TRANSMISSION LINES,
MATCHING, AND CROSSTALK
Kenneth L. Kaiser
Kettering University
Flint, Michigan
@
Taylor &. Francis
Taylor & Francis G r o u p
Boca Raton
London
N e w York
A CRC title, part of the Taylor & Francis imprint, a member of the
Taylor & Francis Group, the academic division of T&F Informa plc.
Contents
1
Electrical Length
1.1
1.2
1.3
1.4
1.5
1.6
1.7
2
1-1
1-2
1-3
1-5
1-5
1-5
1-6
Cable Modeling
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
2.13
2.14
2.15
2.16
2.17
2.18
2.19
2.20
2.21
3
Electrical Length vs. Physical Length
Standing Waves
Antenna Effects and Effective Permittivity
Unshielded Conductor Radiation
PCB Trace Radiation
Electrically-Large Car
Properties of Electrically-Small Metallic Objects
Purpose of a Cable
High-Fidelity Speaker Wire Candidates
Selecting the Cable Model
Failure of the Lumped-Circuit Model
Characteristic Impedance
Characteristic Impedance of a de Power Bus
Reducing the Characteristic Impedance
Influence of Dielectric Constant
Coax and Twin-Lead
Thinly Coated Twin-Lead
Beads in Coax
Dielectric Resistance and Insulators
Cable Capacitance and Audio Cables
Grounding Strap Impedance
ESD Signal Wire Guideline
TwistedPair
When the Line Can Be Ignored
Line Resonance
Multiple Receiver Loading
Proximity Effect
Characteristic Impedance Formula
2-1
2-3
2-6
2-10
2-10
2-14
2-20
2-20
2-21
2-25
2-30
2-31
2-33
2-34
2-40
2-42
2-45
2-46
2-47
2-50
2-52
Transmission Lines and Matching
3.1
3.2
Voltage Reflection and Transmission Coefficients
Impedance Mismatch
3-1
3-2
ix
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
3.13
3.14
3.15
3.16
3.17
3.18
3.19
3.20
3.21
3.22
3.23
3.24
3.25
3.26
3.27
3.28
3.29
3.30
3.31
3.32
3.33
3.34
3.35
3.36
3.37
3.38
3.39
3.40
3.41
3.42
3.43
3.44
3.45
3.46
VSWRandSWR
The Cost of a VSWR > 1
Distinguishing between the Load and Source
Transient and Steady-State Input Impedance
Transient Reflections
Matching at the Receiver and its Cost
Shunt Matching with Distributed Receivers
Microstrip Branching
Shunt Diode Matching
Shunt RC Matching
Matching at the Driver and its Cost
Series Matching with Multiple Receivers
Effects of Nonzero Source and Load Reflection Coefficients
Signal Bounce as a Function of Time
SettlingTime
Settling Time vs. Reflection Coefficient
Receiver Voltage when Rise Time = Line Delay
Receiver Voltage when Rise Time « Line Delay
Receiver Voltage when Rise Time » Line Delay
Advanced Transient Problem
Ringing in Lumped Circuits
More Shunt Matching
Shunt Matching with a Split Termination for a TTL System
Shunt Matching with a Split Termination for a CMOS System
Shunt Matching with a Split Termination for an ECL System
Split-Termination Equivalent
Experimentally Determining the Line Impedance
Series Matching and Dynamic Output Resistance
Driver Current for Series and Shunt Matching
Summary of Matching Methods
Relationship Between Sinusoidal Input and Output Voltage
The Sinusoidal Current Expression
The Sinusoidal Input Impedance
Coaxial Cable Branching
"Y" Splitter for "Hair-Ball" Networks
Stub Tuning
Inductive Loading
Low-Loss Lines and Short Lines
Inductive Line
Capacitive Line
The Lossy Expressions for Sinusoidal Steady-State
Telephone Lines and the "RC" Region
Transmission Line Parameter Expressions
S Parameters
3-3
3-7
3-8
3-9
3-11
3-13
3-15
3-16
3-18
3-19
3-23
3-25
3-28
3-29
3-30
3-32
3-33
3-35
3-37
3-38
3-42
3-42
3-44
3-47
3-47
3-49
3-50
3-51
3-54
3-55
3-56
3-60
3-62
3-65
3-67
3-69
3-75
3-79
3-84
3-87
3-89
3-91
3-95
3-99
3.47
3.48
3.49
3.50
3.51
Using the Sinusoidal Reflection Coefficient for Transient Problems
Effect of Receiver Capacitance on Transient Behavior
Complete Reflection due to Excessive Capacitance
Amplitude of Mismatch "Blimp" from Receiver Capacitance
When not to Match!
