At the critical frequency, a loop phase shift of 360 degrees can lead to which condition?

At the critical frequency, a loop phase shift of 360 degrees can lead to which condition?

• A. Overshoot
• B. Oscillations
• C. Steady-state Error
• D. Damping

Answer: (B)

In a feedback loop, a phase shift of 360 degrees means the feedback signal is in phase with the input. If, at that frequency, the loop gain is unity (the critical frequency), the feedback reinforces the input rather than opposing it. That sets up the Barkhausen condition for sustained oscillations: the signal keeps circulating without dying out or growing, producing a steady oscillatory output. Overshoot, steady-state error, and damping relate to other aspects of how a system responds, but the key idea here is that in-phase feedback at unity gain enables continuous oscillations.

In a feedback loop, a phase shift of 360 degrees means the feedback signal is in phase with the input. If, at that frequency, the loop gain is unity (the critical frequency), the feedback reinforces the input rather than opposing it. That sets up the Barkhausen condition for sustained oscillations: the signal keeps circulating without dying out or growing, producing a steady oscillatory output. Overshoot, steady-state error, and damping relate to other aspects of how a system responds, but the key idea here is that in-phase feedback at unity gain enables continuous oscillations.