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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
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.
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Veröffentlichungsjahr: 2017
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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.
Guide
Cover
Table of Contents
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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–dc23LC record available at https://lccn.loc.gov/2017037713
Cover Design: WileyCover 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 home cities with no food or belongings. Our division uncovered one of the concentration camps. This was the first knowledge I had of what had been going on in Europe in the preceding years. It was hard to grasp.
After hostilities, it took months before we could return home. The war was still in progress in the Pacific. This meant that there were only so many ships available. I visited London, Brussels, Edinburgh, and Glasgow on passes. I saw the Loch Ness. Since I was a violinist, I took the opportunity to join a GI symphony orchestra. I spent a month in Paris before we were moved to Frankfurt. It was a big transition—from army life in war to a home in a French mansion. The orchestra toured Germany and Austria entertaining troops. I saw a lot of Europe including the war crimes trial at Nuremburg and the inside of Hitler’s bunker in Berlin. We played in the Schonbrunn Palace in Vienna, in the Wagner Festspiel Haus in Beirut, and in Garmisch Partenkirchen. For a kid that had never left home, I had quite an adventure in the army.
Three years in the service and I finally returned home. I wanted to use the GI bill to get a college degree at Caltech. I was 21 years old. The first thing I did personally was add a room to our home so that I had a place to study. The backlog of students trying to continue their education was long and my only option was to take the junior entrance exam. I was given credit for my classes at Oregon State and my correspondence course. I studied all summer so that I could take exams in English, math, chemistry, and physics. I was one of six that was accepted. I chose physics as my major as I really did not know what direction to take. I finished my senior year without enough credits to graduate. I came back for two more terms and nearly finished all the courses needed to get a Masters in EE. I had used up my GI bill. I had a difficult time starting as a junior but somehow I made it. I graduated with the class of 1949. I still remember that my first physics course was given by Dr. Carl Anderson, the Nobel prize winner that discovered the positron. I was in a different world. I had no more funds and I had to go to work.
My first job was with a company called Applied Physics Corporation in Pasadena, CA. I worked for George W. Downs, a respected technical consultant with ties to Caltech, the US Navy, and the Atomic Energy Commission. My first assignment was to build a dc amplifier for Douglas Aircraft. In 1950, there were only vacuum tubes for gain. I was shown a circuit that used a mechanical chopper to stabilize a feedback amplifier. Vacuum tubes require hundreds of volts to operate and there had to be transformers to isolate the circuits from utility ground. My first dc amplifier and power supply weighed over 70 pounds. Looking back, it is hard to believe that this was progress. Based on what had been learned, my next dc amplifiers were much smaller and a group of amplifiers shared one power supply. These early designs were bought by the aircraft companies to handle the signals from strain gauges and thermocouples. These were the days when the first jet aircraft was still on the drawing board. I was given the job of building four analog computers that paralleled work done at Caltech. Each of these computers filled a room and used the dc amplifier designs I had worked on. These computers were sold to Lockheed, Douglas, and North American Aircraft.
Digital computing was in its infancy. When my first boss was asked whether analog or digital computing was best, he responded—“Get them both. You need all the help you can get.” If I were asked whether field theory or circuit theory is best I would have to answer a little differently. You need to use them both. One alone is not sufficient.
Our group of designers were moved to Transformer Engineers, another Pasadena company. I invented a way to build dc amplifiers and avoid voltage regulation using two blocks of ac gain, feedback, and a mechanical chopper to reduce the size of a channel but management did not want to enter this market. Four of us including George, left and formed our own company called Dynamics Instrumentation. The new design was a viable product and within a year I had invented a reasonably good differential amplifier that provided a bandwidth of 10 kHz. I began to understand that each amplifier channel needed its own power supply or there would be system oscillations. Following soon were the days of the first transistors and the instruments were getting smaller and more sophisticated. This was the period when rocket engines were being tested for space exploration. As semiconductors developed I was eventually able to build differential amplifiers without mechanical choppers that were extremely stable.
I began to write small articles that were used as sales tools. There was essentially no written material available for engineers to study and these articles were very effective sales tools. These articles about shields, the shielding of instruments and the grounding of cable shields, led me to write my first book. Much to my surprise Wiley accepted my manuscript for publication. What I did not know was that the engineers buying the instrumentation had little to say about how the facility would handle the cables and their terminations.
