Grounds for Grounding: A Circuit-to-System Handbook

GROUNDS FOR GROUNDING......Page 4
CONTENTS......Page 10
Foreword......Page 20
Preface......Page 22
1. Overview......Page 26
Bibliography......Page 31
2.1. Maxwell’s Equations Demystified......Page 32
2.1.1. Fundamental Terms......Page 34
2.1.2. Maxwell’s Equations......Page 37
2.2. Boundary Conditions......Page 49
2.3. Intrinsic Inductance of Conductors and Interconnects......Page 51
2.3.2. Self-Inductance......Page 52
2.3.3. Mutual Inductance......Page 54
2.3.4. Partial Inductance......Page 55
2.3.5. External and Internal Inductance......Page 62
2.3.6. Skin Effect and Skin Depth......Page 63
2.3.7. Proximity Effect......Page 68
2.4. Nonideal Properties of Passive Circuit Components and Interconnects......Page 70
2.4.1. Resistors......Page 71
2.4.2. Capacitors......Page 72
2.4.4. Interconnects (Wires and PCB Traces)......Page 74
2.5.1. What Path Should Return Currents Follow?......Page 76
2.5.2. Equivalent Circuit Analysis......Page 78
2.6. Transmission Line Fundamentals......Page 89
2.6.1. Transmission Line Definition......Page 90
2.6.2. Transmission Line Equations and Intrinsic Parameters......Page 91
2.6.3. Transmission Line Termination and Loading Conditions......Page 94
2.7. Characteristics of Signals and Circuits......Page 99
2.7.1. Spectral Content of Signals......Page 100
2.7.2. Differential-Mode and Common-Mode Signals......Page 106
2.7.3. Common-Mode (CM) to Differential-Mode (DM) Conversion......Page 116
2.7.4. Differential Signaling and Balanced Circuits......Page 120
2.8.1. Radiation from Current-Carrying Conductors......Page 129
2.8.2. Flux Cancellation, the Electromagnetics of Balancing......Page 133
Bibliography......Page 135
3.1.1. “Grounding,” One Term, Many Imports......Page 138
3.1.2. Grounding—A Historical Perspective and the Evolution of the Term......Page 143
3.1.3. Grounding-Related Myths, Misconceptions, and Misapprehensions......Page 145
3.2. Objectives of Grounding......Page 148
3.2.1. Safety Grounding......Page 151
3.2.2. Grounding for Control of Electromagnetic Interference (EMI)......Page 163
3.2.3. Signal Grounding......Page 166
3.3.1. Case #1: The Grounds for Electrostatic Discharge (ESD)......Page 173
3.3.2. Case #2: The Grounds for Lightning Protection......Page 174
Bibliography......Page 178
4.1.1. Grounding May Not be the Solution; Rather it Could be Part of the Problem......Page 180
4.1.2. Controlling Common-Impedance Interference Coupling......Page 186
4.2.1. The Need for Different Topologies......Page 198
4.2.2. Grounding Topologies......Page 201
4.3.1. Objectives and Basic Design Considerations......Page 234
4.3.2. Ground Tree Design Methodology......Page 235
4.4. Role of Switch-Mode Power Supplies in Grounding System Design......Page 249
4.4.1. Principle of Switch-Mode Power Supply Operation......Page 250
4.4.2. The Need for Isolation......Page 251
4.4.3. Isolation and Grounding in Switch-Mode Power Supplies......Page 254
4.5. Ground Loops......Page 258
4.5.1. Definition of a “Ground Loop”......Page 259
4.5.2. Ground Loop Consequences (“Who’s Afraid of the Big Bad Loop?”)......Page 264
4.5.3. Ground-Loop Interference Coupling......Page 266
4.5.4. Ground-Loop Interactions: Frequency Considerations in CM-to-DM Interference Conversion......Page 282
4.5.5. Resolving Ground-Loop Problems......Page 289
4.6.1. The Zoning Concept as Applied to Grounding......Page 316
4.6.2. Zoning Compromises and Violations......Page 317
4.6.3. Impact of Zoning on Subsystem Grounding Architecture......Page 318
4.7. Equipment Enclosure and Signal Grounding......Page 321
4.7.1. External Signal and Safety Grounding Interconnects between Enclosures......Page 322
4.7.2. Equipment DC Power, Signal, and Safety Grounding......Page 323
4.7.3. Power Distribution Grounding Schemes in Integrated Clustered Systems......Page 326
