EE 202L Linear Circuits Class #1
Course Personnel Prof. Edward Maby maby@usc.edu 0-4706 Office Hours: TTh 1:00-2:00 PHE 606 Dr. Douglas Burke burked@usc.edu 0-4711 Office Hours: TTh 12:30-2:00 PHE 430 Teaching Assistants Anton Shkel shkel@usc.edu Yongkui Tang yongkuit@usc.edu University of Southern California - EE 202L - Class #1Slide #
Resources The Analysis and Design of Linear Circuits R. E. Thomas, A. J. Rosa, and G. L. Toussant 7th Edition Digital Edition Available See Syllabus for Other Readings http://ee-classes.usc.edu/ee202 Lecture Slides Supplementary Notes and Handouts SPICE Documentation University of Southern California - EE 202L - Class #1Slide #
Grading Policy Midterm Exam #1 (26 September) 20% Midterm Exam #2 (24 October) 20% Circuit Boot Camp 15% Homework 10% Class Exercises, Labs, Projects 10% Final Exam (University Schedule) 25% No Make-Up Exams Homework Conditions Borderline Grades University of Southern California - EE 202L - Class #1Slide #
Circuit Bootcamp 30 Analysis Problems in Sets of 10 22 January - Set 1 Due 29 January - Set 2 Due 5 February - Set 3 Due Random Circuit Parameters! Receive Excel Files with Parameters Return Excel Files with Answers Right or Wrong Answers Half Credit for Sign Error Only Develop Important Skills for EE 202L
Some Good Advice Read the Syllabus Come to Class Do the Homework (But Not One Hour Before a Deadline) (And Don t Give Up Easily) No Texting During Class! Enjoy the Course! University of Southern California - EE 202L - Class #1Slide #
Administrative Questions?
Electrical Engineering? Electrical Power Generate Distribute Condition Utilize Classical Focus Machinery Lighting Heating University of Southern California - EE 202L - Class #1Slide #
Electrical Engineering? Electrical Information Generate Distribute Condition Utilize Systems Focus Communications Sensing and Control Computer Engineering Biomedical Applications University of Southern California - EE 202L - Class #1Slide #
A Fundamental Discipline: Networks Communications Data Flows Web Linkages System Organizations Social Structures Distribution Strategies Linguistic Syntax Branch Node Electrical Networks? Network
Electrical Networks Function as Circuits Circuitus (Latin, Going Round) Loops Have Currents Flow of Positively Charged Particles Loops Ensure Charge Neutrality Loop Current i a Altitude v a Node Voltage Nodes Have Voltages Measure of Electric Potential Potential Difference Flow Branch Elements Constrain Currents and Voltages Branch Element
Circuits Matter Not in Circuit Happy Bird High Voltage High Voltage Dead Bird
Nodes vs. Connections Connection Point Jump Node
Branch-Element Perspective Current Through a Branch Element i a i 1 i 1 = i a i b i b Voltage Across a Branch Element v 1 = v a v b v 1 v a v b
Units and Magnitudes Currents Expressed in Amperes (Amps) - A 1 A = 1 coulomb / s = 6.25 x 10 18 fundamental charges / s 1 ma (milliamp) = 10-3 A Common for 1 ua (microamp) = 10-6 A Electronic Circuits 1 na (nanoamp) = 10-9 A 1 pa (picoamp) = 10-12 A 1 fa (femtoamp) = 10-15 A i = dq dt Voltages Expressed in Volts - V 1 kv (kilovolt) = 10 3 V Common for Power Circuits Positive or Negative Values are Possible!