3-105
3-106
3-107
3-107
3-110
Passive C o n t a c t P r o b e s
4.1
Low-Impedance Passive Probe
4.2
Improved Model of the Low-Impedance Passive Probe
4.3
Operating Range of the Low-Impedance Passive Probe
4.4
Improved Model of the Cable and Scope
4.5
High-Impedance Passive Probe
4.6
Input Impedance of a High-Impedance Passive Probe
4.7
High-Impedance Probe Compensator
4.8
Testing with a Square Wave
4.9
Effect of Inductance on the Probe
4-1
4-2
4-4
4-4
4-7
4-9
4-10
4-13
4-17
Cable
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
5.11
5.12
5.13
5.14
5.15
5.16
5.17
5.18
5.19
5.20
5.21
5.22
5.23
5.24
5.25
5.26
5-1
5-6
5-12
5-13
5-17
5-19
5-22
5-24
5-26
5-27
5-31
5-33
5-35
5-38
5-38
5-48
5-54
5-57
5-59
5-62
5-63
5-64
5-65
5-65
5-69
5-73
Shielding and Crosstalk
Best Cable to Reduce Magnetic Noise
Connecting Balanced and Unbalanced Systems
Bicoaxial Line
Reducing Noise Through Transformers
Modeling a Cable as a Transformer
Break Frequency of Coax
Multiple Grounding Points for Coax
Keeping Noise off the Shield
Switching the Neutral and Hot Wires
Avoiding Ground Loops and Hum
Multipoint and Hybrid Grounding
Dynamic Range Between Systems
Multiple Returns in Ribbon Cable
Loose Wires as a Cable
Transfer Impedance
Loss Impedances and Transfer Admittance
The Coupling Model
Pigtails and Connectors—Weak Links in a System
Capacitive or Inductive Crosstalk?
Measurement Tools
Susceptibility of High and Low Resistances
Susceptibility of Scopes
Foam Encapsulation
Inductive Crosstalk and the 3-W Guideline
Capacitive Crosstalk and the 3-W Guideline
Long Lines vs. Close Lines
5.27
5.28
5.29
5.30
5.31
5.32
5.33
6" Guideline for Telephone Lines
Four-Conductor Trace Layout
377 Q Guideline
Why Twisting Often Helps
RC Circuit and Crosstalk
Summary of Methods to Reduce Crosstalk
Fiber's Weakness
5-75
5-76
5-81
5-83
5-89
5-92
5-93
Radiated Emissions and Susceptibility
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
6.10
6.11
6.12
6.13
6.14
6.15
6.16
6.17
Radiated or Conducted Vehicle Interference?
The Automobile Noise Mystery
Copper Plane Addition
Emissions from Twin-Lead Line
Differential-Mode Current Emissions from Twin-Lead Line
Common-Mode Current Emissions from Twin-Lead Line
Reducing Emission Levels
Susceptibility of Twin-Lead Line
Small-Loop and Hertzian Dipole Models
Neglecting the Capacitance and Inductance
Probe Lead Pickup
WaveEquation
Susceptibility of Electrically-Long Twin-Lead Line
Susceptibility of Electrically-Long Wire Above a Ground Plane
Theoryof Current Probes
Loaded Current Probe
Transfer Impedance of Current Probes
References
Index
6-1
6-2
6-6
6-7
6-9
6-10
6-11
6-13
6-17
6-20
6-21
6-25
6-27
6-35
6-44
6-55
6-59
R"l
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