Of course, grounding and shielding involves far more than testing aircraft or rockets. It involves electronics in medicine, research, manufacturing, and computers. Instruments had to function in adverse environments and survive when there was nearby lightning activity. I learned how to protect input circuits from significant overloads. Input noise levels of 2 microvolts rms in 100 kHz were accepted standards and yet the instruments were protected even if the power line were connected to the input. Instruments could operate with 300 volts ground potential differences between input and output.
As a principal in my own company I had the opportunity to visit and talk to engineers in facilities all over the United States. They were very willing to show me their testing installations and rooms full of electronics. A typical rack would be opened up and all I could see was a bundle of cables a foot in diameter coming out of the floor and fanning out to hardware. It was impressive and I had no idea of what this meant from the standpoint of performance. All I knew was that if I tested an instrument on my bench it would meet my published specifications. All of this contact gave me an understanding of electronics which I did not get in college.
Dynamics came to an abrupt halt as a company in one of the big cutbacks in defense spending. I went to work for a company that supplied equipment to the telephone industry. I remember being shown the special earth ground that had been brought up into the lab. This was apparently standard practice in the telephone industry. The chief engineer felt strongly that this connection would ensure that electronics could be tested in a “quiet” environment because this ground was available. I did not respond because all of my experience indicated that this ground was of little importance. To me it was just another earthed conductor along with water pipes, gas lines, and electrical conduit. The only difference was they each had a special title.
The telephone system in those days rang bells by placing a voltage between one telephone line and earth. The telephone systems would work even though there was a power outage as the system ran on batteries where the positive lead was grounded. The ground conductor I was shown was a part of telephone practice. I later became chief engineer of that company and never once did I use that special ground.
I understood the philosophy of grounding analog amplifiers. I had built analog circuits and found that “hum” pickup was reduced if I grounded my circuits to a nearby conduit. My approach in instrumentation had been that if I had to use special grounds to get performance, my design was inadequate. What I was learning was that this search for “good ground” had caught on and was accepted as good engineering. I found the idea that a good ground would work for a facility regardless of its size ridiculous. But as I traveled the country I found this idea had taken hold and was accepted as good practice.
As an April fool’s joke I submitted a news article to an electronics magazine describing that the perfect ground had been discovered near Nome Alaska and it was being protected against contamination by a fence.
I had occasion to visit a deep space antenna facility in the Mohave desert. There was a circle of buildings with a central point acting as ground for all the electronics. This ground was made from buried copper rod. The power for each building was supplied through a nearby distribution transformer that was grounded (earthed) at the transformer per the electrical code. The problem occurred during thunder storm activity. Lightning would strike the earth causing a potential difference between the central ground and the utility ground at each building. A nearby lightning strike would place thousands of volts across the coils of the distribution transformer. The result was that these transformers were being blown up. This grounding practice was written into law and quality control would not accept any change to this practice. What bothered me the most was that the engineers we talked to had no idea of what was wrong. They were interested in the performance of individual pieces of hardware and the facility issues were not their domain.
This single‐point grounding practice was what I saw in most major defense installations. All the shields for all the signals were bundled together and connected to this “good” ground. The simple physics in my book showed why this could not work, but no one paid attention to what I considered to be obvious. Buildings are not circuits and the single point grounds that worked in many applications could not function in these large environments. They thought they knew where the interfering current entered the sink but no one asked where the current came back out of the earth. The idea of skin effect was never considered.
The first electronic instruments I designed were full of shielded conductors. This is labor intensive and adds a lot of bulk and cost to a design. My last designs used no shielded conductors. In feedback structures, most of the interference is cancelled. Knowing how to route signals and how to control impedance levels, use differential techniques made for simple layouts. In the end, there were no calculations—just technique and it worked.
