Timing Analysis and Simulation for Signal Integrity Engineers

266 Pages·2007·3.183 MB·English

by  Greg Edlund

Timing Analysis and Simulation
for Signal Integrity Engineers

Timing Analysis and
Simulation for Signal
Integrity Engineers
Greg Edlund
An Imprint of Pearson Education
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Library of Congress Cataloging-in-Publication Data
Edlund,Greg.
Timing analysis and simulation for signal integrity engineers / Greg Edlund.
p. cm.
ISBN 0-13-236504-9 (hbk. :alk. paper) 1. Timing circuits—Design and construction. 2. Digital electronics—Design and
construction. 3. Signal processing—Digital techniques. I. Title.
TK7874.65E36 2007
621.3815—dc22
2007030307
Copyright ©2008 Pearson Education,Inc.
All rights reserved. Printed in the United States of America. This publication is protected by copyright,and permission must be ob-
tained from the publisher prior to any prohibited reproduction,storage in a retrieval system,or transmission in any form or by any
means,electronic,mechanical,photocopying,recording,or likewise. For information regarding permissions,write to:
Pearson Education,Inc.
Rights and Contracts Department
501 Boylston Street,Suite 900
Boston,MA 02116
Fax [phone]
ISBN-13:978-0-132-36504-8
ISBN-10:0-13-236504-9
Text printed in the United States on recycled paper at Courier Westford,Westford Massachusetts.
First printing October,2007
Editor-in-Chief:Mark Taub Indexer:Lisa Stumpf Editorial Assistant:Michelle Housley
Acquisitions Editor:Bernard Goodwin Proofreader:Williams Woods Publishing Cover Designer:Alan Clements
Managing Editor:Gina Kanouse Technical Reviewers:Bob Haller,Lynne Composition:Bronkella Publishing
Senior Project Editor:Kristy Hart Green,Mike Resso,Andy Martwick,
Copy Editor:Water Crest Publishing Jim Peterson
“Our planet is a lonely speck in the great enveloping cosmic dark.
In our obscurity,in all this vastness,there is no hint that help will come
from elsewhere to save us from ourselves.”
“It has been said that astronomy is a humbling and character building
experience. There is perhaps no better demonstration of the folly of human
conceits than this distant image of our tiny world. It underscores our
responsibility to deal more kindly with one another,and to preserve and cherish
the pale blue dot,the only home we’ve ever known.”
—Carl Sagan,from a public lecture delivered on October 13,1994,at Cornell
University
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Contents
Preface xiii
Acknowledgments xvi
About the Author xix
About the Cover xx
1 Engineering Reliable Digital Interfaces 1
A Sadly Familiar Tale 3
Power On 4
The Long Reach of Legacy Design 6
Reflections on a Near Disaster 8
Motivations to Develop a Simulation Strategy 9
The Boundaries of Simulation Space 10
vii
viii Timing Analysis and Simulation for Signal Integrity Engineers
2 Chip-to-Chip Timing 13
Root Cause 14
CMOS Latch 14
Timing Failures 18
Setup and Hold Constraints 19
Common-Clock On-Chip Timing 22
Setup and Hold SPICE Simulations 25
Timing Budget 26
Common-Clock IO Timing 28
Common-Clock IO Timing Using a Standard Load 32
Limits of the Common-Clock Architecture 38
3 Inside IO Circuits 39
CMOS Receiver 40
CMOS Differential Receiver 42
Pin Capacitance 43
Receiver Current-Voltage Characteristics 45
CMOS Push-Pull Driver 46
Output Impedance 48
Output Rise and Fall Times 49
CMOS Current Mode Driver 51
Behavioral Modeling of IO Circuits 53
Behavioral Model for CMOS Push-Pull Driver 54
Behavioral Modeling Assumptions 56
Tour of an IBIS Model 56
IBIS Header 61
IBIS Pin Table 61
IBIS Receiver Model 62
IBIS Driver Model 63
Behavioral Modeling Assumptions (Reprise) 65
Comparison of SPICE and IBIS Models 66
Accuracy and Quality of IO Circuit Models 68
Contents ix
4 Modeling 3D Discontinuities 73
Beyond Transmission Lines 74
Finite Difference Time Domain Method 75
Solo Flight in a 3D Field Solver 79
Coaxial Transmission Line 80
Boundary Conditions 82
Waveguide Ports 83
Stimulus Function 84
Mesh Density 85
Running the Solver 86
Port Signals 87
S-Parameters 88
Energy 89
Field Visualization 91
Coaxial Discontinuity 94
Formation of Reflection 96
S-Parameters and Their Explanation 97
5 Practical 3D Examples 101
Coupled Differential Vias 102
Mechanical Drawings 103
Ports 106
Mesh Density 108
Sanity Check 113
Documentation 114
Pre-Flight Checklist 116
Land Grid Array Connector 118
Mechanical Trade-Offs 120
Electrical Characterization 120
3D Modeling Decisions 122
Test Card Design 125
Model-to-Hardware Correlation 128