13.3.3 Understanding feedback and stability

• Open-loop gain is the gain of an operational amplifier without feedback.

  True
• Feedback in operational amplifiers always enhances stability.

  False
• Positive feedback reduces noise in operational amplifiers.

  False
• Match the benefit of feedback with its description:

  Gain Stability ↔️ Maintains consistent gain

  Improved Linearity ↔️ Reduces distortion

  Enhanced Stability ↔️ Prevents oscillations
• Open-loop gain is the gain of an amplifier without any feedback
• What are the key benefits of feedback in operational amplifiers?

  Controlled gain, enhanced stability
• What does positive feedback do to the input signal in an operational amplifier?

  Boosts the input signal
• What is the definition of open-loop gain in an operational amplifier?

  Gain without feedback
• Where is open-loop gain useful in circuits?

  Comparator circuits
• What determines the gain value in closed-loop gain?

  Feedback resistors
• What effect does feedback have on the stability of the closed-loop gain?

  Increases stability
• Negative feedback is essential for achieving stability in operational amplifiers.

  True
• Negative feedback reduces gain but makes the amplifier more stable and less sensitive to external changes
• Negative feedback is ideal for amplifiers requiring consistent output
• Match the feedback type with its effect on stability:

  Positive Feedback ↔️ Causes oscillations or latching

  Negative Feedback ↔️ Enhances stability and reduces noise
• Open-loop gain is highly stable and unaffected by temperature changes.

  False
• What type of gain ensures greater stability in operational amplifiers?

  Closed-loop gain
• Feedback in closed-loop systems ensures a stable, predictable, and controlled gain
• Match the feedback type with its effect on stability:

  Positive Feedback ↔️ Causes oscillations and instability

  Negative Feedback ↔️ Enhances stability and reduces noise
• What is feedback in operational amplifiers?

  Output signal fed back
• Closed-loop gain in operational amplifiers is influenced by the ratio of feedback resistors
• List the techniques for ensuring stability with feedback in operational amplifiers.

  1️⃣ Reduce open-loop gain

  2️⃣ Increase phase margin

  3️⃣ Use frequency compensation
• What effect does positive feedback have on gain in operational amplifiers?

  Increases dramatically
• Which type of feedback is suitable for audio amplifiers requiring consistent output?

  Negative feedback
• What is the typical value range of open-loop gain in operational amplifiers?

  100,000 to 1,000,000
• Negative feedback in operational amplifiers reduces gain and enhances stability.


  True
• Positive feedback can potentially cause oscillations or saturation
• The typical gain value of an open-loop operational amplifier ranges from 100,000 to 1,000,000, which is extremely high
• Open-loop gain needs external feedback to stabilize and regulate its performance
• Unlike open-loop gain, closed-loop gain ensures stable and accurate amplification
• The use of feedback in closed-loop gain improves the amplifier's linearity, reducing distortion
• How does feedback help increase the gain of an operational amplifier?

  By feeding back output
• Positive feedback can cause oscillations or saturation
• The open-loop gain of an operational amplifier without feedback ranges from 100,000 to over 1 million
• Open-loop gain has a very high gain value, while closed-loop gain is controlled by resistors
• Closed-loop gain ensures stable and accurate amplification, unlike open-loop gain.


  True
• What is the primary role of feedback in achieving stability in operational amplifiers?

  Controls gain
• What technique ensures the phase shift around the loop is significantly less than -180 degrees at the unity-gain frequency?

  Phase Margin
• Positive feedback in operational amplifiers can lead to instability
• What is stability in operational amplifiers?

  Resistance to oscillations