Fast Circuit Boards

An essential guide to modern circuit board design based on simple physics and practical applications

The fundamentals taught in circuit theory were never intended to work above a few megahertz, let alone at a gigahertz. While electronics is grounded in physics, most engineers' education in this area is too general and mathematical to be easily applied to the problem of high speed circuits. Left to their own devices, many engineers produce layouts that require expensive revisions in order to finally meet specifications.

Fast Circuit Boards fills the gap in knowledge by providing clear, down-to-earth guidance on designing digital circuit boards that function at high clock rates. By making the direct connection between physics and fast circuits, this book instills the fundamental universal principles of information transfer to give engineers a solid basis for hardware design. Using simple tools, simple physics, and simple language, this invaluable resource walks through basic electrostatics, magnetics, wave mechanics, and more to bring the right technology down to the working level.

Designed to be directly relevant and immediately useful to circuit board designers, this book:

• Properly explains the problems of fast logic and the appropriate tools
• Applies basic principles of physics to the art of laying out circuit boards
• Simplifies essential concepts scaled up to the gigahertz level, saving time, money, and the need for revisions
• Goes beyond circuit theory to provide a deep, intuitive understanding of the mechanisms at work
• Demonstrates energy management's role in board design through step function-focused transmission line techniques

Engineers and technicians seeking a more systematic approach to board design and a deeper understanding of the fundamental principles at work will find tremendous value in this highly practical, long-awaited text.

Auteur

RALPH MORRISON, MS, EE, is a consultant and lecturer in the area of interference control and electronics. As the former president of Instrum, he has thirty years of design and consulting experience, and is the author of Noise and Other Interfering Signals, Grounding and Shielding in Facilities, and Solving Interference Problems in Electronics.

Contenu

Preface ix 1 Electric and Magnetic Fields 1 1.1 Introduction 2 1.2 Electrons and the Force Field 8 1.3 The Electric Field and Voltage 11 1.4 Electric Field Patterns and Charge Distributions 14 1.5 Field Energy 17 1.6 Dielectrics 19 1.7 Capacitance 20 1.8 Capacitors 21 1.9 The D or Displacement Field 21 1.10 Mutual and Self Capacitance 22 1.11 Current Flow in a Capacitance 23 1.12 The Magnetic Field 24 1.13 The B Field of Induction 27 1.14 Inductance 28 1.15 Inductors 30 1.16 The Inductance of a Solenoid in Air 32 1.17 Magnetic Field Energy Stored in Space 33 1.18 Mutual Inductance 34 1.19 Transformer Action 35 1.20 Poynting's Vector 35 1.21 Resistors and Resistance 36 Problem Set 39 Glossary 39 Answers to Problems 42 2 Transmission Lines--Part 1 43 2.1 Introduction 43 2.2 The Ideal World 44 2.3 Transmission Line Representations 45 2.4 Characteristic Impedance 47 2.5 Waves and Wave Velocity 48 2.6 The Balance of Field Energies 50 2.7 A Few Comments on Transmission Lines 51 2.8 The Propagation of a Wave on a Transmission Line 51 2.9 Initial Wave Action 53 2.10 Reflections and Transmissions at Impedance Transitions 55 2.11 The Unterminated (Open) Transmission Line 57 2.12 The Short?]Circuited Transmission Line 61 2.13 Voltage Doubling and Rise Time 61 2.14 Matched Shunt Terminated Transmission Lines 64 2.15 Matched Series Terminated Transmission Lines 68 2.16 Extending a Transmission Line 69 2.17 Skin Effect 70 Problem Set 71 Glossary 72 Answers to Problems 74 3 Transmission Lines--Part 2 75 3.1 Introduction 75 3.2 Energy Sources 75 3.3 The Ground Plane/Power Plane as an Energy Source 77 3.4 What Is a Capacitor? 77 3.5 Turning Corners 79 3.6 Practical Transmissions 80 3.7 Radiation and Transmission Lines 81 3.8 Multilayer Circuit Boards 83 3.9 Vias 85 3.10 Layer Crossings 85 3.11 Vias and Stripline 87 3.12 Stripline and the Power Plane 87 3.13 Stubs 88 3.14 Traces and Ground (Power) Plane Breaks 89 3.15 Characteristic Impedance of Traces 89 3.16 Microstrip 90 3.17 Centered Stripline 93 3.18 Asymmetric Stripline 94 3.19 Two?]Layer Boards 95 3.20 Sine Waves on Transmission Lines 95 3.21 Shielded Cables 96 3.22 Coax 97 3.23 Transfer Impedance 97 3.24 Waveguides 100 3.25 Balanced Lines 101 3.26 Circuit Board Materials 101 Problem Set 102 Glossary 102 Answers to Problems 104 4 Interference 105 4.1 Introduction 105 4.2 Radiation--General Comments 106 4.3 The Impedance of Space 107 4.4 Field Coupling to Open Parallel Conductors (Sine Waves) 107 4.5 Cross?]Coupling 108 4.6 Shielding--General Comments 110 4.7 Even?]Mode Rejection 111 4.8 Ground--A General Discussion 112 4.9 Grounds on Circuit Boards 115 4.10 Equipment Ground 116 4.11 Guard Shields 116 4.12 Forward Referencing Amplifiers 117 4.13 A/D Converters 118 4.14 Utility Transformers and Interference 118 4.15 Shielding of Distribution Power Transformers 119 4.16 Electrostatic Discharge 120 4.17 Aliasing Errors 122 Glossary 123 5 Radiation 125 5.1 Introduction 125 5.2 Standing Wave Ratio 126 5.3 The Transmission Coefficient tau 127 5.4 The Smith Chart 127 5.5 Smith Chart and Wave Impedances (Sine Waves) 130 5.6 Stubs and Impedance Matching 133 5.7 Radiation--General Comments 134 5.8 Radiation from Dipoles 134 5.9 Radiation from Loops 136 5.10 Effective Radiated Power for Sinusoids 137 5.11 Apertures 137 5.12 Honeycomb Filters 138 5.13 Shielded Enclosures 139 5.14 Screened Rooms 139 5.15 Line Filters 140 Glossary 141 Appendix A: Sine Waves in Circuits 143 A.1 Introduction 143 A.2 Unit Circle and Sine Waves 143 A.3 Angles, Frequency, and rms 145 A.4 The Reactance of an Inductor 147 A.5 The Reactance of a Capacitor 148 A.6 An Inductor and a Resistor in Series 150 A.7 A Capacitor and a Resistor in Series 151 A.8 The Arithmetic of Complex Numbers 152 A.9 Resistance, Conductance, Susceptance, Reactance, Admittance, and Impedance 153 A.10 Resonance 155 A.11 Answers to Problems 156 Appendix B: Square?]Wave Frequency Spectrum 159 B.1 Introduction 159 B.2 Ideal Square Waves 159 B.3 Square Waves with a Rise Time 161 Appendix C: The Decibel 163 Appendix D: Abbreviations and Acronyms 165 Index