Electromagnetic Compatibility Engineering

Preface xxiii

Part 1 EMC Theory 1

1 Electromagnetic Compatibility 3

1.1 Introduction 3

1.2 Noise and Interference 3

1.3 Designing for Electromagnetic Compatibility 4

1.4 Engineering Documentation and EMC 6

1.5 United States’ EMC Regulations 6

1.6 Canadian EMC Requirements 19

1.7 European Union’s EMC Requirements 20

1.8 International Harmonization 26

1.9 Military Standards 27

1.10 Avionics 28

1.11 The Regulatory Process 30

1.12 Typical Noise Path 30

1.14 Miscellaneous Noise Sources 33

1.15 Use of Network Theory 36

Summary 38

Problems 39

References 41

Further Reading 42

2 Cabling 44

2.1 Capacitive Coupling 45

2.2 Effect of Shield on Capacitive Coupling 48

2.3 Inductive Coupling 52

2.4 Mutual Inductance Calculations 54

2.5 Effect of Shield on Magnetic Coupling 56

2.6 Shielding to Prevent Magnetic Radiation 64

2.7 Shielding a Receptor Against Magnetic Fields 67

2.8 Common Impedance Shield Coupling 69

2.9 Experimental Data 70

2.10 Example of Selective Shielding 74

2.11 Shield Transfer Impedance 75

2.12 Coaxial Cable Versus Twisted Pair 75

2.13 Braided Shields 79

2.14 Spiral Shields 81

2.15 Shield Terminations 84

2.16 Ribbon Cables 94

2.17 Electrically Long Cables 96

Summary 96

Problems 98

References 103

Further Reading 104

3 Grounding 106

3.1 AC Power Distribution and Safety Grounds 107

3.2 Signal Grounds 120

3.3 Equipment/System Grounding 132

3.4 Ground Loops 142

3.5 Low-Frequency Analysis of Common-Mode Choke 147

3.6 High-Frequency Analysis of Common-Mode Choke 152

3.7 Single Ground Reference for a Circuit 154

Summary 155

Problems 156

References 157

Further Reading 157

4 Balancing and Filtering 158

4.1 Balancing 158

4.2 Filtering 174

4.3 Power Supply Decoupling 178

4.4 Driving Capacitive Loads 186

4.5 System Bandwidth 188

4.6 Modulation and Coding 190

Summary 190

Problems 191

References 192

Further Reading 193

5 Passive Components 194

5.1 Capacitors 194

5.2 Inductors 203

5.3 Transformers 204

5.4 Resistors 206

5.5 Conductors 208

5.6 Transmission Lines 215

5.7 Ferrites 225

Summary 233

Problems 234

References 237

Further Reading 237

6 Shielding 238

6.1 Near Fields and Far Fields 238

6.2 Characteristic and Wave Impedances 241

6.3 Shielding Effectiveness 243

6.4 Absorption Loss 245

6.5 Reflection Loss 249

6.6 Composite Absorption and Reflection Loss 257

6.7 Summary of Shielding Equations 260

6.8 Shielding with Magnetic Materials 260

6.9 Experimental Data 265

6.10 Apertures 267

6.11 Waveguide Below Cutoff 280

6.12 Conductive Gaskets 282

6.13 The ‘‘IDEAL’’ Shield 287

6.14 Conductive Windows 288

6.16 Internal Shields 293

6.17 Cavity Resonance 295

6.18 Grounding of Shields 296

Summary 296

Problems 297

References 299

Further Reading 300

7 Contact Protection 302

7.1 Glow Discharges 302

7.2 Metal-Vapor or Arc Discharges 303

7.3 AC Versus DC Circuits 305

7.4 Contact Material 306

7.5 Contact Rating 306

7.6 Loads with High Inrush Currents 307

7.7 Inductive Loads 308

7.8 Contact Protection Fundamentals 310

7.9 Transient Suppression for Inductive Loads 314

7.10 Contact Protection Networks for Inductive Loads 318

7.11 Inductive Loads Controlled by a Transistor Switch 322

7.12 Resistive Load Contact Protection 323

7.13 Contact Protection Selection Guide 323

7.14 Examples 324

Summary 325

Problems 326

References 327

Further Reading 327

8 Intrinsic Noise Sources 328

8.1 Thermal Noise 328

8.2 Characteristics of Thermal Noise 332

8.3 Equivalent Noise Bandwidth 334

8.4 Shot Noise 337

8.5 Contact Noise 338

8.6 Popcorn Noise 339

8.7 Addition of Noise Voltages 340

8.8 Measuring Random Noise 341

Summary 342

Problems 343

References 345

Further Reading 345

9 Active Device Noise 346

9.1 Noise Factor 346

9.2 Measurement of Noise Factor 349

9.3 Calculating S/N Ratio and Input Noise Voltage from Noise Factor 351

9.4 Noise Voltage and Current Model 353

9.5 Measurment of Vn and In 355

9.6 Calculating Noise Factor and S/N Ratio from Vn–In 356

