9780130669469

This thorough review of the fundamental principles associated with signal integrity provides engineering principles behind signal integrity effects, and applies this understanding to solving problems.

Preface

xiii

Signal Integrity Is in Your Future

1

(40)

What Is Signal Integrity?

2

(3)

Signal Quality on a Single Net

5

(3)

Cross Talk

8

(2)

Rail-Collapse Noise

10

(3)

Electromagnetic Interference (EMI)

13

(2)

Two Important Signal Integrity Generalizations

15

(1)

Trends in Electronic Products

16

(5)

The Need for a New Design Methodology

21

(1)

A New Product Design Methodology

22

(1)

Simulations

23

(4)

Modeling and Models

27

(2)

Creating Circuit Models from Calculation

29

(5)

Three Types of Measurements

34

(3)

The Role of Measurements

37

(2)

The Bottom Line

39

(2)

Time and Frequency Domains

41

(38)

The Time Domain

42

(2)

Sine Waves in the Frequency Domain

44

(2)

Shorter Time to a Solution in the Frequency Domain

46

(1)

Sine Wave Features

47

(2)

The Fourier Transform

49

(2)

The Spectrum of a Repetitive Signal

51

(2)

The Spectrum of an Ideal Square Wave

53

(2)

From the Frequency Domain to the Time Domain

55

(1)

Effect of Bandwidth on Rise Time

56

(3)

Bandwidth and Rise Time

59

(2)

What Does ``Significant'' Mean?

61

(3)

Bandwidth of Real Signals

64

(2)

Bandwidth and Clock Frequency

66

(2)

Bandwidth of a Measurement

68

(2)

Bandwidth of a Model

70

(1)

Bandwidth of an Interconnect

71

(5)

The Bottom Line

76

(3)

Impedance and Electrical Models

79

(30)

Describing Signal-Integrity Solutions in Terms of Impedance

80

(2)

What Is Impedance?

82

(2)

Real vs. Ideal Circuit Elements

84

(2)

Impedance of an Ideal Resistor in the Time Domain

86

(1)

Impedance of an Ideal Capacitor in the Time Domain

87

(3)

Impedance of an Ideal Inductor in the Time Domain

90

(2)

Impedance in the Frequency Domain

92

(5)

Equivalent Electrical Circuit Models

97

(2)

Circuit Theory and SPICE

99

(4)

Introduction to Modeling

103

(5)

The Bottom Line

108

(1)

The Physical Basis of Resistance

109

(14)

Translating Physical Design into Electrical Performance

110

(1)

The Only Good Approximation for the Resistance of Interconnects

111

(3)

Bulk Resistivity

114

(1)

Resistance per Length

115

(2)

Sheet Resistance

117

(4)

The Bottom Line

121

(2)

The Physical Basis of Capacitance

123

(24)

Current Flow in Capacitors

124

(2)

The Capacitance of a Sphere

126

(1)

Parallel Plate Approximation

127

(2)

Dielectric Constant

129

(1)

Power and Ground Planes and Decoupling Capacitance

130

(4)

Capacitance per Length

134

(5)

2D Field Solvers

139

(3)

Effective Dielectric Constant

142

(4)

The Bottom Line

146

(1)

The Physical Basis of Inductance

147

(58)

What Is Inductance?

147

(1)

Inductance Principle #1: There Are Circular Magnetic-Field Line Loops Around All Currents

148

(2)

Inductance Principle #2: Inductance Is the Number of Webers of Field Line Loops Around a Conductor per Amp of Current Through It

150

(2)

Self-Inductance and Mutual Inductance

152

(2)

Inductance Principle #3: When the Number of Field Line Loops Around a Conductor Changes, There Will Be a Voltage Induced Across the Ends of the Conductor

154

(3)

Partial Inductance

157

(6)

Effective, Total, or Net Inductance and Ground Bounce

163

(6)

Loop Self- and Mutual Inductance

169

(5)

The Power-Distribution System (PDS) and Loop Inductance

174

(5)

Loop Inductance per Square of Planes

179

(2)

Loop Inductance of Planes and Via Contacts

181

(2)

Loop Inductance of Planes with a Field of Clearance Holes

183

(2)

Loop Mutual Inductance

185

(1)

Equivalent Inductance

185

(2)

Summary of Inductance

187

(2)

Current Distributions and Skin Depth

189

(9)

High-Permeability Materials

198

(2)

Eddy Currents

200

(2)

