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Notes
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Slides
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Text Book:
[1] Microwave and RF Design of Wireless Systems, David M. Pozar
[2] RF Microelectronics, B. Razavi
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Introduction
Noise and Distortion/Nonlinear Behavior
Transmission Line and Charactristic impedance
S-Parameters and Smith Chart
Amplifiers, Two-Port Power Gain
Design of Amplifiers
Matching Networks and Noise Optimization
Oscillators
Mixers
Modulators/Demodulators
Introduction to Power Amplifiers
Introduction to Phase Lock Loops (PLLs)
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Band
Frequency Range
Wavelength
Applications
LW
30 kHz – 300 kHz
10 km – 1 km
Naval communications
Aircraft avionics
MW
300 kHz – 3 MHz
1 km – 100m
AM Radio
HF
3 MHz – 30 MHz
100 m – 10 m
VHF
30 MHz – 300 MHz
10 m – 1 m
TV Broadcasting, FM Radio
Military Communications
UHF
300 MHz – 3 GHz
1 m – 10 cm
TV Broadcasting, WiFi,
GPS, Mobile
Microwave
3 GHz – 30 GHz
10 cm – 1 cm
Satellite Communications
intercity communications
Millimeter
wave
30 GHz – 300 GHz
1 cm – 1 mm
Satellite Communications
Inter-Satellite Communications
SW Radio
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vo = a0 + a1vi + a1vi2 + a3vi3 +···
vi
vo
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vi = V0 cos ω0t
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Is gain compression important in all modulation schemes?
Why?
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gain compression is important in Amplitude Modulation
gain compression is not important in Frequency Modulation
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Fundamental components:
Intermodulation products:
*The third-order IM products at 2ω1 - ω2 and 2ω2 - ω1 are of particular interest
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L (Length of the circuit) << λ
The circuit is not very short compared
to wavelength
 The Kirchhoff’s voltage and current laws are approximations that hold only in the
lumped regime.
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A transmission line is used to guide electromagnetic energy from one place to another.
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When conductor become long, because of the phase shift that occurs as the signal
travels down the conductor, the voltage and current will be different at different points
along the conductor.
T-Line as an infinite ladder network:
Solving for Zin
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Ideal T-Line
If |ZY|<<1:
In the case of alossless T-line
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Z=s L dz , Y=s C dz
The input impedance called the characteristic impedance (Z0) for an ideal, lossless
infinite T-Line is therefore:
Z0=
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In a lossy T-Line:
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For very small dz:
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Propagation Constant γ:
For lossless line: α=0
and
β=w(LC)1/2=2π/λ
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Finite Length T-Line
- T-Line with matched termination
Z0
Zin=Z0
ZL=Z0
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Finite Length T-Line
- T-Line with arbitrary termination
Zin=?
Z0
• A signal traveling down the line maintains a ratio
of voltage to current equals to Z0 but the termination
impedance in the load imposes its own ratio of voltage to current.
ZL
The only way to reconcile the conflict is for some of the signal to reflect
back toward the source
The ratio of reflected to incident quantities at the load end of the line is called
Reflection coefficient (ГL):
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Finite Length T-Line
- T-Line with arbitrary termination
The voltage and current at point z along the line may be expressed as:
The impedance at any value of z is:
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Finite Length T-Line
- T-Line with arbitrary termination
If attenuation is negligible:
Special cases:
If L=λ
If L=λ/2
If L=λ/4
then
then
then
Zin=ZL
Zin=ZL
Zin=Z02/ZL
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Scattering Parameters
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S-parameters are a useful method for representing a circuit as a “black box”
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S-param. measurement
Apply an input to port 1:
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S11 = b1 / a1 (reflection coefficient at port 1)
S21 = b2 / a1 (transfer ratio)
Apply an input to port 2:
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S22 = b2 / a2 (reflection coefficient at port 2)
S12 = b1 / a2 (transfer ratio)
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Reflection coefficients
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Reflection coefficients at the output:
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Ranges from -1 (ZL=0) to 1 (ZL=inf.)
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Reflection coefficients at the input:
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Input and output impedances can also be derived from Sparameters:
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Smith chart
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Y=G+jB
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