4.7.4. Grounding of Equipment Enclosure Shield......Page 330
4.8.1. Grounding Ground Rules in Racks and Cabinets......Page 333
4.8.2. Ground Loops and their Mitigation in Racks and Cabinets......Page 335
4.9.1. “One Size Fits None”......Page 339
4.9.3. Clustered System......Page 340
4.9.4. Distributed System......Page 343
4.9.5. Nested-Distributed System......Page 344
4.9.6. Central System with Extensions......Page 345
Bibliography......Page 346
5.1. Objectives of Bonding......Page 348
5.2. Bond Impedance Requirements......Page 352
5.3. Types of Bonds......Page 354
5.3.1. Direct Bonds......Page 355
5.3.2. Indirect Bonds......Page 360
5.3.3. Bonding Impedance and Effectiveness......Page 362
5.4. Surface Treatment......Page 373
5.5. Dissimilar Metals Consideration: Corrosion Control......Page 376
5.5.1. Electrochemical Basis of Bond Galvanic Corrosion......Page 377
5.5.2. Electrochemical Series......Page 378
5.5.3. Galvanic Series......Page 379
5.5.4. Galvanic Couples......Page 380
5.5.5. Corrosion Protection......Page 385
Bibliography......Page 394
6.1. Introduction......Page 396
6.2.1. Objectives of Power System Earthing......Page 397
6.2.2. Faults in Power Supply Systems......Page 398
6.2.3. General Configuration of a Power Distribution System......Page 400
6.2.4. Electric Shock Hazards......Page 402
6.2.5. Methods of Power System Earthing......Page 408
6.2.6. The Ungrounded System......Page 410
6.3. Earthing for Low-Voltage Distribution System......Page 412
6.3.1. TN System......Page 413
6.3.2. TT System......Page 419
6.3.3. IT System......Page 421
6.3.4. Temporary Overvoltage in Low-Voltage Installations Due to Faults between High-Voltage Systems and Earth......Page 422
6.3.5. Earthing Systems and EMC......Page 427
6.3.6. Requirements for the Installation of Equipment with High Protective Earth Conductor Current......Page 429
6.3.7. Application of Residual-Current Devices for Shock Protection......Page 430
6.4.1. An Overview of the Lightning Phenomenon......Page 433
6.4.2. Lightning Attachment Point and Zones of Protection......Page 434
6.4.3. Components of the Lightning Protection System......Page 436
6.4.4. Influence of LV Earthing Schemes on Lightning Overvoltages......Page 441
6.5. The Earth Connection......Page 443
6.5.1. Resistance to Earth......Page 444
6.6. Types of Earth Electrodes......Page 445
6.6.1. The Earth Rods......Page 447
6.6.2. Earth Plates......Page 451
6.6.3. Horizontal Strip or Round Conductor Electrode......Page 452
6.6.4. The Mesh or Grid Earth Electrode......Page 457
6.6.5. The Ring Earth Electrode......Page 459
6.6.6. Foundation Earth Electrode......Page 462
6.7.1. Selection of Material......Page 465
6.7.2. Grounding Requirements of Power Distribution Systems......Page 466
6.7.3. Measures to Reduce Transient Impedance of Earth Electrodes......Page 468
6.7.4. Earthing Requirements for Lightning Protection......Page 470
6.7.5. Earth Potential Rise and Surface Potential Gradients......Page 472
6.8.1. Measurement of Soil Resistivity......Page 480
6.8.2. Measurement of Earth Resistance......Page 482
6.9. Reducing Earth Resistance......Page 487
6.10. Bonding to Building Structures......Page 488
Bibliography......Page 491
7.1. Introduction: System Interface Problems......Page 494
7.2. To Ground or Not To Ground (Cable Shields)......Page 495
7.3.1. Why Shield Cables?......Page 497
7.3.2. Fundamental Shielding Mechanisms......Page 498
7.3.3. Configuration of Shielded Cables......Page 500
7.3.4. Termination (Grounding) of Cable Shields—A Qualitative Discussion......Page 509
7.3.5. Termination (Grounding) of Cable Shields—A Quantitative Discussion......Page 515
7.3.6. Frequency Considerations in Cable Shield Termination......Page 523
7.4. Shield Surface Transfer Impedance......Page 535
7.4.1. Methods for Cable Shielding......Page 537
7.4.2. Shield Surface Transfer Impedance in Coaxial Lines......Page 539
