GATE 2014 EC (EC2) – Question 57
A minimum-phase system has the shown asymptotic Bode magnitude plot. Connected in unity negative feedback, find its closed-loop steady-state error for a unit-ramp input.
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Correct answer: 0.49 to 0.51
Explanation
The low-frequency magnitude has slope−20dB/decade, indicating one integrator. Atω=1rad/s the magnitude asymptote is6.02dB, or2, so Kv=lim(s→0)sG(s)=2. For the stable unity-feedback system, unit-ramp error is1/Kv=**0.5**. The constant region and later pole do not change Kv.