Effects of Negative Voltage Feedback on an Amplifier

• Reduction in Gain: The overall closed-loop gain is lower than the open-loop gain (A).
• Gain Stability: Closed-loop gain becomes less sensitive to variations in A (caused by temperature changes, transistor aging, etc.).
• Improved Linearity: Distortion is reduced since feedback forces the amplifier to correct its own errors.
• Reduced Noise: Noise generated within the amplifier is partly cancelled.
• Increased Bandwidth: The reduction in gain results in a wider frequency response, thereby increasing bandwidth.
• Improved Input and Output Impedance:
  • Input impedance increases, which is desirable for voltage amplifiers.
  • Output impedance decreases, allowing better load-driving capability.

  Advantages of Using Negative Feedback

  • Stabilized Gain: Gain becomes less dependent on transistor parameters.
  • Reduced Nonlinear Distortion: Provides better signal fidelity.
  • Reduced Noise: Results in a cleaner output signal.
  • Increased Bandwidth: Enhances high-frequency performance.
  • Improved Impedance Matching: Facilitates cascading of amplifier stages.
  • Overall Improved Performance: Enhances predictability, reliability, and efficiency of the amplifier.