Post on 24-Feb-2018
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