Introduction to RF Design

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??????Introduction to RF Design

• ???

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Outline

• RF Fundamental Theory
• RF Transceivers
• Devices and Characterization

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RF Fundamental Theory

• Introduction
• Two-Port Network Representations
• Transmission Lines
• Scattering Parameters
• Smith Charts
• Noise Parameters
• Nonlinear Distortion

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What is Radio Frequency ?

• Microwave Frequency
• frequency 1 GHz 300 GHz
• wave length 30cm 1mm
• Radio Frequency
• frequency several hundred MHz to low microwave
  frequency band

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IEEE Frequency Band
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High Frequency Considerations

• Frequency limit depends upon the SIZE of
  structures.
• Pure circuit elements (R, L, C) are hard to
  realize because of the PARASITIC elements
• Elements are best regarded of DISTRIBUTED lines.
• Skin Effect

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Skin Effect

• The current concentrates at the surface of the
  conductor due to the magnetic field at the center
  of the conductor
• Skin Depth

Js
d
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Why is 50-W matching ?

• The I/O impedance of filters and antenna are
  usually 50 W .
• Compromise between maximum power handling and
  attenuation of coaxial cables
• Maximum power-handling capability at 30 W of
  coaxial cables
• Minimum attenuation at 77 W of coaxial cables

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Two-Port Network Representations

• Low Frequency Network Parameters

Impedance Matrix
Admittance Matrix
Chain Matrix
Hybrid Matrix
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Network Parameter Properties

• Series Connection

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Network Parameter Properties

• Shunt Connection

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Network Parameter Properties

• Cascade Connection

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Types of Transmission Line
I1
I2
V1
V2
Two-wire line
I1
I2
Co-axial line
V1
V2
I1
I2
Micro-strip line
V1
V2
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Transmission Line Eqn. Sol.
(1)
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Transmission Line Eqn. Sol.
(2)
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Transmission Line Eqn. Sol.
(3)
(4)
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Transmission Line Eqn. Sol.
Attenuation Constant
(5)
Propagation Constant
(6)
(7)
(8)
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Wave Characteristics
(8)
(9)
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Incident and Reflected Waves
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Transmission Line Coordinate
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Reflection Coefficient
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Impedance Transformation
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Impedance Transformation
ZIN(L)Zo
ZIN(l /4)Zo2/ ZL
ZL Zo
ZL
Zo
Zo
d l /4
d 0
d L
d 0
Zmatch(d) Zo
Matched Transmission Line
Quarter-wave Transmission Line
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Impedance Transformation
ZIN(L) -j Zocotb L
ZIN(L)jZotanb L
ZL?
ZL 0
Zo
Zo
d 0
d L
d 0
d L
Zoc(d) -j Zocotb d
Zsc(d) j Zotanb d
Open-circuited Transmission Line
Short-circuited Transmission Line
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Scattering Parameters
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Scattering Parameters
Port2
Port1
a1
a2
Two port Network
b1
b2
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Construction of Smith Chart

• Impedance Plane ?Reflection Coefficient Plane

x
V
x
V
r
U
r
U
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Properties of Smith Chart
Inductor
Short circuit
inductive
Open circuit
capacitive
Capacitor
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Properties of Smith Chart
Shunt Elements
Series Elements
Z-Smith Chart
Y-Smith Chart
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Impedance Matching
A
B
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Impedance Matching
C
D
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Noise Parameter

• Noise Figure and Noise Temperature
• Noisy Two Port Description
• Noise Figure of Cascade Networks

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Noise Factor/Noise Figure

• Definition
• Noise Factor
• Noise Figure

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Noise Temperature

• Input Noise Power
• Thermal noise of the source
• Reference temperature
• Available noise power at output

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Noise Figure of Cascade Networks
N1
Ntot,1
Ntot
Gtot Ftot
Ntot,2
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Nonlinear Distortion

• Harmonic Distortion
• Two-tone Intermodulation Distortion
• IP3 of Cascade Networks
• Dynamic Range

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Linear System

• What is a Linear System ?
• What is Odd Symmetry ?

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Harmonics Distortion
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Harmonic Distortion

• Gain Compression

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Harmonic Distortion

• Third Order Harmonic Intercept

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Harmonic Distortion

• Desensitization and Blocking

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Two-tone Distortion

• Intermodulation

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Two-tone Distortion

• 3rd Order Intermodulation Intercept Point (IP3)

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3rd Order IM Intercept Point (IP3)
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IP3 of Cascade Networks

• IP3 of Cascade Networks

G2 IP32
Gtot IP3output
G1 IP31
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Dynamic Range
Pout
1dB
Psf,out
DRsf
DR1dB
PIM,out
DP
DP
DP
Pin
PIIP3
Psf,in
Pin,min
If Pin,min PIM,in input Noise floor
P1dB,in