9.7 Optimum Source Resistance 357

9.8 Noise Factor of Cascaded Stages 360

9.9 Noise Temperature 362

9.10 Bipolar Transistor Noise 364

9.11 Field-Effect Transistor Noise 368

9.12 Noise in Operational Amplifiers 370

Summary 375

Problems 376

References 377

Further Reading 378

10 Digital Circuit Grounding 379

10.1 Frequency Versus Time Domain 380

10.2 Analog Versus Digital Circuits 380

10.3 Digital Logic Noise 380

10.4 Internal Noise Sources 381

10.5 Digital Circuit Ground Noise 384

10.6 Ground Plane Current Distribution and Impedance 391

10.7 Digital Logic Current Flow 412

Summary 419

Problems 420

References 421

Further Reading 422

Part 2 EMC Applications 423

11 Digital Circuit Power Distribution 425

11.1 Power Supply Decoupling 425

11.2 Transient Power Supply Currents 426

11.3 Decoupling Capacitors 431

11.4 Effective Decoupling Strategies 436

11.5 The Effect of Decoupling on Radiated Emissions 454

11.6 Decoupling Capacitor Type and Value 456

11.7 Decoupling Capacitor Placement and Mounting 457

11.8 Bulk Decoupling Capacitors 459

11.9 Power Entry Filters 460

Summary 461

Problems 461

References 463

Further Reading 463

12 Digital Circuit Radiation 464

12.1 Differential-Mode Radiation 465

12.2 Controlling Differential-Mode Radiation 471

12.3 Common-Mode Radiation 477

12.4 Controlling Common-Mode Radiation 480

Summary 488

Problems 489

References 490

Further Reading 491

13 Conducted Emissions 492

13.1 Power Line Impedance 492

13.2 Switched-Mode Power Supplies 495

13.3 Power-Line Filters 511

13.4 Primary-to-Secondary Common-Mode Coupling 523

13.5 Frequency Dithering 524

13.6 Power Supply Instability 524

13.7 Magnetic Field Emissions 525

13.8 Variable Speed Motor Drives 528

13.9 Harmonic Suppression 536

Summary 541

Problems 542

References 544

Further Reading 544

14 RF and Transient Immunity 545

14.1 Performance Criteria 545

14.2 RF Immunity 546

14.3 Transient Immunity 557

14.4 Power Line Disturbances 572

Summary 575

Problems 576

References 578

Further Reading 579

15 Electrostatic Discharge 580

15.1 Static Generation 580

15.2 Human Body Model 587

15.3 Static Discharge 589

15.4 ESD Protection in Equipment Design 592

15.5 Preventing ESD Entry 594

15.6 Hardening Sensitive Circuits 608

15.7 ESD Grounding 608

15.8 Nongrounded Products 609

15.9 Field-Induced Upset 610

15.10 Transient Hardened Software Design 612

15.11 Time Windows 617

Summary 617

Problems 619

References 620

Further Reading 621

16 PCB Layout and Stackup 622

16.1 General PCB Layout Considerations 622

16.2 PCB-to-Chassis Ground Connection 625

16.3 Return Path Discontinuities 626

16.4 PCB Layer Stackup 635

Summary 655

Problems 657

References 658

Further Reading 658

17 Mixed-Signal PCB Layout 660

17.1 Split Ground Planes 660

17.2 Microstrip Ground Plane Current Distribution 662

17.3 Analog and Digital Ground Pins 665

17.4 When Should Split Ground Planes Be Used? 668

17.5 Mixed Signal ICs 669

17.6 High-Resolution A/D and D/A Converters 671

17.7 A/D and D/A Converter Support Circuitry 676

17.8 Vertical Isolation 679

17.9 Mixed-Signal Power Distribution 681

17.10 The IPC Problem 684

Summary 685

Problems 686

References 687

Further Reading 687

18 Precompliance EMC Measurements 688

18.1 Test Environment 689

18.2 Antennas Versus Probes 689

18.3 Common-Mode Currents on Cables 690

18.4 Near Field Measurements 694

18.5 Noise Voltage Measurements 697

18.6 Conducted Emission Testing 700

18.7 Spectrum Analyzers 707

18.8 EMC Crash Cart 711

18.9 One-Meter Radiated Emission Measurements 713

18.10 Precompliance Immunity Testing 717

18.11 Precompliance Power Quality Tests 723

18.12 Margin 726

Summary 728

Problems 729

References 730

Further Reading 731

Appendix 733

A. The Decibel 733

B. The Ten Best Ways to Maximize the Emission from Your Product 740

C. Multiple Reflections of Magnetic Fields in Thin Shields 743

D. Dipoles for Dummies 746

E. Partial Inductance 765

F. Answers to Problems 790

Index 825