Differentiate negative and positive feedbacks. Write the name of all four negative feedback configurations.

Q.) Differentiate negative and positive feedbacks. Write the name of all four negative feedback configurations.

 Subject: electronic devices and circuits

Negative Feedback:

Negative feedback is a control mechanism that opposes a change in a system. It acts to maintain a stable equilibrium by counteracting any deviation from the set point. In negative feedback, the output of a system is used to reduce the input. This results in a decrease in the system's output, bringing it back closer to the set point.

Positive Feedback:

Positive feedback is a control mechanism that amplifies a change in a system. It acts to accelerate the deviation from the set point, leading to instability. In positive feedback, the output of a system is used to increase the input. This results in an increase in the system's output, driving it further away from the set point.

Four Negative Feedback Configurations:

  1. Negative Feedback with Proportional Control:
  • This is the simplest form of negative feedback.
  • The output is directly proportional to the error signal.
  • The error signal is the difference between the set point and the actual output.
  • The proportional gain determines the strength of the feedback.

  • The transfer function for proportional control is:

    $$G(s) = K_p$$

    where:

    • $$K_p$$ is the proportional gain.
  1. Negative Feedback with Integral Control:
  • This type of feedback eliminates steady-state errors.
  • The output is proportional to the integral of the error signal.
  • The integral gain determines the strength of the feedback.

  • The transfer function for integral control is:

    $$G(s) = K_i / s$$

    where:

    • $$K_i$$ is the integral gain.
  1. Negative Feedback with Derivative Control:
  • This type of feedback provides anticipatory control.
  • The output is proportional to the derivative of the error signal.
  • The derivative gain determines the strength of the feedback.

  • The transfer function for derivative control is:

    $$G(s) = K_d s$$

    where:

    • $$K_d$$ is the derivative gain.
  1. Negative Feedback with PID Control:
  • PID control is a combination of proportional, integral, and derivative control.
  • It is the most widely used feedback control algorithm.

  • The transfer function for PID control is:

    $$G(s) = K_p + K_i / s + K_d s$$

    where:

    • $$K_p$$ is the proportional gain.
    • $$K_i$$ is the integral gain.
    • $$K_d$$ is the derivative gain.