7.4.3. Where Should a Shield of a Balanced Line be Terminated?......Page 542
7.4.4. Shield Termination—The Key to Optimal Shielding Performance......Page 548
7.4.5. Twisted Cables and the Effect of Grounding......Page 570
7.4.6. Strategies for Shield Termination in Common Types of Shielded Cables......Page 575
7.5.1. Interfacing of Low-Frequency Unbalanced Signal Circuits......Page 582
7.5.3. Interfacing of Equipment Containing Both Low- and High-Frequency Signals......Page 584
7.5.4. Interfacing of Broadband (Video) Signal Circuits......Page 586
7.5.5. Interfacing of Balanced Signal Circuits......Page 587
7.5.6. Effect of Interface Scheme on Magnetic Interference Susceptibility......Page 591
7.6.1. Measurement Accuracy Concerns......Page 594
7.6.2. Guard Shields and Instrumentation Wiring Shield Interconnection......Page 599
7.6.3. Grounding of Wiring Shields in Analog-Data Acquisition Systems......Page 602
Bibliography......Page 611
8.1. Filtering and Transient-Voltage Suppression—Complementary Techniques to Shielding......Page 614
8.3.1. Fundamental EMI Filter Devices and Circuits......Page 615
8.3.2. Special EMI Filter Applications......Page 622
8.3.3. Transient-Voltage Protection Devices and Circuits......Page 626
8.4.1. When is Ground Not Equal to Ground?......Page 632
8.4.2. Practices for Grounding of Terminal Protection Devices (TPDs)......Page 639
8.4.3. Terminal Protection Devices (TPDs) Installation and Mounting Practices......Page 644
Bibliography......Page 648
9.1. Interference Sources on PCBs......Page 650
9.2. “Grounding” on PCBs......Page 655
9.3. Signal Propagation on PCBs......Page 656
9.3.1. Circuit Representation of Transmission Lines on PCBs......Page 657
9.3.2. Electromagnetic Field Representation of Transmission Lines on PCBs......Page 658
9.3.3. Equivalence of Power and Ground Planes as Return Paths for High-Speed Signal Propagation......Page 661
9.3.4. Common Transmission Line Configurations on PCBs......Page 664
9.3.5. Return Current Path on Printed Circuit Boards......Page 670
9.3.6. Return Current Distribution......Page 677
9.3.7. Crosstalk Mechanisms on PCBs......Page 679
9.3.8. Common Impedance Coupling on PCBs......Page 684
9.3.9. Consequences of Transmission Line Topology on EMI and Crosstalk Control......Page 685
9.4. Return Path Discontinuities: “Mind the Gap”......Page 687
9.4.1. Undesired Effects of Traces Crossing Gaps in the Reference Planes: “Seeing is Believing”......Page 691
9.4.2. Reference Plane Discontinuities and Mitigation Strategies......Page 702
9.4.3. Differential Lines Crossing Gaps in Reference Planes......Page 756
9.5. Delta-I (ΔI) and Simultaneous Switching Noise (SSN) in PCBs......Page 768
9.5.1. ΔI Noise Generation in Signal I/O Circuits......Page 770
9.5.2. ΔI Noise Generation Mechanism in the Power Distribution Network (PDN)......Page 777
9.5.3. Effective Management of ΔI Noise Effects in Signal Circuits......Page 779
9.5.4. Control of Delta-I (ΔI) Noise in the Power Distribution Network......Page 787
9.5.5. Parallel-Plate Waveguide (PPW) Noise Mitigation Using Electromagnetic Band Gap (EBG) High-Impedance Structures (HIS)......Page 806
9.5.6. Parallel-Plate Waveguide (PPW) Noise Mitigation Using Virtual Islands and Shorting Via Arrays......Page 833
9.6. Return Planes and PCB Layer Stack-up......Page 845
9.6.1. Image Planes......Page 846
9.6.2. Frequently Used PCB Layer Stack-up Configurations......Page 849
9.6.3. Local Ground Structures......Page 852
9.6.4. Shield Traces......Page 858
9.7. Cuts and Splits in Return Planes......Page 865
9.7.1. Circuit Partitioning, Floating, and Moating......Page 867
9.7.2. Circuit Isolation......Page 868
9.7.3. Bridging the Gap......Page 870
9.8. Grounding in Mixed-Signal Systems......Page 874
9.8.2. Grounding Analog Circuits......Page 875
9.8.4. Grounding in Mixed-Signal PCBs: “To Split or Not to Split (the Ground Plane)?”......Page 876
