Poly Notes Hub‘s today’s topic is Feedback Amplifier and Types of Feedback Amplifier. Here we discuss about the feedback circuit and describe their types. Important topic for Diploma Engineering Students.
Author Name: Arun Paul.
What is Feedback Circuit?
The process of injecting a fraction of the output energy of some device back to the input is known as Feedback and the circuit is called a Feedback Circuit.
What is Feedback Amplifier?
An electronic amplifier that employs feedback to regulate its gain, bandwidth, linearity, and other characteristics is known as a feedback amplifier. Therefore, not all feedback circuits are feedback amplifiers, even though feedback amplifiers always involve feedback circuits. In particular, feedback amplifiers employ feedback to adjust or enhance their performance characteristics.
Types of Feedback Amplifier
There are two basic types of Feedback in Amplifier –
- Positive Feedback
- Negative Feedback
Below we discuss about these feedback –
Positive Feedback
When the feedback energy (voltage and current) is in phase with the input signal and thus aids it, it is called positive feedback. This is illustrated in Fig. The amplifier and feedback network introduce a phase shift of 180°. The result is a 360° phase shift around the loop, causing the feedback voltage Vf to be in phase with the input signal Vin.
Advantages of Positive Feedback
- It increases the gain of the amplifier.
Disadvantages of Positive Feedback
- It increases the distortion.
- This circuit is not stable as well.
Applications of Positive Feedback
- It is used in Oscillator circuits. An oscillator is a device that converts DC power into AC power of any desired frequency.
Negative Feedback
When the feedback energy (voltage and current) is out of phase with the input signal and thus opposes it, it is called negative feedback. This is illustrated in Fig. As you can see, the amplifier introduces a phase shift of 180° into the circuit while the feedback network is so designed that it introduces no phase shift (i.e., 0° phase shift). The result is that feedback voltage Vf is 180°out of phase with the input signal Vin.
Advantages of Negative Feedback
- It reduces the distortion.
- It decreases the noise.
- Increases the input impedance.
- It is stable.
- Decreases the output impedance.
Disadvantages of Negative Feedback
- It reduces the gain of the amplifier.
Applications of Negative Feedback
- Used in Amplifiers.
Conclusion | Diploma Engineering Notes | Poly Notes Hub
In this note, we are discuss about the Feedback Circuit and Types of Feedback Circuit. Our Poly Notes Hub provides syllabus-wise notes for polytechnic or diploma engineering students of streams like Electrical Engineering, Electronics Engineering, Electrical and electronics Engineering, Electronics & Instrumentation Engineering, and Computer Science & Technology. Our website is updating day by day so keep in touch with us for new and syllabus-wise notes and topic which helps you all to do any task regarding diploma engineering.