Question

Consider the feedback system shown in the figure. The Nyquist plot of G(s) is also shown. Which one of the following conclusions is correct?

(A) G(s) is an all-pass filter

(B) G(s) is a strictly proper transfer function

(C) G(s) is a stable and minimum-phase transfer function

(D) The closed-loop system is unstable for sufficiently large and positive k 

Answer 1

Correct option (D) The closed-loop system is unstable for sufficiently large and positive k

Explanation:

For larger values of K, it will encircle the critical point (-1+j₀), which makes closed-loop system unstable.