The Bottom Line

202

(3)

The Physical Basis of Transmission Lines

205

(72)

Forget the Word Ground

206

(1)

The Signal

207

(1)

Uniform Transmission Lines

208

(2)

The Speed of Electrons in Copper

210

(1)

The Speed of a Signal in a Transmission Line

211

(4)

Spatial Extent of the Leading Edge

215

(1)

``Be the Signal''

216

(4)

The Instantaneous Impedance of a Transmission Line

220

(3)

Characteristic Impedance and Controlled Impedance

223

(2)

Famous Characteristic Impedances

225

(3)

The Impedance of a Transmission Line

228

(5)

Driving a Transmission Line

233

(3)

Return Paths

236

(4)

When Return Paths Switch Reference Planes

240

(12)

A First-Order Model of a Transmission Line

252

(5)

Calculating Characteristic Impedance with Approximations

257

(4)

Calculating the Characteristic Impedance with a 2D Field Solver

261

(5)

An n-Section Lumped Circuit Model

266

(7)

Frequency Variation of the Characteristic Impedance

273

(2)

The Bottom Line

275

(2)

Transmission Lines and Reflections

277

(56)

Reflections at Impedance Changes

278

(2)

Why Are There Reflections?

280

(3)

Reflections from Resistive Loads

283

(3)

Source Impedance

286

(2)

Bounce Diagrams

288

(1)

Simulating Reflected Waveforms

289

(3)

Measuring Reflections with a TDR

292

(3)

Transmission Lines and Unintentional Discontinuities

295

(2)

When to Terminate

297

(3)

The Most Common Termination Strategy for Point-to-Point Topology

300

(2)

Reflections from Short Series Transmission Lines

302

(3)

Reflections from Short-Stub Transmission Lines

305

(2)

Reflections from Capacitive End Terminations

307

(3)

Reflections from Capacitive Loads in the Middle of a Trace

310

(3)

Capacitive Delay Adders

313

(2)

Effects of Corners and Vias

315

(5)

Loaded Lines

320

(3)

Reflections from Inductive Discontinuities

323

(5)

Compensation

328

(2)

The Bottom Line

330

(3)

Lossy Lines, Rise-Time Degradation, and Material Properties

333

(68)

Why Worry About Lossy Lines

334

(2)

Losses in Transmission Lines

336

(2)

Sources of Loss: Conductor Resistance and Skin Depth

338

(4)

Sources of Loss: The Dielectric

342

(5)

Dissipation Factor

347

(3)

The Real Meaning of Dissipation Factor

350

(5)

Modeling Lossy Transmission Lines

355

(8)

Characteristic Impedance of a Lossy Transmission Line

363

(2)

Signal Velocity in a Lossy Transmission Line

365

(2)

Attenuation and the dB

367

(5)

Attenuation in Lossy Lines

372

(9)

Measured Properties of a Lossy Line in the Frequency Domain

381

(5)

The Bandwidth of an Interconnect

386

(6)

Time-Domain Behavior of Lossy Lines

392

(4)

Improving the Eye Diagram of a Transmission Line

396

(2)

Pre-emphasis and Equalization

398

(1)

The Bottom Line

399

(2)

Cross Talk in Transmission Lines

401

(70)

Superposition

402

(1)

Origin of Coupling: Capacitance and Inductance

403

(2)

Cross Talk in Transmission Lines: NEXT and FEXT

405

(2)

Describing Cross Talk

407

(2)

The SPICE Capacitance Matrix

409

(4)

The Maxwell Capacitance Matrix and 2D Field Solvers

413

(6)

The Inductance Matrix

419

(2)

Cross Talk in Uniform Transmission Lines and Saturation Length

421

(5)

Capacitively Coupled Currents

426

(4)

Inductively Coupled Currents

430

(3)

Near-End Cross Talk

433

(3)

Far-End Cross Talk

436

(7)

Decreasing Far-End Cross Talk

443

(2)

Simulating Cross Talk

445

(7)

Guard Traces

452

(7)

Cross Talk and Dielectric Constant

459

(1)

Cross Talk and Timing

460

(4)

Switching Noise

464

(4)

Summary of Reducing Cross Talk

468

(1)

The Bottom Line

468

(3)

Differential Pairs and Differential Impedance

471

(80)

Differential Signaling

472

(4)

A Differential Pair

476

(2)

Differential Impedance with No Coupling

478

(4)

The Impact from Coupling

482

(6)

