Fast Circuit Boards: Energy Management

Table of Contents

Cover

Title Page

Preface

1 Electric and Magnetic Fields

1.1 Introduction

1.2 Electrons and the Force Field

1.3 The Electric Field and Voltage

1.4 Electric Field Patterns and Charge Distributions

1.5 Field Energy

1.6 Dielectrics

1.7 Capacitance

1.8 Capacitors

1.9 The D or Displacement Field

1.10 Mutual and Self Capacitance

1.11 Current Flow in a Capacitance

1.12 The Magnetic Field

1.13 The B Field of Induction

1.14 Inductance

1.15 Inductors

1.16 The Inductance of a Solenoid in Air

1.17 Magnetic Field Energy Stored in Space

1.18 Mutual Inductance

1.19 Transformer Action

1.20 Poynting’s Vector

1.21 Resistors and Resistance

Problem Set

Glossary

Answers to Problems

2 Transmission Lines—Part 1

2.1 Introduction

2.2 The Ideal World

2.3 Transmission Line Representations

2.4 Characteristic Impedance

2.5 Waves and Wave Velocity

2.6 The Balance of Field Energies

2.7 A Few Comments on Transmission Lines

2.8 The Propagation of a Wave on a Transmission Line

2.9 Initial Wave Action

2.10 Reflections and Transmissions at Impedance Transitions

2.11 The Unterminated (Open) Transmission Line

2.12 The Short‐Circuited Transmission Line

2.13 Voltage Doubling and Rise Time

2.14 Matched Shunt Terminated Transmission Lines

2.15 Matched Series Terminated Transmission Lines

2.16 Extending a Transmission Line

2.17 Skin Effect

Problem Set

Glossary

Answers to Problems

3 Transmission Lines—Part 2

3.1 Introduction

3.2 Energy Sources

3.3 The Ground Plane/Power Plane as an Energy Source

3.4 What Is a Capacitor?

3.5 Turning Corners

3.6 Practical Transmissions

3.7 Radiation and Transmission Lines

3.8 Multilayer Circuit Boards

3.9 Vias

3.10 Layer Crossings

3.11 Vias and Stripline

3.12 Stripline and the Power Plane

3.13 Stubs

3.14 Traces and Ground (Power) Plane Breaks

3.15 Characteristic Impedance of Traces

3.16 Microstrip

3.17 Centered Stripline

3.18 Asymmetric Stripline

3.19 Two‐Layer Boards

3.20 Sine Waves on Transmission Lines

3.21 Shielded Cables

3.22 Coax

3.23 Transfer Impedance

3.24 Waveguides

3.25 Balanced Lines

3.26 Circuit Board Materials

Problem Set

Glossary

Answers to Problems

4 Interference

4.1 Introduction

4.2 Radiation—General Comments

4.3 The Impedance of Space

4.4 Field Coupling to Open Parallel Conductors (Sine Waves)

4.5 Cross‐Coupling

4.6 Shielding—General Comments

4.7 Even‐Mode Rejection

4.8 Ground—A General Discussion

4.9 Grounds on Circuit Boards

4.10 Equipment Ground

4.11 Guard Shields

4.12 Forward Referencing Amplifiers

4.13 A/D Converters

4.14 Utility Transformers and Interference

4.15 Shielding of Distribution Power Transformers

4.16 Electrostatic Discharge

4.17 Aliasing Errors

Glossary

5 Radiation

5.1 Introduction

5.2 Standing Wave Ratio

5.3 The Transmission Coefficient τ

5.4 The Smith Chart

5.5 Smith Chart and Wave Impedances (Sine Waves)

5.6 Stubs and Impedance Matching

5.7 Radiation—General Comments

5.8 Radiation from Dipoles

5.9 Radiation from Loops

5.10 Effective Radiated Power for Sinusoids

5.11 Apertures

5.12 Honeycomb Filters

5.13 Shielded Enclosures

5.14 Screened Rooms

5.15 Line Filters

Glossary

Appendix A: Sine Waves in Circuits

A.1 Introduction

A.2 Unit Circle and Sine Waves

A.3 Angles, Frequency, and rms

A.4 The Reactance of an Inductor

A.5 The Reactance of a Capacitor

A.6 An Inductor and a Resistor in Series

A.7 A Capacitor and a Resistor in Series

A.8 The Arithmetic of Complex Numbers

A.9 Resistance, Conductance, Susceptance, Reactance, Admittance, and Impedance

A.10 Resonance

A.11 Answers to Problems

Appendix B: Square‐Wave Frequency Spectrum

B.1 Introduction

B.2 Ideal Square Waves

B.3 Square Waves with a Rise Time

Appendix C: The Decibel

Appendix D: Abbreviations and Acronyms

Index

End User License Agreement

List of Tables

Chapter 01

Table 1.1 The relative dielectric constant for materials used in electronics.

