類比通訊系統2008/11/24 金正元
Outline
• Introduction• Transmission Line• Filter• Amplifier• Mixer
Introduction
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980MHz
900MHz
Introduction
Crystal Oscillator at 100MHz and BPF
900MHz
Introduction
What’s Transmission Line?
• A transmission line is the material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy, such as electromagnetic waves or acoustic waves, as well as electric power transmission. Components of transmission lines include wires, coaxial cables, dielectric slabs, optical fibers, electric power lines, and waveguides.
Miscellaneous Transmission Lines
Design
• 中心頻率 (980MHz)• 傳輸線結構 (microstrip
line)• 板材 (FR4)• 板子厚度 (0.8 mm)• 特徵阻抗 (50 ohm)
Design
Relative Permittivity
0
,
, 4
1
4.6
r
r air
r FR
How about microstrip line ?
, , 4r air eff r FR
Relative Permittivity
0
0
3.407
300
( , )
eff
eff eff
eff
cv f
f
f in GHz in mm
Filter
• Why do we need a filter?
Filter Types
Filter Types
Filter Types
• Maximally flat• Equal-ripple• Linear phase
Filter Types
• Lumped• Distributed
Coupled-Line Filter
Each section is 0.25 lambda long.
Coupled-Line Filter
3.407
0.98
300 141.46
4
eff
eff
f
f
4
It is very close to the practical value 42.4 !!
We can use this formula to calculate our effective relative permittivity.
Amplifier
Amplifier
• R1: bias• C1: input match• C2: output match• C3: 900MHz short• C4: RF decoupling
Layout of Amplifier
in
out
150pF
150pF
27pF
1nF
3.3k
10
150
Vcc
in
out
150pF
150pF
27pF
1nF
3.3k
10
150
Vcc
Mixer
• Mixer = Multiplier !?• Active• Nonlinear
2 30 1 2 3
1 2
y a a x a x a x
x px qx
Diode Mixer
FET Mixer
Layout of Mixer
The End
*^.<*
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