EE 202L Linear Circuits. Class #1

Transcription

1 EE 202L Linear Circuits Class #1

2 Course Personnel Prof. Edward Maby Office Hours: TTh 1:00-2:00 PHE 606 Dr. Douglas Burke Office Hours: TTh 12:30-2:00 PHE 430 Teaching Assistants Anton Shkel Yongkui Tang University of Southern California - EE 202L - Class #1Slide #

3 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 Lecture Slides Supplementary Notes and Handouts SPICE Documentation University of Southern California - EE 202L - Class #1Slide #

4 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 #

5 Circuit Bootcamp 30 Analysis Problems in Sets of 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

6 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 #

7 Administrative Questions?

8 Electrical Engineering? Electrical Power Generate Distribute Condition Utilize Classical Focus Machinery Lighting Heating University of Southern California - EE 202L - Class #1Slide #

9 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 #

10 A Fundamental Discipline: Networks Communications Data Flows Web Linkages System Organizations Social Structures Distribution Strategies Linguistic Syntax Branch Node Electrical Networks? Network

11 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

12 Circuits Matter Not in Circuit Happy Bird High Voltage High Voltage Dead Bird

13 Nodes vs. Connections Connection Point Jump Node

14 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

15 Units and Magnitudes Currents Expressed in Amperes (Amps) - A 1 A = 1 coulomb / s = 6.25 x 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) = A 1 fa (femtoamp) = 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!

16 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

17 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

18 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

19 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

20 Exercise 2 Determine v 1,v 2,v 3 v v 2 Independent Voltage Source v 3

21 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

22 Resistor Structure Composition (old) Poor Tolerance High-Voltage Film Good Tolerance Good Tempco Wire-Wound High-Current Applications Bulky

23 Resistor Packages Axial Lead Surface Mount Arrays Potentiometers

24 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 #

25 Resistor Values E_ Standards Even Partitions of a Logarithmic Scale E24 for Lab Resistors Other Characterizations Power Rating Tempco (ppm/ o C)

26 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

27 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

28 Improper Source Combinations Current-Source Tie Set 1 3 Voltage-Source Loop Set 2 KCL Violated! 3 6 KVL Violated!

29 Branch Elements: Switches Open-Short Transitions, Loop Creators / Destroyers Mechanical Switches Electrical Switches Transistors

30 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

31 Exercise 3 (Design Problem) Determine v x 3 v 3 > 0 P 3 = 12 watts v x v 3 3 Mark up the Circuit Diagram!

32 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

33 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

34 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

35 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)