Making things work well and at the same time keeping things simple is a challenge. There are only so many coupling mechanisms. Understanding that both interference and signals obey the same laws is key to finding answers. When I viewed a facility problem my circuit experience served me well. I could see the problem in terms of the spaces not the conductors. The rules people usually follow involve conductors without regard to the geometry. For example, the service entrance to a residence requires a grounding conductor. The intent is to provide a path for lightning to earth. If the conductor is routed around a door or along a wall for any distance to get to a water pipe, it will not function even though it passes inspection. People follow rules. They have no choice.
I visited a facility in New Mexico that assembled live missiles for the air force. The fear was that an ESD event might arm a missile. I was called in because a missile had somehow been armed. Every worker at a bench wore a conducting wrist band that was connected to his or her bench and seat. The floors were conductive and the walls of the building were corrugated steel. This facility was located in an area where lightning frequency is high. When I arrived, there was a group of inspectors in white smocks and with clipboards touring the facility looking for any rule violations. I was told that if there was a chance of lightning, the building would be evacuated.
I noticed that the building had lightning arrestors on the roof eaves and that there were down‐conductors from these arrestors to grounding posts. Then I saw a television antenna that was taller than the lightning protection. What I saw next was that lightning would use the corrugated steel walls as a down conductor, not the down‐conductors provided. The problem then was that lightning using this path would arc to earth at floor level. Missiles were located on the other side of the wall just feets from the points of possible arcing. I recommended that the building steel be grounded at points around the perimeter of the building. Any arcing at this level could easily arm a missile. The lesson here is that following written rules does not always solve problems. Common sense is important.
My music provided another side to my life that was unusual. I play chamber music and this has brought me in touch with some very interesting people. In Pasadena, I played music with Rupert Pole who was married to Anais Nin, the famous diarist. I played music with Alice Leighton, wife of Robert Leighton, who helped write the famous Physics Lecture Series with Dr. Feynman. Stuart Canin, who became concertmaster of the San Francisco Symphony was concertmaster of the GI Symphony and played for Roosevelt, Churchill, and Stalin in Potsdam during our stay in Berlin. At the time, this was done in secret.
I had a similar experience when the GI orchestra was stationed in Frankfurt. I played quartets (background music) for a group of officers holding a fancy dinner party at a castle on the banks of the Rhine river. They were living it up with a group of army nurses. I would have never seen the inside of a castle if it were not for music.
My first book was published by John Wiley and Sons in 1967. This was a period in time when rocket engines were being developed. The title of this book was Grounding and Shielding in Instrumentation. The main problem I addressed was related to limiting interference to microvolts when the input signal lines ran thousands of feet between rocket stands and instrumentation bunkers. Designing instrumentation amplifiers using vacuum tubes that worked in this environment meant I had to understand interference from both internal and external sources. I had solved the instrumentation problems but the users had to understand their role in handling long input cables. It is a long story but in later years I found out that my recommendations were largely ignored. Performance was impacted but obviously systems worked well enough to get men on the moon. I have rewritten Grounding and Shielding every 10 years and the 6th edition just came out in 2016. I have no doubt that many of the shielding issues that I discuss in my books are still not being handled correctly. What often happens is that as new technology enters the scene the old problems simply fade away. It is not comforting to realize that progress often takes this form. A lack of understanding persists and it will cause problems in some future effort. We seldom argue with a practice if it works. I do not like invalid arguments that supported bad practice. It leads to problems in the future.
I found it very rewarding to put my understanding into the written word. Writing it down on paper forces me to be accurate. My understanding in many areas was challenged and I had many things to learn. My first book brought me consulting jobs as well as opportunities to teach seminars. The more contact I had with engineers the more convinced I became that they were not using the physics they had been taught in school. It was through my books that Dan Beeker found me and asked me to do a few seminars for his company.
These early seminars were not directed at the world of circuit boards. They covered areas of power distribution, radiation, and instrumentation. The subjects of grounding and shielding were treated for both analog and rf circuits. Facility design, lightning protection, ESD, screen room design, and radiation from antennas were all key topics. My talks had one thing in common: the problems of interference were all field related. For Dan’s audience, I began to include topics related to transmission lines on circuit boards. Dan heard my talk dozens of times. I contradicted many of his pet ideas. I told a story that was different than other speakers. Much to his credit he began to see a light and he began changing his approach to board layout. He has become very successful at trouble shooting problems using a new set of ideas. His boards work the first time.
