# Questions & Answers of Bode Plots

A Bode magnitude plot for the transfer function G(s) of a plant is shown in the figure. Which one of the following transfer functions best describes the plant?

The Bode magnitude plot of the transfer function $G\left(S\right)=\frac{K\left(1+0.5s\right)\left(1+as\right)}{s\left(1+\frac{s}{8}\right)\left(1+bs\right)\left(1+\frac{s}{36}\right)}$ is shown below: Note that -6 dB/octave = -20 dB/decade. The value of $\frac{a}{bk}$ is_____________.

For the transfer function

$G\left(S\right)=\frac{5\left(s+4\right)}{s\left(s+0.25\right)\left({s}^{2}+4s+25\right)}$

The values of the constant gain term and the highest corner frequency of the Bode plot respectively are

The gain $\left(20log\left|G\left(s\right)\right|\right)$ is 32 dB and –8 dB at 1 rad/s and 10 rad/s respectively. The phase is negative for all ω. Then G(s) is