Transmission Lines in Digital Systems for EMC Practitioners

ISBN-13: 9781118143995 / Angielski / Twarda / 2011 / 288 str.

Clayton R. Paul

Opis

This is a brief but comprehensive book covering the set of EMC skills that EMC practitioners today require in order to be successful in high-speed, digital electronics. The basic skills in the book are new and weren't studied in most curricula some ten years ago. The rapidly changing digital technology has created this demand for a discussion of new analysis skills particularly for the analysis of transmission lines where the conductors that interconnect the electronic modules have become -electrically large, - longer than a tenth of a wavelength, which are increasingly becoming important. Crosstalk between the lines is also rapidly becoming a significant problem in getting modern electronic systems to work satisfactorily. Hence this text concentrates on the modeling of -electrically large- connection conductors where previously-used Kirchhoff's voltage and current laws and lumped-circuit modeling have become obsolete because of the increasing speeds of modern digital systems. This has caused an increased emphasis on Signal Integrity. Until as recently as some ten years ago, digital system clock speeds and data rates were in the hundreds of megahertz (MHz) range. Prior to that time, the -lands- on printed circuit boards (PCBs) that interconnect the electronic modules had little or no impact on the proper functioning of those electronic circuits. Today, the clock and data speeds have moved into the low gigahertz (GHz) range.

Spis treści

Preface xi

1 Transmission Lines: Physical Dimensions vs. Electric Dimensions 1

1.1 Waves, Time Delay, Phase Shift, Wavelength, and Electrical Dimensions, 4

1.2 Spectral (Frequency) Content of Digital Waveforms and Their Bandwidths, 10

1.3 The Basic Transmission–Line Problem, 22

2 Time–Domain Analysis of Two–Conductor Lines 31

2.1 The Transverse Electromagnetic Mode of Propagation and the Transmission–Line Equations, 32

2.2 The Per–Unit–Length Parameters, 37

2.2.1 Wire–Type Lines, 37

2.2.2 Lines of Rectangular Cross Section, 47

2.3 The General Solutions for the Line Voltage and Current, 50

2.4 Wave Tracing and Reflection Coefficients, 54

2.5 A Simple Alternative to Wave Tracing in the Solution of Transmission Lines, 60

2.6 The SPICE (PSPICE) Exact Transmission–Line Model, 70

2.7 Lumped–Circuit Approximate Models of the Line, 75

2.8 Effects of Reactive Terminations on Terminal Waveforms, 84

2.8.1 Effect of Capacitive Terminations, 85

2.8.2 Effect of Inductive Terminations, 87

2.9 Matching Schemes for Signal Integrity, 89

2.10 Effect of Line Discontinuities, 96

2.11 Driving Multiple Lines, 101

3 Frequency–Domain Analysis of Two–Conductor Lines 103

3.1 The Transmission–Line Equations for Sinusoidal Steady–State (Phasor) Excitation of the Line, 104

3.2 The General Solution for the Line Voltages and Currents, 105

3.3 The Voltage Reflection Coefficient and Input Impedance of the Line, 106

3.4 The Solution for the Terminal Voltages and Currents, 108

3.5 The SPICE Solution, 111

3.6 Voltage and Current as a Function of Position on the Line, 112

3.7 Matching and VSWR, 115

3.8 Power Flow on the Line, 117

3.9 Alternative Forms of the Results, 120

3.10 Construction of Microwave Circuit Components Using Transmission Lines, 120

4 Crosstalk in Three–Conductor Lines 125

4.1 The Multiconductor Transmission–Line Equations, 125

4.2 The MTL Per–Unit–Length Parameters of Inductance and Capacitance, 131

4.2.1 Wide–Separation Approximations for Wires, 135

4.2.2 Numerical Methods, 145

5 The Approximate Inductive Capacitive Crosstalk Model 155

5.1 The Inductive Capacitive Coupling Approximate Model, 159

5.2 Separation of the Crosstalk into Inductive and Capacitive Coupling Components, 166

5.3 Common–Impedance Coupling, 172

5.4 Effect of Shielded Wires in Reducing Crosstalk, 173

5.4.1 Experimental Results, 182

5.5 Effect of Shield Pigtails, 183

5.5.1 Experimental Results, 187

5.6 Effect of Multiple Shields, 188

5.6.1 Experimental Results, 188

5.7 Effect of Twisted Pairs of Wires in Reducing Crosstalk, 197

5.7.1 Experimental Results, 203

5.8 The Shielded Twisted–Pair Wire: The Best of Both Worlds, 209

6 The Exact Crosstalk Prediction Model 211

6.1 Decoupling the Transmission–Line Equations with Mode Transformations, 212

6.2 The SPICE Subcircuit Model, 215

6.3 Lumped–Circuit Approximate Models of the Line, 231

6.4 A Practical Crosstalk Problem, 237

Appendix A Brief Tutorial on Using PSPICE 245

Index 267

O autorze

CLAYTON R. PAUL, PhD, is Professor and Sam Nunn Eminent Chair in Aerospace Engineering in the Department of Electrical and Computer Engineering at Mercer University. The author of twelve electrical engineering textbooks, he has also published more than 200 technical papers primarily on the electromagnetic compatibility of electronic systems. Dr. Paul is a Fellow of the IEEE and a member of Tau Beta Pi and Eta Kappa Nu.

Blurb

Learn the new skills needed to work with today′s high–speed digital electronic systems

Following this text′s clear explanations and examples, EMC practitioners will quickly master the new transmission line concepts and skills needed to analyze and design today′s high–speed digital electronic systems. The author focuses on modern transmission lines in which the conductors that interconnect the electronic modules are "electrically long" (i.e., longer than one–tenth of a wavelength). Moreover, throughout the text, the author explores the increasingly important issues of crosstalk and system integrity, helping readers avoid many common pitfalls in the analysis and design of electronic systems.

Transmission Lines in Digital Systems for EMC Practitioners begins with a discussion of the fundamental concepts of waves, wavelength, time delay, and electrical dimensions, and then examines the effect of electrically long conductors on signal integrity. Next, the book explores:

• Time domain analysis of two–conductor lines

• Frequency domain analysis of two–conductor lines

• Crosstalk in three–conductor lines

• Approximate inductive–capacitive crosstalk model for electrically short lines

• Exact crosstalk prediction model

Throughout the text, the PSpice program is used as a computational aid to simulate digital systems and determine crosstalk and system integrity. A quick PSpice tutorial is provided for readers who are unfamiliar with the program. The text also offers numerous illustrations to help readers visualize complex concepts and design methods. In addition, experimental results are set forth to verify mathematical results.

Transmission Lines in Digital Systems for EMC Practitioners is an essential guide for students and engineers who need to keep pace with the growing demand for ever faster digital electronic systems.