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If the open-loop gain decreases due to the frequency or the effects of the system aging, providing that βG is still very large, then the overall system gain ______ (Where G is Open loop voltage gain and β is the feedback fraction)1. does not change very much2. increases very much3. decreases very much4. fluctuates accordingly inputs |
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Answer» Correct Answer - Option 1 : does not change very much Concept: Negative feedback system: The transfer function of the negative feedback closed-loop control system is given by TF = G/ (1 + βG) Where, G = open-loop gain β = feedback factor or gain Explanation: Given that, The open-loop gain is decreased due to the frequency or the effects of the system aging. But the βG is still large Then, The overall gain will be TF = (G↓) / (1 + βG↓) As βG is still very large we can neglect 1 (1 << βG) ⇒ TF or Overall gain ≈ G / βG ≈ 1\β Hence, if we neglect 1 in the denominator then there is no change in the gain even though if there is a change in open-loop gain, but if we consider 1 also then there will be a slight change(decreases) in the overall gain not much. |
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