Introduction to RF Design Using EM Simulators (Artech House Microwave Library)

309 Pages·2011·8.41 MB·English

by  Hiroaki Kogure

Introduction to RF Design
Using EM Simulators
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Introduction to RF Design
Using EM Simulators
Hiroaki Kogure
Yoshie Kogure
James C. Rautio
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A catalog record for this book is available from the U.S. Library of Congress.
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A catalogue record for this book is available from the British Library.
Cover design by Adam Renvoize
ISBN 13: 978-1-60807-155-5
(KAITEI) DENJIKAI SHIMYURETA DE MANABU KOSHUHA NO SEKAI
Copyright © 2010 Hiroaki KOGURE and Yoshie KOGUREAll rights reserved.
Original Japanese edition published in 2010 by CQ Publishing Co., Ltd.
English translation rights arranged with CQ Publishing Co., Ltd. through Japan UNI
Agency, Inc., Tokyo
All rights reserved. Printed and bound in the United States of America. No part of this book
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10 9 8 7 6 5 4 3 2 1
Contents
Preface xiii
1 Electricity with Good Manners 1
1.1 From Source to Load, Nicely 1
1.1.1 Parallel Lines Model 1
1.1.2 Model of a Light bulb and a Battery 1
1.1.3 Electric Field in the Vicinity of the Wires 3
1.1.4 Electric Field Due to AC Power 4
1.2 Transmission Lines with Widespread Fields 5
1.2.1 Two Parallel Wires, the Basis of the Transmission Line 5
1.3 Transmission Lines with Confined Fields 5
1.3.1 Model of a Waveguide Tube 6
1.3.2 Observation of Electric Fields, Magnetic Fields,
1.3.2 and Currents 7
1.3.3 Tubes Can Be Transmission Lines 9
1.4 What Is a Microstrip Line? 9
1.4.1 Microstrip Is Great for Printed Circuit Boards 9
1.4.2 Fundamentals of the Microstrip Line 10
1.5 Characteristics of Microstrip Lines 12
1.5.1 What Is Characteristic Impedance? 12
1.5.2 Electromagnetic Field of a Transmission Line 13
1.5.3 TEM Mode 13
1.5.4 Quasi-TEM Mode 15
1.6 Confirming Results of This Chapter by Simulation 15
1.6.1 Modeling a Microstrip Line 15
1.6.2 Understanding Our MSL—Obtaining S-Parameters 22
1.6.3 Characteristic Impedance of the MSL 24
v
vi Introduction to RF Design Using EM Simulators
1.7 Summary 26
2 Electricity with Bad Manners 27
2.1 What Could Possibly Go Wrong? 27
2.1.1 Transmission Line Bend 27
2.1.2 Looking at the Current Distribution 28
2.1.3 Viewing Electric and Magnetic Fields 29
2.2 Radiation from Substrates 31
2.2.1 Higher Frequencies Usually Mean More Radiation 31
2.3 Larger Reflection Coefficient Means… 33
2.3.1 The Right Angle Bend Has Problems 33
2.3.2 Standing Waves Come from Reflection 34
2.3.3 How Is a STanding Wave Generated? 35
2.4 Meander Lines 38
2.4.1 Electric Field Representation 39
2.5 What Causes Bad Manners? 40
2.5.1 The Normal Mode and the Common Mode 40
2.5.2 Location of the Loop and Common Mode Current 41
2.5.3 Effects of Common Mode Current 42
2.5.4 Relation Between Common Mode Current and
Radiation 42
2.6 Considering Multilayer Substrates 44
2.7 Where Does the Radiation Go? 44
2.8 Maxwell Predicted Displacement Current 47
2.8.1 Maxwell’s Achievements 47
2.8.2 Maxwell’s Hypothesis 47
2.8.3 Electromagnetic Waves and Maxwell 48
2.9 Transmission Lines Versus Antennas 49
2.9.1 What Is an Antenna? 49
2.9.2 A Transmission Line or an Antenna? 49
2.9.3 Discovery of Electromagnetic Waves 50
2.10 Skin Depth 50
2.11 Confirming Results of This Chapter by Simulation 51
Contents vii
2.11.1 Draw a Right-Angle Bend 51
2.11.2 The Effect of Cutting Corners 52
2.12 Summary 55
3 What Happens at High Frequency? 57
3.1 Scattering Parameters 57
3.1.1 Definition of S-Parameters 57
3.2 Let’s Use the Network Analyzer 59
3.2.1 The Importance of Calibration 60
3.2.2 De-Embedding and Calibration 61
3.3 S-Parameters of Four Bent Coupled Lines 61
