EE 202L Class #3 - ee-classes2.usc.eduee-classes2.usc.edu/ee202/202-3.pdf · Assign Unity Value to Some Unknown Variable ... Model Statements (Not Needed for EE 202L) Commands.end

EE 202LClass #3

Last Time …

Series Resistance AddsShared CurrentOne Common Node,

Only Two Connections

Parallel Conductance AddsShared VoltageTwo Common Nodes

Req = R1 k R2 =R1R2

R1 +R2

Last Time …

Voltage Divider Current Divider

++

i

V

R

s

1

R2+v2

Rn

vx

= Vs

Rx

⌃Rix

= Is

Gx

⌃G

I s G2 nGG1

+

vi2

Review Problem

3

24 74

5

++

vx+

Determine vx

Linear Circuits (One Source)

Unit-Output MethodAssign Unity Value to Some Unknown VariableFind Consistent Source Value (Mark-Up Method)K = 1 / Source ValueOutput = K x Actual Source Value

++Vs

ii = K Vs +B

Linearity

0

Power Conserved !Linear Circuit

Unit-Output Method Example

1

Vs 12 2

3 5

++

1+

1/2

7/231/2109/4

7/2

447/4

31/4

1

12 12 2

3 5

++

vx+

K =4

109

vx

= 12K =48

109

++Vs I s

Linear Circuits (Multiple Sources)

Superposition MethodTurn Off All Sources Except OneFind ResponseRepeat For Each SourceAdd Results

i

Linear Circuit

i = K1 Vs +K2 Is

Linearity

Is = 0 ! i = K1 Vs

Vs = 0 ! i = K2 Is

++

Off

Short

Off

Open

Superposition Method Example

503010

5 15

15 ++

xi

Determine ix

iy = 151/15

1/15 + 1/10= 6

3010

5 15

15

R xiyi

Superposition Method Example

Voltage Source OffR = 5 + 30 k 15 = 15

ix

= 61/15

1/15 + 1/30= 4

503010

5 15

++

xi

�ix

=50

15 + 30 k 15= 2

Superposition Method Example

Current Source Off

ix

= 4 + (�2) = 2

Complete Response

43

2

2

++

2 ++

1

8 ++

6

+vx

Exercise 1

Determine vx

Equivalent Source Actions

++

R

Va

i

v

+

RV

Ra

i

v

+

v = Va � i R

v =

✓Va

R� i

◆R

= Va � i R

Source Substitutions

++

R

Va RV

Ra=

RIa ++

R

RIa=

Do Not Transform Dependent Sources

43

2

2

++

2 ++

1

8 ++

6

+vx

Source Substitution Example

18 32/3

Source Substitution Example

++

6

8 6 4/3

+-

43

2

2

++

2 ++

1

8 ++

6

+vx

++

612

4

+

+

Source Substitution Example

32/3 6 4/318 2

+vx

Put Everything Together

1/26+vx v

x

= 6⇥ 1

2= 3

33 4

6 ++

2

2

xi

Exercise 2

Determine ix

SPICE

Industry Standard Circuit Analysis ProgramUC Berkeley - 1973 (Fortran)PSpice, HSpice, TSpice, …

SPICE Input Options

Statement List Schematic Capture

General SPICE Format

* CommentNetlistModel Statements (Not Needed for EE 202L)Commands.end

43

2

2

++

2 ++

1

8 ++

6

+vx

SPICE Netlist - Assign Nodes

1 2

3

4

0

SPICE File: Netlist and Commands

V1 1 0 8R1 1 2 1R2 2 0 2V2 3 2 2R3 3 0 3I1 2 4 2R4 2 4 6V3 4 0 4

Commands

.dc V1 8 8 0.1 (sweep)

.print dc v(2)

Netlist