推 ketsu1109 :已收入精華區 04/07 22:58
課程名稱︰微波電路
課程性質︰選修
課程教師︰瞿大雄
開課學院：電信所
開課系所︰電信所
考試日期（年月日）︰2009/04/07
考試時限（分鐘）：60min
是否需發放獎勵金：是
（如未明確表示則不予發放）
試題 :
A 2-port MESFET transistor has the simplified equivalent circuit at 1GHz as
shown in Fig.1
Gate ──┐ ┌───┬──Drain
1 │ + ╱╲ │ 5
port1 ─pF ┴ ﹤↓ ﹥ ┴ ─ pF port2
2π ┬ Vgs ╲╱2Vgs ┬ π
│ - │ │
┌> ──┴───┴───┴── <┐
│ Source │
Zin Zout Fig.1
(a) (20%) Derive its 2-port S-parameters at 1GHz (Zo=50Ω)
(b) (10%) Plot the normalized impedances z_in and z_out relative to Zo=50Ω
on the attached Smith chart and calculate the corresponding VSWR values.
(c) (5%) Find the input and output conjugate matching loads of this MESFET.
(d) (10%) Can one design the input and output lossless matching circuits to
match a 50Ω load and a 50Ω source? If "yes", give your design using the
attached Smith chart. If "No", give your explanation.
(e) (5%) Plot the signal flow graph of this MESFET.
(f) (10%) Find the input reflection coefficient Γ_in, if this MESFET is
terminated with a 40Ω load.
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