Calculating Differential Impedance

488

(4)

The Return-Current Distribution in a Differential Pair

492

(6)

Odd and Even Modes

498

(5)

Differential Impedance and Odd-Mode Impedance

503

(1)

Common Impedance and Even-Mode Impedance

504

(3)

Differential and Common Signals and Odd- and Even-Mode Voltage Components

507

(2)

Velocity of Each Mode and Far-End Cross Talk

509

(6)

Ideal Coupled Transmission-Line Model or an Ideal Differential Pair

515

(1)

Measuring Even- and Odd-Mode Impedance

516

(2)

Terminating Differential and Common Signals

518

(7)

Conversion of Differential to Common Signals

525

(5)

EMI and Common Signals

530

(5)

Cross Talk in Differential Pairs

535

(2)

Crossing a Gap in the Return Path

537

(3)

To Tightly Couple or Not to Tightly Couple

540

(2)

Calculating Odd and Even Modes from Capacitance- and Inductance-Matrix Elements

542

(4)

The Characteristic Impedance Matrix

546

(3)

The Bottom Line

549

(2)

Appendix A

551

(8)

Appendix B

559

(12)

Appendix C

571

(2)

Index

573

(14)

About the Author

587

What is included with this book?

The New copy of this book will include any supplemental materials advertised. Please check the title of the book to determine if it should include any access cards, study guides, lab manuals, CDs, etc.

The Used, Rental and eBook copies of this book are not guaranteed to include any supplemental materials. Typically, only the book itself is included. This is true even if the title states it includes any access cards, study guides, lab manuals, CDs, etc.

PrefacePrinted circuit-board and IC-package design used to be a field that involved expertise in layout, CAD, logic design, heat transfer, mechanical engineering, and reliability analysis. With modern digital electronic systems pushing beyond the 1-GHz barrier, packaging and board designers must now balance signal integrity and electrical performance with these other concerns.Everyone who touches the physical design of a product has the potential of affecting the performance. All designers should understand how what they do will affect signal integrity or, at the very least, be able to talk with engineers who are responsible for the signal integrity.The old design methodology of building prototypes, hoping they work, and then testing them to find out is no longer cost effective when time to market is as important as cost and performance. If signal integrity is not taken into account from the beginning, there is little hope a design will work the first time.In our new "high-speed" world, where the packaging and interconnect are no longer electrically transparent to the signals, a new methodology for designing a product right the first time is needed. This new methodology is based on predictability. The first step is to use established design guidelines based on engineering discipline. The second step is to evaluate the expected performance by "putting in the numbers." This is what distinguishes engineering from guesswork. It takes advantage of four important tools: rules of thumb, analytic approximations, numerical simulation tools, and measurements. With an efficient design and simulation process, many of the trade-offs between the expected performance and the ultimate cost can be evaluated early in the design cycle, where the time, risk, and cost savings will have the biggest impact. The way to solve signal integrity problems is to first understand their origin and then apply all the tools in our toolbox to find and verify the optimum solution.The design process is an intuitive one. The source of inspiration for a new way of solving a problem is that mysterious world of imagination and creativity. An idea is generated and the analytical powers of our technical training take over to massage the idea into a practical solution. Though computer simulations are absolutely necessary for final verification of a solution, they only rarely aid in our intuitive understanding. Rather, it is an understanding of the mechanisms, principles and definitions, and exposure to the possibilities, that contribute to the creation of a solution. Arriving at that initial guess and knowing the places to look for solutions require understanding and imagination.This book emphasizes the intuitive approach. It offers a framework for understanding the electrical properties of interconnects and materials that apply across the entire hierarchy from on-chip, through the packages, circuit boards, connectors, and cables.Those struggling with the confusing and sometimes contradictory statements made in the trade press will use this book as their starting place. Those experienced in electrical design will use this book as the place to finally understand what the equations mean.In this book, terms are introduced starting at the ground floor. For example, the impedance of a transmission line is the most fundamental electrical property of an interconnect. It describes what a signal will see electrically and how it will interact with the interconnects. For those new to signal integrity, most of the problems arise from confusion over three terms: the characteristic impedance, the impedance, and the instantaneous impedance a signal sees. This distinction is even important for experienced engineers. This book introduces the reader to each of these terms and their meanings, without complex mathematics.New topics are introduced at a basic level; most are not covered in other signal integrity books

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Signal Integrity - Simplified

Signal Integrity - Simplified

0130669466

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