- #1

- 145

- 0

## Homework Statement

I'm doing a question that requires a Bode plot (magnitude and phase).

## The Attempt at a Solution

I got a transfer function of

[tex]H(\omega)=\frac{1+\frac{j*\omega}{3}}{1-0.1667(\omega)^{2}+0.4167j*\omega}[/tex]

So there is a simple zero at 3 rad/s; complex pole at 2.45 rad/s; and no DC gain.

I am able to plot the magnitude plot correctly, however my phase isn't exactly right.

For phase I have essentially two contributions from the zero and the pole:

From zero: 0.3<omega<30 rad/s with a slope of 45 degrees/decade

From pole: 0.245<omega<24.5 rad/s with a slope of -90 degrees/decade

So combining the two, I get (w==omega, i'm too lazy to write it out):

0<w<0.245: 0 degrees,

0.245<w<0.3: slope of -90 degrees/decade

0.3<w<24.5: slope of -45 degrees/decade

24.5<w<30: slope of 45 degrees/decade

w>30: slope of 0

However the solution my prof provided says:

0<w<0.245: 0 degrees,

0.245<w<0.3: slope of -90 degrees/decade

0.3<w<24.5: slope of -45 degrees/decade

w>24.5: slope of 0, flattens out at -90 degrees.

Am I wrong? If so, why?