Transcript Transmission Lines - Engineering Class Home Pages

EE 448
University of Southern California
Department of Electrical Engineering
Dr. Edward W. Maby
Class #1
11 January 2005
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Course Personnel
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Dr. Edward W. Maby (Instructor)
[email protected] 740-4706
 Office Hours: MW 1:00 - 2:00 PHE 626
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Clint Colby
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[email protected]
Tyler Rather
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[email protected]
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Grading Policy
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Midterm 1
Midterm 2
Homework
Final Exam
25%
25%
15%
35%
17 February
24 March
10 May
No Make-Up Exams
Homework Conditions Borderline Grades
Same “Curve” for Graduate Students
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Course Objectives
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Circuit Concepts for RF Systems
Transmission Lines, Impedance Matching
 Noise and Distortion Analysis
 Filter Design
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RF System Components
Low-Noise Amplifiers, Power Amplifiers
 Mixers and Oscillators
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Elementary Transmitter/Receiver Architectures
and Their Board-Level Implementation
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Why RF ?
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Ever-Growing Wireless Applications
Personal Communication Systems
 Satellite Systems
 Global Positioning Systems
 Wireless Local-Area Networks
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Strong Demand for Wireless Engineers
Digital is HOT
 Analog is COOL
 RF Design is an ART
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Emphasis ???
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Designing RF Integrated Circuits
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Designing With RF Integrated Circuits
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Some Engineers
More Engineers
Difficult to Satisfy Both Objectives
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EE 448 Textbooks
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The Design of CMOS Radio-Frequency Integrated Circuits
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Planar Microwave Engineering: A Practical Guide to Theory
Measurements and Circuits
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Arshad Hussain
Microwave and RF Design of Wireless Systems
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W. Alan Davis and Krishna K. Agarwal
Advanced RF Engineering for Wireless Systems and Networks
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Thomas H. Lee
Radio Frequency Circuit Design
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Thomas H. Lee (required)
David M. Pozar
High-Frequency Techniques
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Joseph F. White
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Some Good Advice …
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Read the Syllabus
Come to Class
(Come to Class Early)
Do the Homework
(But Not One Hour Before a Deadline)
(And Don’t Give Up Easily)
Enjoy the Course !
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Basic Radio Systems
Data In
Modulator
IF Filter
Mixer
Bandpass
Filter
Power
Amplifier
X
Local
Oscillator
Transmitter
Bandpass Low-Noise
Filter
Amplifier
Mixer
IF Filter
IF
Amplifier
Demodulator
X
Receiver
University of Southern California - EE 448 - Class #1Slide #
Local
Oscillator
Data Out
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Connecting the Boxes
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Antenna RF Link Between Transmitter
and Receiver
(Marginal Issue for EE 448)
Transmission-Line Connections Between
Internal Transmitter/Receiver Components
l = Velocity / Frequency
 Circuit Dimensions Comparable to l at High
Frequencies (>> 1 GHz)
 “Distributed” Circuit Behavior
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Transmission-Line Model
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Two “Wires” with Uniform Cross Section
L (inductance), C (capacitance) per unit length
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Transverse Electromagnetic Fields
Quasi-Static Solutions
L = L (m, xy geometry), C = C (e, xy geometry),
LC=me
R (resistance), G (conductance) per unit length
(Consider Physical Mechanisms Later)
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Telegraphers Equations
(Heaviside, 1880)
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Power Implications
Dissipated
Power
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Change in Stored
Linear Energy Density
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Time-Domain Solutions
(No Loss)
Wave Equation
Forward Wave
Reverse Wave
Velocity
No Wave Dispersion (Corruption) During Propagation
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Frequency Domain
v and i have
Time Dependence
(Similar equation for i)
Propagation Constant
R and G may be w dependent
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Freq.-Domain Solutions
Forward
Reverse
(V+ and V- are Fourier Amplitudes)
Similar form for i (z,t); however,
Characteristic
Line Impedance
(Zo Follows Directly from Transmission-Line Model)
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Low-Loss Propagation
Assume
(OK to 10 GHz)
For Line Length l,
• Attenuation in dB
• Attenuation in nepers
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Velocities and Wavelength
Fixed Phase Angle
Phase Velocity:
w Independent
No Dispersion
Group Velocity:
(Applies to Modulated Signal)
Wavelength:
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Historical Remarks
(Transatlantic Cable)
First Telegrapher’s Equations: (No L or G)
Prof. William Thomson (Later Lord Kelvin) 1854
Diffusion
Equation
(Applies to Most Ordinary IC Interconnects)
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Diffusion Solutions
Unit-Step Input:
For line length l, imax at
Pulse Input:
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Diffusion “Velocity”
Sinusoidal Input:
“Velocity”
Dispersion, High-Frequency Attenuation
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Did Engineers Care?
