Output Resistance With Feedback Voltage Amplifier Calculator

Formula Used:

\[ R_{vof} = \frac{R_o}{1 + A\beta} \]

Output Resistance with Feedback (R_vof):

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1. What is Output Resistance with Feedback Voltage Amplifier?

The output resistance with feedback in a voltage amplifier is the effective resistance seen at the output terminals when negative feedback is applied. It is a crucial parameter that determines how the amplifier's output voltage changes with varying load conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ R_{vof} = \frac{R_o}{1 + A\beta} \]

Where:

\( R_{vof} \) — Output resistance with feedback (Ohm)
\( R_o \) — Output resistance without feedback (Ohm)
\( A\beta \) — Loop gain of the amplifier (dimensionless)

Explanation: Negative feedback reduces the output resistance of a voltage amplifier by a factor of (1 + Aβ), making the amplifier's output more stable and less dependent on load variations.

3. Importance of Output Resistance Calculation

Details: Calculating output resistance with feedback is essential for designing stable amplifier circuits, ensuring proper impedance matching, and predicting performance under different load conditions.

4. Using the Calculator

Tips: Enter the output resistance without feedback (R₀) in Ohms and the loop gain (Aβ). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why does negative feedback reduce output resistance?
A: Negative feedback creates a corrective mechanism that opposes changes in output voltage, effectively making the output appear as a lower impedance source.

Q2: What is typical range for loop gain (Aβ)?
A: Loop gain values typically range from 10 to 1000 or more, depending on the amplifier design and feedback network.

Q3: How does output resistance affect amplifier performance?
A: Lower output resistance provides better voltage regulation, improved load driving capability, and reduced signal loss when connected to subsequent stages.

Q4: Can this formula be used for all types of amplifiers?
A: This formula specifically applies to voltage amplifiers with negative feedback. Other amplifier types (current, transconductance, transresistance) have different feedback effects.

Q5: What are practical applications of this calculation?
A: This calculation is used in audio amplifiers, operational amplifier circuits, RF amplifiers, and any application where stable output voltage under varying loads is required.