Closed Loop Negative Feedback Gain Calculator

Formula Used:

\[ A_f = \frac{A_o}{1 + (\beta \times A_o)} \]

Gain with Feedback (A_f):

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1. What is Closed Loop Negative Feedback Gain?

Closed Loop Negative Feedback Gain (A_f) represents the gain of an operational amplifier circuit when negative feedback is applied. It provides a more stable and predictable amplification compared to the open-loop gain, making it essential for practical amplifier designs.

2. How Does the Calculator Work?

The calculator uses the closed-loop gain formula:

\[ A_f = \frac{A_o}{1 + (\beta \times A_o)} \]

Where:

\( A_f \) — Gain with Feedback (Closed Loop Gain)
\( A_o \) — Open Loop Gain of the OP-AMP
\( \beta \) — Feedback Factor

Explanation: The formula demonstrates how negative feedback reduces the overall gain of an amplifier system while improving stability, bandwidth, and linearity.

3. Importance of Closed Loop Gain Calculation

Details: Calculating closed loop gain is crucial for designing stable amplifier circuits, controlling frequency response, and ensuring predictable performance in various electronic applications including audio amplifiers, instrumentation systems, and control systems.

4. Using the Calculator

Tips: Enter the open loop gain (A_o) in V/V and the feedback factor (β) as a dimensionless quantity. Both values must be positive numbers for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why use negative feedback in amplifier circuits?
A: Negative feedback improves stability, increases bandwidth, reduces distortion, and makes the gain less dependent on the open-loop characteristics of the amplifier.

Q2: What is the relationship between open-loop and closed-loop gain?
A: Closed-loop gain is always less than open-loop gain. As feedback factor increases, closed-loop gain decreases but becomes more stable and predictable.

Q3: What are typical values for open-loop gain?
A: Typical operational amplifiers have open-loop gains ranging from 10,000 to 1,000,000 V/V (80-120 dB).

Q4: How does feedback factor affect circuit performance?
A: Higher feedback factors provide better stability and linearity but result in lower overall gain. The feedback factor determines the trade-off between gain and performance characteristics.

Q5: When is this formula not applicable?
A: This formula assumes ideal op-amp characteristics and may need modification for very high frequencies, non-ideal op-amps, or when considering phase margins and stability criteria.