Table 1.2 The resistivity of common conductors.

Table 1.3 Ohms‐per‐square for copper and iron.

List of Illustrations

Chapter 01

Figure 1.1 The forces between charges. (a) Repelling force and (b) attracting force.

Figure 1.2 Equipotential surfaces around a charged sphere.

Figure 1.3 (a)–(c) Electric field configurations around a shielded conductor.

Figure 1.4 The electric field pattern of a circuit trace over a ground plane.

Figure 1.5 The electric field pattern in the presence of a dielectric.

Figure 1.6 The mutual capacitances between traces over a ground plane.

Figure 1.7 The voltage on a capacitor when supplied a steady current.

Figure 1.8 The magnetic field H around a current carrying conductor.

Figure 1.9 The H field in and around a solenoid.

Figure 1.10 A voltage induced into a moving coil.

Figure 1.11 An inductor driven from a constant voltage source.

Figure 1.12 The inductance of round copper conductors.

Figure 1.13 A magnetic circuit with an air gap.

Figure 1.14 Ferrite cup core construction.

Figure 1.15 A trace over a conducting plane showing fields.

Figure 1.16 Poynting’s vector for parallel conductors carrying power.

Chapter 02

Figure 2.1 The lumped parameter model of a transmission line. L is inductance per unit length. C is capacitance per unit length.

Figure 2.2 The field pattern around a trace over a ground plane (microstrip).

Figure 2.3 The flow of current in a wave as it moves along a transmission line.

Figure 2.4 The wave action associated with a transmission line shunt terminated in its characteristic impedance.

Figure 2.5 The wave action on a transmission line shunt terminated in its characteristic impedance.

Figure 2.6 The voltage waveforms on an ideal open circuit transmission line for a step input voltage. (a) Individual waves and (b) The sum of the waves.

Figure 2.7 The voltage waveforms on an ideal open circuit transmission line for a step input voltage.

Figure 2.8 The voltage pattern of waves on a short‐circuited transmission line. (a) Individual waves and (b) The sum of the waves.

Figure 2.9 The staircase current pattern for a shorted transmission line.

Figure 2.10 Rise times and the reflections from an unterminated transmission line.

Figure 2.11 Matching shunt termination using a remote switch.

Figure 2.12 A matching termination using a remote switch.

Figure 2.13 The voltage at a termination when there is a mismatch in impedances.

Figure 2.14 The voltage at a termination when there is a mismatch in terminating impedance.

Figure 2.15 A series (source) terminated transmission line.

Figure 2.16 A typical transmission line.

Chapter 03

Figure 3.1 The first energy sources when a logic trace is connected to the nearest power conductor.

Figure 3.2 Wave action for a simple logic transmission. Note: Each wave is on a different time scale.

Figure 3.3 A four‐layer board layup.

Figure 3.4 (a) and (b) Two four‐layer board configurations.

Figure 3.5 An acceptable six‐layer board configuration.

Figure 3.6 (a) A via crossing conducting planes with radiation and (b) Two vias crossing conducting planes.

Figure 3.7 Using vias in the transition from stripline to microstrip.

Figure 3.8 The return current path for stripline when a power plane is used.

Figure 3.9 The delay caused by a stub on a transmission line.

Figure 3.10 Microstrip geometry.

Figure 3.11 Microstrip parameters. Constant characteristic impedances for trace thickness of 1.5 mils.

Figure 3.12 Microstrip parameters. Constant characteristic impedances for a trace thickness of 2 mils.

Figure 3.13 Microstrip parameters. Constant characteristic impedances for a trace thickness of 2.7 mils.

Figure 3.14 Embedded microstrip geometry.

