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The asymptotic Bode magnitude plot of a minimum phase transfer function is shown in the figure
This transfer function has
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- Three poles and one zero
- Two poles and one zero
- Two poles and two zeros
- One pole and two zeros
Correct Option: C
Transfer function of given plot is of the form
| T(s) = | ||
| s2 |
so, it will have two poles and two zeroes.
First – 40 dB/decade slope indicates 2 pole in system.
Next – 20 dB/decade slope indicates 1 zero is added.
Next – dB/decade slope indicates 1 more zero is added.
Alternately
At ω = 0.1, slope changes from – 40 dB/decade to – 20 dB/decade, then, zero at ω = 0.1
At, ω > 0.1, slope changes from – 20dB/decade to 0 dB/decade, then one more zero at ω > 0.1
Since, for ω < 0.1, slope is – 40 dB/decade there is alveag two poles. Hence (c) is the correct option.
