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solution solution

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Code: omg = 0.01:0.01:10000; num = [20,0];den = [1,20,10000]; sys = tf(num,den); figure(1),bode(omg,sys);grid on Magnitude (dB) Phase (deg) 0 -10 -20 -30 -40 90 45 0 -45 -90 10 1 Asymptote: Bode Diagram 10 2 Frequency (rad/sec) j20ω H( jω) = ( jω+ 10 − j99.5)( jω+ 10 + j99.5) ω j j20ω = = 500 2 2 ⎡ ω ω ⎤ 10000 ⎢1− + j ⎛ ω ⎞ ω 10000 500 ⎥ 1− ⎜ ⎟ + j ⎣ ⎦ ⎝100 ⎠ 500 From the expression, we see the frequency response have: zero at jω = 0 , a pair of complex conjugate poles at jω =− 10 + j99.5 and jω = −10 − j99.5 . (1). Magnitude asymptote 10 3

The dB-scale magnitude asymptote from zero j 500 ω is a straight line with a slope of 20dB and go through (500,0), as shown (dashed line). The dB-scale magnitude asymptote from pole ⎛ ω ⎞ ω 1− ⎜ ⎟ + j ⎝100 ⎠ 500 2 is a pair of straight lines and ω p = 100 . For low frequency ( ω ω p ), it’s a straight line with a slope of 0dB. For high frequency ( ω ω p ), it’s a straight line with a slope of -40dB. These two asymptotes intersect at ω = ω p , as shown (dotted line). Then, applying composition rules to get the final magnitude asymptote: dashed line plus dotted line, as shown (solid line). gain factor gain factor 50 0 -50 -100 -10 -20 -30 -40 -50 -60 10 0 10 0 (2). Phase asymptote 10 1 10 1 10 2 ω 10 2 The phase asymptote from zero j 500 ω is a straight line with a slope of 0 at phase π equals , as shown (dashed line). 2 The phase asymptote from pole ω ⎛ ω ⎞ ω 1− ⎜ ⎟ + j ⎝100 ⎠ 500 2 10 3 10 3 10 4 10 4 contains three segments and

The dB-scale magnitude asymptote from zero j<br />

500<br />

ω is a straight line with a slope of<br />

20dB and go through (500,0), as shown (dashed line).<br />

The dB-scale magnitude asymptote from pole<br />

⎛ ω ⎞ ω<br />

1−<br />

⎜ ⎟ + j<br />

⎝100 ⎠ 500<br />

2<br />

is a pair of straight<br />

lines and ω p = 100 . For low frequency ( ω ω p ), it’s a straight line with a slope of<br />

0dB. For high frequency ( ω ω p ), it’s a straight line with a slope of -40dB. These<br />

two asymptotes intersect at ω = ω p , as shown (dotted line).<br />

Then, applying composition rules to get the final magnitude asymptote: dashed line<br />

plus dotted line, as shown (solid line).<br />

gain factor<br />

gain factor<br />

50<br />

0<br />

-50<br />

-100<br />

-10<br />

-20<br />

-30<br />

-40<br />

-50<br />

-60<br />

10 0<br />

10 0<br />

(2). Phase asymptote<br />

10 1<br />

10 1<br />

10 2<br />

ω<br />

10 2<br />

The phase asymptote from zero j<br />

500<br />

ω is a straight line with a slope of 0 at phase<br />

π<br />

equals , as shown (dashed line).<br />

2<br />

The phase asymptote from pole<br />

ω<br />

⎛ ω ⎞ ω<br />

1−<br />

⎜ ⎟ + j<br />

⎝100 ⎠ 500<br />

2<br />

10 3<br />

10 3<br />

10 4<br />

10 4<br />

contains three segments and

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