3.3.1 How to Evaluate S-Parameters 63
3.4 More Complicated Circuit Examples 64
3.4.1 PCB Interconnect Example 64
3.4.2 Searching for Problems by Viewing the
3.4.2 Current Distribution 65
3.4.3 Interpretation of S-Parameters 66
3.5 Ground Bounce and Ground Loops 66
3.5.1 Example of Ground Bounce and Its Analysis 67
3.6 Some Definitions of Characteristic Impedance 70
3.6.1 Characteristic Impedance of the Waveguide Tube 70
3.6.2 So How Do We Apply a Voltage to a Waveguide Tube? 72
3.6.3 A Useful Method Due to Heaviside 72
3.6.4 Matching Source to Load 74
3.6.5 Why Is 50Ω the Standard? 75
3.6.6 Characteristic Impedance of a Microstrip Line 77
3.7 Confirming Results of This Chapter by Simulation 78
3.7.1 Modeling the Discontinuity 78
3.7.2 Simulation Result Including Port Connecting
Transmission Lines 79
3.7.3 Surface Current Distribution 80
3.7.4 Current Distribution Animation 81
3.7.5 Display Subsections 81
3.7.6 Simulation with Removal of Port Connecting
Transmission Lines 82
3.7.7 Comparing S-Parameter Results 84
viii Introduction to RF Design Using EM Simulators
3.7.8 Coupled-Line Right-Angle MSL Bend 85
3.7.9 MSL Crosstalk Reduction 86
3.7.10 Simulation of Crosstalk for More Than Two Lines 87
3.8 Summary 90
4 What Is Different About High-Frequency Circuits? 93
4.1 Electromagnetics and Circuit Theory 93
4.1.1 Microstrip Lines Are Distributed Circuits 93
4.1.2 Treating a Circuit on a Printed Circuit Board as a
Transmission Line 94
4.2 Design of Microwave Circuits 94
4.3 Bent Coupled Lines Again 95
4.3.1 Analysis Using SPICE 97
4.4 A High-Speed Digital Circuit 97
4.4.1 Guidelines for Frequency Selection 99
4.4.2 Generation of a SPICE File 100
4.4.3 The RLGC Matrix 103
4.5 Simulation of Filters 105
4.5.1 Analysis of a Bandpass Filter 105
4.5.2 Dividing a Circuit 105
4.5.3 Creation of Geometry File 106
4.5.4 Simulating the Divided Circuit 107
4.5.5 Key Point on Where to Set Dividing Lines 108
4.5.6 Evaluation of the Result of Simulation 109
4.6 Simulation of a T-Type Attenuator 111
4.6.1 Construction of a Circuit 112
4.6.2 Creation of a Netlist File 112
4.6.3 Method Using Internal Ports 114
4.7 Simulation of Meta-Materials 114
4.7.1 What Is a Left-Handed System? 114
4.7.2 Realization of Meta-Materials 115
4.7.3 Fields in a Left-Handed System 116
4.8 Confirming This Chapter by Simulation 119
4.8.1 SPICE Subcircuit of a Right-Angle MSL Bend 119
4.8.2 Create a SPICE Subcircuit as a Symbol 122
Contents ix
4.8.3 Using Parts 124
4.8.4 Register the Subcircuit LBEND2.lib in the
Circuit Schematic 126
4.9 Summary 128
5 High Frequencies and Undesired Radiation 131
5.1 Understanding Through Visualization 131
5.1.1 Necessity of Impedance Matching 131
5.1.2 Simulation of MSLs 132
5.1.3 Current on the Ground Plane 133
5.2 Simple MSL Model 133
5.2.1 Wavelength in Vacuum and Dielectrics 136
5.3 Undesired Radiation from a Substrate with Ground Slit 137
5.3.1 Interpretation of S-Parameters 137
5.3.2 Difference Due to the Location of the Slit 139
5.3.3 Difference Due to Slit Direction 139
5.3.4 Electromagnetic Field Around the Substrate 140
5.3.5 What Happens at Frequencies of Low Reflection? 142
5.4 Electromagnetic Shielding and Radio Wave Absorption 144
5.4.1 A Physical Quantity to Represent the Effectiveness
of a Shield 144
5.4.2 Effectiveness of a Magnetic Shield 145
5.4.3 The Effect of High Frequency on a Magnetic Shield 146
5.4.4 A Standing Wave in Space 146
5.4.5 Absorption of Electromagnetic Waves 147
5.5 Confirming This Chapter by Simulation 149
5.5.1 Drawing the MSL Ground Plane Including the Slit 149
5.5.2 Add the Ground Plane and the MSL Ports 151
5.5.3 Including the Effect of Radiation 152
5.5.4 Simulate a Radiating MSL 154
5.6 Summary 158
6 Understanding the Differential Transmission Line 161
6.1 Smaller, Better, Faster 161
6.1.1 What Is a Differential Transmission Line? 161