier circuits, specifically focusing on three BJT configurations: shunt-shunt feedback, series-series feedback, and shunt-series feedback. These configurations are examined in relation to their effects on the amplifier gain and the input and output resistances. Furthermore, we extend the discussion to op-amp circuits, covering inverting amplifiers and non-inverting configurations, along with the introduction of two feedback loops. The significance of the feedback factor in stabilizing circuit parameters is emphasized, and the consequences of feedback deployment are systematically analyzed.