9.8.5. The Mystery of A/D and D/A Converters Solved......Page 881
9.8.6. Grounding Scheme for a Single ADC/DAC on a Single PCB......Page 885
9.8.7. Grounding Scheme for Multiple ADCs/DACs on a Single PCB......Page 887
9.8.8. Grounding Scheme for ADCs/DACs on Multiple PCBs......Page 893
9.9. Chassis Connections (“Chassis Stitching”)......Page 898
9.9.1. Purpose of Stitching PCB Return Planes to Chassis......Page 899
9.9.2. Direct Stitching of Return Planes to Chassis......Page 905
9.9.3. Hybrid Techniques for Stitching of Return Planes to Chassis......Page 906
9.9.4. Capacitive Stitching of Return Planes to Chassis......Page 911
9.9.5. Controlling Parallel-Plate Waveguide (PPW) Noise in the PCB-Chassis Cavity......Page 913
9.9.6. Benefits of Reduced Spacing between a PCB and the Chassis......Page 919
9.9.7. Daughter and Mezzanine Boards Ground Stitching......Page 920
9.9.8. PCB Heat Sinks Grounding Considerations......Page 922
Bibliography......Page 930
10. Integrated Facility and Platform Grounding System......Page 936
10.1. Facility Grounding Subsystems......Page 937
10.1.2. Fault Protection Subsystem......Page 938
10.1.4. Signal Reference Subsystem......Page 939
10.2. Grounding Requirements in Buildings or Facilities......Page 942
10.2.1. Grounding of Power Distribution Systems in Buildings......Page 943
10.2.2. Grounding in Industrial Facilities......Page 946
10.2.3. Grounding for Information Technology Equipment......Page 948
10.2.4. Grounding in Telecommunication and C(3)I (Command, Control, Communications, and Intelligence) Facilities......Page 951
10.2.5. Grounding in HEMP-Protected and Secure C(3)I Facilities......Page 959
10.2.6. Grounding of Instrumentation and Control Equipment Collocated with High-Voltage Power Apparatus......Page 966
10.3.1. Nature and Sources of Static Electricity......Page 969
10.3.2. Susceptibility to ESD......Page 971
10.3.3. ESD Protected Areas (EPAs) in Facilities......Page 974
10.3.4. ESD Protective Tools, Materials, and Equipment......Page 975
10.3.5. Essentials of Grounding for ESD Control......Page 979
10.3.6 Safety Considerations in ESD Grounding......Page 981
10.4.1. Grounding in Transportable Tactical Shelters......Page 983
10.4.2. Grounding in Aircraft......Page 994
10.4.3. Grounding in Spacecraft......Page 1000
10.4.4. Grounding in Ships......Page 1006
Bibliography......Page 1017
APPENDIX A. Glossary of Grounding-Related Terms and Definitions......Page 1022
APPENDIX B. Acronyms......Page 1040
APPENDIX C. Symbols and Constants......Page 1044
D.1. ANSI Standards......Page 1046
D.4. CENELEC and ETSI Publications......Page 1047
D.5. IEC Standards......Page 1048
D.6. IEEE Standards......Page 1051
D.7. International Space Station (ISS) Program Standards......Page 1053
D.8. ITU-T Recommendations......Page 1054
D.9. Military Standards and Handbooks......Page 1055
D.10. NASA Standards and Handbooks......Page 1061
D.13. TIA/EIA Standards......Page 1062
D.15. Other (Miscellaneous) Standards......Page 1063
APPENDIX E. On the Correspondence between Ohm’s Law and Fermat’s Least Time Principle......Page 1064
E.2. Statement of the LT/MP Principle......Page 1065
E.3. Derivation of the Equivalence between Ohm’s Law and Fermat’s Least Time Principle......Page 1066
E.4. Equivalence of Ohm’s Law and the LT/MP Theory......Page 1068
Bibliography......Page 1069
F.1. Background......Page 1070
F.2. Ports and Interaction Matrices......Page 1071
F.3. The Scattering Matrix and S Parameters......Page 1072
F.3.1. The Scattering (S) Matrix......Page 1073
F.3.2. S(21), or “Forward Transmission Gain/Loss”......Page 1075
F.3.4. S(22), or “Output Return Loss”......Page 1076
F.3.5. S(12), or “Reverse Gain and Reverse Isolation”......Page 1077
F.5.1. The Loss-Free Network......Page 1078
F.5.4. Radiation Loss......Page 1079
Bibliography......Page 1080
Index......Page 1082