Figure 3.15 Centered stripline. Curves of constant characteristic impedance for a trace thickness of 1.5 mils.

Figure 3.16 Asymmetric stripline.

Figure 3.17 Trace pattern for use on a two‐sided board.

Figure 3.18 The characteristic impedance of a coaxial geometry.

Figure 3.19 Transfer impedance test for a coaxial cable.

Figure 3.20 The transfer impedance for several standard cables.

Chapter 04

Figure 4.1 Field coupling to parallel conductors (wires).

Figure 4.2 The mutual capacitance and mutual inductance between two transmission lines.

Figure 4.3 A step‐function wave applied to a culprit line.

Figure 4.4 Inductive coupling between transmission lines.

Figure 4.5 The termination of a balanced transmission line.

Figure 4.6 A differential amplifier using a guard shield.

Figure 4.7 A forward referencing amplifier.

Figure 4.8 A single‐phase isolation transformer. (a) One shield, (b) two shields, and (c) three shields.

Chapter 05

Figure 5.1 A standing wave pattern.

Figure 5.2 An impedance Smith chart showing the relation between the reflection coefficients and terminations on a 1‐ohm transmission line.

Figure 5.3 (a) The paths taken on a Smith chart to reach the point τ = 1 where x = 0 and r = 1. (We first added a shunt capacitor.) and (b) The paths taken on a Smith chart to reach the point τ = 1 where x = 0 and r = 1. (We first added a shunt inductor.)

Figure 5.4 The E and H field intensities near a half‐dipole antenna.

Figure 5.5 The E and H field intensities near a radiating loop.

Appendix 01

Figure A.1 The unit circle and the point (0.5, 0.866).

Figure A.2 A sine and cosine wave.

Figure A.3 Sine wave voltage and current for an inductor. The current lags the voltage by 90°.

Figure A.4 Sine wave voltage and current for a capacitor. The voltage leads the current by 90°.

Figure A.5 The vectors representing the voltages in a series RL circuit.

Figure A.6 The vectors representing the voltages in a series RC circuit.

Appendix 02

Figure B.1 The harmonics that make up a square wave.

Figure B.2 The harmonics that make up a square wave plotted linearly and on a logarithmic scale.

Figure B.3 The harmonics of a square wave with a finite rise time.

Fast Circuit Boards

Energy Management

Ralph Morrison

This edition first published 2018

© 2018 John Wiley & Sons, Inc.

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Library of Congress Cataloging‐in‐Publication Data

Names: Morrison, Ralph, author.

Title: Fast circuit boards : energy management / by Ralph Morrison.

Description: Hoboken, NJ : John Wiley & Sons, 2018. | Includes index. |

Identifiers: LCCN 2017037713 (print) | LCCN 2017046159 (ebook) | ISBN 9781119413929 (pdf) | ISBN 9781119413998 (epub) | ISBN 9781119413905 (cloth)

Subjects: LCSH: Very high speed integrated circuits–Design and construction. | Logic design.

Classification: LCC TK7874.7 (ebook) | LCC TK7874.7. M67 2018 (print) | DDC 621.31–dc23

LC record available at https://lccn.loc.gov/2017037713

Cover Design: Wiley

Cover Image: © troyek/Getty Images

Preface

If you are reading this preface you are probably involved in designing and laying out logic circuit boards. I have a story to tell you which you will not find on the internet or in other books. What I have to say has been put to practice and it works. It is not complicated but it is different. In this book, I ask you to go back to the basics so that I can explain the future. I hope you are willing to put forth the effort to go down this path.

I would like to thank my wife Elizabeth for her encouragement and help. She never complained when I spent days on end at my computer writing and rewriting. It takes a lot of dedicated time to write a book.

I would like to thank Dan Beeker of NXP Semiconductors. He is a principal engineer in Automotive Field Engineering. I have given many seminars arranged by Dan over the years. Using the material in my seminars he has been very effective in helping designers avoid problems. His experiences are proof that the material in this book, when put to practice, really works. His success has spurred me on. Highlights of this understanding are blocked out in the text as Insights.

This book presents some ideas that I have not seen in print or heard at conferences. I know that this does not prove that these ideas are new or novel. It could mean that I have not talked to the right people. My contact with engineers tells me they mainly come out of the same molds in school. The basic math and physics that is taught revolves around differential equations that in most cases solve problems using numerical techniques.

