GATE EC 2016 Set 2 — Question 56
Go beyond PYQs with Success TrackerAI-powered personalised practice and doubt support. Unlimited practice on eligible plans; AI usage limits apply.NAT+2 / -0MediumGain & Phase MarginStability AnalysisControl Systems
Control Systems → Stability Analysis → Gain & Phase Margin
Last updated
Question
In the feedback system shown below .
The positive value of for which the gain margin of the loop is exactly 0 dB and the phase margin of the loop is exactly zero degree is ________

Correct answer
59.5 to 60.5
Solution
The open-loop transfer function is .
The characteristic equation is .
Expanding the terms: .
For the gain margin to be 0 dB and phase margin to be 0 degrees, the system must be marginally stable.
Using the Routh-Hurwitz criterion:
.
The characteristic equation is .
Expanding the terms: .
For the gain margin to be 0 dB and phase margin to be 0 degrees, the system must be marginally stable.
Using the Routh-Hurwitz criterion:
- : 1, 11
- : 6,
- :
- :
.
Continue learning with Success Tracker
A step still unclear? Work through it with support
Use Success Tracker to ask about the reasoning, then try another GATE EC question to check your understanding.
AI-powered practice· Unlimited practice on eligible plans
- PYQs with solutions
- Attempt available previous-year questions, then compare your reasoning with the worked solution. Coverage varies by stream.
- Practice that adapts
- Choose a topic, work on weaker areas and bookmark questions to revisit. Your attempts feed your progress tracking.
- AI doubt support
- Ask follow-up questions about a step or concept while practising, instead of stopping at the final answer.
Unlimited practice is available on eligible plans. Free practice and AI usage have limits; check the current plan allowances before choosing.
This page stays readable without an account. AI responses can be wrong; check them against the solution and source material.
More questions on Stability Analysis
2026 Set 1 Q11Consider the differential equation , with…2026 Set 1 Q19A control system is shown in the Figure. Which option represents the correct transfer function of…2026 Set 1 Q40For the control system shown in the Figure, the transfer function of a plant,…2026 Set 1 Q41The state and output equations for a control system are:…2026 Set 1 Q59Consider the unity negative feedback control system shown in the Figure. The value of gain …