Dr. Edward Orange Wildman Whitehouse M.D.
Chief Electrician, Atlantic Telegraph Company, 1856
On Thomson’s Results …
“In all honesty, I am bound to answer, that I believe nature
knows no such application of that law; and I can only regard
it as a fiction of the schools, a forced and violent adaptation
of a principle in Physics, good and true under other circumstances, but misapplied here.” Nahin, p. 34
First Transatlantic Cable (1858)
Whitehouse: Long Cable Requires Large-Voltage Input
2000-V “Stroke of Lightning” per Pulse (Obviously)
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What Happened Next?
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Queen Victoria and James Buchanan Exchange Messages
Great Celebration, Public Pleased
Cable Insulation Fails, Cable Dead, Public Angry
Boston Headline: Was the Atlantic Cable a Humbug?
Investor: Was Cyrus Field an Inside Trader?
Further Experiments: High Voltage Not Necessary
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Whitehouse Fired
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Second Transatlantic Cable Successful (1866)
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Minimal Dispersion ?
Telegraph Lines Make Poor Telephone Lines
(Bell Fails to Propagate Voice Over Atlantic Cable - 1877)
?
Heaviside (1887)
Increase L by Adding Series Loading Coils at l/4 Intervals
Improve Audio Bandwidth, But Suppress High Frequencies
H88 Standard (88 mH at 6000-foot Intervals) Bad for DSL
University of Southern California - EE 448 - Class #1Slide #
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Dispersion - Skin Effect
Skin Depth
Real Part:
Imaginary Part:
Amplitude Distortion
Phase Distortion
Rise Time
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Dispersion - Dielectric Loss
General Relation for Capacitance:
Dielectric Constant Has Real and Imaginary Parts
(Loss Tangent)
Loss
Dielectric Loss Overtakes Skin-Depth Loss (f >> 1 GHz)
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Digital Digression
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Dispersion Promotes Inter-Symbol Interference
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Equalization at Receiver
Correct for Group Delay
 Correct for Amplitude Distortion
 Difficult for Very-High Data Rates
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Pre-Emphasis (Pre-Distortion) at Transmitter
Increase Pulse Amplitude After Transition
 MAX3292 (for RS-485)
 See Widmer et al. (IBM)

IEEE JSSC 31, 2004 (1996)
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Why 50 Ohms?
(Lee, pp. 229-231)
Consider Coaxial Cable With Inner and Outer Diameters a and b
Maximum Deliverable Power:
Zo = 30 W
Minimum Attenuation:
Zo = 77 W
(75 W - Cable TV)
Compromise:
Zo = 50 W
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Microstrip Lines
w
e
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h
Important Substrate Properties
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Substrate
Relative Dielectric Constant
Loss Tangent
Thermal Conductivity
Dielectric Strength
Numerous Design Equations for Zo and Effective e
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See Davis and Agarwal, pp. 71-74; Chang, pp. 43-49
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Calculator: http://mcalc.sourceforge.net/#calc
University of Southern California - EE 448 - Class #1Slide #
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Design Formulas
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Define
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Then
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Assumes “Narrow” Lines
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References
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(Other than course texts)
Richard B. Adler, Lan Jen Chu, and Robert M. Fano,
Electromagnetic Energy Transmission and Radiation (1960)
Paul J. Nahin, Oliver Heaviside: The Life, Work, and Times
of an Electrical Genius of the Victorian Age (1988)
Henry M. Field, History of the Atlantic Telegraph (1866)
Kai Chang, RF and Microwave Wireless Systems (2000)
Richard E. Matick, Transmission Lines for Digital and
Communication Networks (1969)
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