Computers work well in antenna design and in moving energy in wave guides. For a long time the problem of wiring circuit boards has been considered trivial and has not received very much attention. One of the reasons is that people have been getting by. That is no longer the case and it is time for a change. A big part of the problem is that sine waves and antenna or microwave design methods are not a fit for transmission lines on circuit boards where step functions, delays, and reflections take center stage.

To whet your appetite here are a few ideas that are treated in this book:

Logic is the movement of energy

Not all waves carry energy

We cannot measure moving field energy directly

Waves deposit, convert and move electric and magnetic field energy on transmission lines

Radiation only occurs on leading edges

Energy in motion is half electric and half magnetic

Via positioning controls radiation

Transmission lines can oscillate

Waves can convert stored electric field energy to stored magnetic field energy

Waves can convert stored magnetic field energy to stored electric field energy

Waves can convert stored energy into moving energy

In my career I have written 14 books, all published by John Wiley &Sons. I am 92 and I have been retired for some 25 years. That has not stopped me from giving seminars, doing consulting, and writing books. I often reflect on what keeps my writing and how I seem to be almost singular in my approach to interference issues. A lot has to do with the opportunities given to me in my career. Since this will probably be my last book I thought this would be an opportunity to provide the readers with some of my personal background. A lot of people have helped me over the years and my story is unique.

I was born in Highland Park, a suburb of Los Angeles, California on January 4, 1925 to immigrant parents who had no understanding or interest in science. I grew up in the great depression of the thirties when a cup of coffee was 5 cents. Cellophane and zippers were not a part of life. The last horse‐drawn carriages brought fresh vegetables to our street. There was the ice man and houses had ice boxes. Raw or pasteurized milk was delivered in bottles by the milkman before I got up. Radios blared soap operas all day.

My early experiences with things electrical were crystal sets, radios, and building an audio amplifier. I learned how to measure voltage and calculate current flow. I used an oscilloscope in school to observe circuit voltages. I observed magnetics in terms of loud speakers, motors, and transformers. I formed images of current flow and voltage patterns. I knew about radio transmission and antennas from my amateur radio friends, but this area was a mystery to me. It was not until I entered college that I was introduced to electromagnetic fields. By then I had enough mathematics to work a few simple problems but my understanding of the electrical world was still very limited.

I started playing violin at age 4½ and my father got me a scholarship. I walked a mile to elementary school and I remember the Maypole in the playground. I walked a mile over a hill to Eagle Rock High School where I had my first brush with geometry, algebra, physics, and electric shop. I had some fine teachers. Ben Culley, one of my math teachers, went on to be dean of men at Occidental College. We had a radio at home and that intrigued me. I pestered the local radio repair shop and was allowed to help out by testing tubes. We had no automobile but I made the effort to bicycle to the Friday night lectures at Caltech. I saw the 100‐inch Mount Wilson telescope lens when it was moved out of the optics lab. I saw the demonstration at the Kellogg high voltage lab. In my teen years I was leaning toward things electrical. Then Pearl Harbor was bombed. I remember Roosevelt’s famous infamy radio speech. In 3 weeks I turned 17. I remember the air raid sirens and the blackouts. I remember when the Japanese shelled the west coast and the searchlights came on. I remember gas masks were issued and there was gas and food rationing. Members of my class were volunteering into the services and big changes were taking place in the lives around me.

I was drafted into the army in the April of 1943 and did basic training in Fresno, California. The army sent me to Oregon State College as part of an Army Specialized Training Program. I had my first bus and train ride. At OSC I had a few basic engineering courses. Much of the class material was a review for me. It was decided that the war was not going to last decades and the education of future engineers was not a high priority. My start in college lasted about 6 months and I was shipped off to the 89th infantry division at Hunter Liggett Military Reservation in California. I was given a course in radio repair at Fort Benning, Georgia. The division eventually ended up crossing Germany in Patton’s third army. I saw bombed out cities. I watched and heard the bombing during the Rhine river crossing. I did my calculus through the University of California correspondence course in this period. I remember working problems when one of our own aircrafts was shot down because he was firing on us. The army went as far as Zwickau and I saw the exodus of slave labor. They were walking back to their