課程名稱︰電路學
課程性質︰必修
課程教師︰陳信樹
開課學院：電資學院
開課系所︰電機系
考試日期（年月日）︰2011/12/21
考試時限（分鐘）：50min
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1.
In the circuit shown in Fig.1,a load resistor R_L is placed in parallel
with the inductor L of a RL filter.
(a)
(10%) Determine the transfer function.Is it a low-pass filter or high-pass
filter?What are its gain K and cutoff frequency ω_co ?
(b)
(20%) Sketch the amplitude ratio and phase shift plots fort the loaded RL
filter with R=R_L=500Ω , and L=5.31mH.On the same amplitude ratio plot,sketch
the amplitude ratio for the unloaded RL filter(i.e. R_L→∞).Please calculate
and mark their gain K and cutoff frequency ω_co on the plot.
(c)
(10%) If a voltage input v_i(t)=10 cos(ω_1 t)+10 cos(ω_2 t),where ω_1 and
ω_2 are 2π X 3.75 kHz and 2π X 30K kHz respectively, is given,what is
the output v_o(t)?
R
───■──────── +
+ │ │ │
○ v_i ◆ L R_L ■ v_0
- │ │ │ -
────────────
Fig.1
2.
In the circuit shown in Fig.2 ,a voltage input with a nonzero source
resistance R_i is connected to a series RLC bandpass filter.
(a)
(10%) Determine the transfer function.What are its midband gain K and
-3dB bandwidth B?
(b)
(20%) Sketch the amplitude ratio plot for the circuit in Fig.2 with
R=R_i=143.24Ω , C=1uF and L=2.533mH. On the same plot,sketch the amplitude
ratio for the circuit with R_i=0.Please calculate the ,ark their midband
gain K and cutoff frequencies ω_l ω_u on the plot.What are their quality
factors Q ?
R_i L C
─■──▼──||──
+ │ │+
○ v_i R ■ v_0 Fig.2
- │ │-
──────────
3.
(30%)Draw the asymptotic Bode plot of the gain and phase for
s(s+800)
H(s)=─────────
(s+50)(s+200)
Then add the dB corrections to find the maximum value of a(ω) and the ω_t
and ω_u which the gain drops 3dB below the maximum.Please mark these values
on tje plot.
一百學年度第一學期Fall 2011 12/21/2011
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