### Bode Plots (Bode Magnitude and Phase Plots) - Topic wise Questions in Control Systems ( from 1987)

2003
1. The approximate Bode magnitude plot of a minimum phase system is shown in figure. The transfer function of the system is

2004

2. Consider the Bode magnitude plot shown in figure. The transfer function H(s) is

3. A system has poles at 0.01 Hz, 1 Hz and 80 Hz; zeros at 5 Hz, 100 Hz and 200 Hz. The approximate phase of the system response at 20 Hz is
a) - 90o
b) 0o
c) 90o
d) - 180o

2006

4. Consider two transfer functions G1(s) = 1 / (s2 + as + b) and G2(s) = s / (s2 + as + b). The 3 dB bandwidths of their frequency responses are, respectively

Solution :

2007

5. The asymptotic Bode plot of a transfer function is as shown in figure. The transfer function G(s) corresponding to this Bode plot is

2008

6. The magnitude of frequency response of an under damped second order system is 5 at 0 rad/sec and peaks to 10/√3 at 5√2 rad/sec. The transfer function of the system is

2010

7. A system with transfer function Y(s)/X(s) = s/(s + p) has an output y(t) = cos(2t – π/3) for the input signal x(t) = p cos(2t – π/2). Then, the system parameter 'p' is
a) √3
b) 2/√3
c) 1
d) √3/2

8. For the asymptotic bode magnitude plot shown below, the system transfer function can be

2013

9. The Bode plot of a transfer function G(s) is shown in the figure below.
The gain (20log|G(s)|) is 32 dB and – 8 dB at 1 rad/sec and 10 rad/sec respectively. The phase is negative for all ω. Then G(s) is
a) 39.8/s
b) 39.8/s2
c) 32/s
d) 32/s2

2014

10. The Bode asymptotic magnitude plot of a minimum phase system is shown in the figure.
If the system is connected in a unity negative feedback configuration, the steady state error of the closed loop system, to a unit ramp input is _____________

11. In a Bode magnitude plot, which one of the following slopes would be exhibited at high frequencies by a 4th order all pole system?

2015

12. Consider the Bode plot shown in figure.

Assume that all the poles and zeros are real valued. The value of fH – fL (in Hertz) is ____________________