Three Pillars of Circuit Theory Kirchhoff s Current Law Kirchhoff s Voltage Law Ohm s Law Georg Ohm Gustaf Kirchhoff All of Electrical Circuit Theory Rests on These Three Laws
Kirchhoff s Current Law (KCL) The Sum of Branch Currents into a Node is Zero. i 1 i 2 Variations i 1 i 2 i 3 =0 i 1 i 3 = i 2 i 1 i 2 i 3 =0 Signs Matter The Sum of Outward Branch Currents is Zero. What Goes In Comes Out
Exercise 1 Determine i 1,i 2,i 3,i 4 i 1 5 ma i 3 2 ma i 2 i 4 Independent Current Source 1 ma
Kirchhoff s Voltage Law (KVL) The Sum of Voltages Around a Loop is Zero. I E dl =0 Start Here v 1 v 3 v 2 Clockwise v 1 v 2 v 3 =0 No Magnetic Field Variations Signs Matter v 3 v 2 v 1 =0 v 1 = v 2 v 3 Counterclockwise Balance Both Sides of the Loop
Exercise 2 Determine v 1,v 2,v 3 v 1 3 10 4 v 2 Independent Voltage Source v 3
Branch Elements: Resistors v = ir Ohm s Law R is Resistance in Ohms (Ω) Convention: Positive Algebraic Current Flows from to - Pick i Direction Then v as Shown Pick v Direction Then i as Shown i R v R i v Signs Matter
Resistor Structure Composition (old) Poor Tolerance High-Voltage Film Good Tolerance Good Tempco Wire-Wound High-Current Applications Bulky
Resistor Packages Axial Lead Surface Mount Arrays Potentiometers
Resistor Code R = ab 10 c R = abc 10 d Bright Boys Rave Over Young Girls But Veto Getting Wed University of Southern California - EE 202L - Class #1Slide #
Resistor Values E_ Standards Even Partitions of a Logarithmic Scale E24 for Lab Resistors Other Characterizations Power Rating Tempco (ppm/ o C)
Branch Elements: Sources Independent Current Source Specify i (not v) 2 ma Special Case i = 0 Open Circuit Independent Voltage Source Specify v (not i) 4 V Special Case v = 0 Short Circuit Dependent Current Source i = f (Other Circuit Variables) Dependent Voltage Source v = f (Other Circuit Variables) f ( ) f ( ) Useful for Modeling Electronic Devices
Physical Sources R1 v 1 R1 R1 Voltage Sources Current Sources Battery Photodetector R 3 v ` vx i out R L R 2 v b R 2 va Electronic Instrument Electronic Circuit
Improper Source Combinations Current-Source Tie Set 1 3 Voltage-Source Loop Set 2 KCL Violated! 3 6 KVL Violated!
Branch Elements: Switches Open-Short Transitions, Loop Creators / Destroyers Mechanical Switches Electrical Switches Transistors
Power Rate of Energy Transfer xp = vi Expressed in Watts Tellegen s Theorem v k i k =0 Power is Conserved Resistors Dissipate Power (Heat) xvi>0 xp = vi= v2 R = i2 R Sources Generally Supply Power xvi<0 xvi>0 Possible v v R i i Signs Matter
Exercise 3 (Design Problem) Determine v x 3 v 3 > 0 P 3 = 12 watts 2 1 6 v x v 3 3 Mark up the Circuit Diagram!
Circuit of Exercise 3 (Analysis) Determine P 3 i 4 3 i x i 2 v 4 2 i 1 1 i 5 6 v 2 v 1 v x = 21 A B C D v 3 v 5 3 i 3 Not so Easy! 6 Elements, 12 Unknowns, 12 Equations
Circuit of Exercise 3 (Branch Constraints) v x = 21 v 1 =1i 1 v 2 =2i 2 v 3 =3i 3 v 4 =3i 4 v 5 =6i 5 i x i 2 i 4 3 v 4 2 i 1 1 i 5 6 v 2 v 1 v x = 21 A B C D v 3 v 5 3 i 3
Circuit of Exercise 3 (KCL) A : i x i 2 =0 B : i 2 i 1 i 4 =0 C : i 1 i 3 i 5 =0 N Nodes i 4 (N - 1) KCL Equations 3 i x i 4 i 3 i 5 =0 i x i 2 v 4 2 i 1 1 i 5 6 v 2 v 1 v x = 21 A B C D v 3 v 5 3 i 3 KCL at Node D Dependent on KCL Equations at Other Nodes
Circuit of Exercise 3 (KVL) v x = v 2 v 1 v 3 v 4 = v 1 v 5 B Elements (B - N 1) KVL Equations v 3 = v 5 i 4 3 Solve v 3 =6V P 3 = 12 W i x i 2 v 4 2 i 1 1 i 5 6 v 2 v 1 v x = 21 A B C D v 3 v 5 3 i 3 There Must Be an Easier Way! (Next Time)