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GATE 2014 EC (EC4) – Question 30

Control Systems · Bode and Root-Locus Plots · 1 mark · Multiple choice

What high-frequency Bode magnitude slope does a fourth-order all-pole system exhibit?

  1. −80 dB/decade
  2. −40 dB/decade
  3. +40 dB/decade
  4. +80 dB/decade

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Correct answer: (A) −80 dB/decade

Explanation

At frequencies well beyond all four poles, each pole contributes−20dB/decade to the magnitude asymptote. With no finite zeros to offset them, the total slope is4×(−20)=**−80dB/decade,A**.