Download 1) Equivalent impedances a. For the above circuit, determine the

Electric Circuits
ECSE 2010
Prof. Shayla Sawyer
HW04
Spring 2015
1) Equivalent impedances
C1
A
8E-9
a.
C2
6E-9
C5
6.5E-9
C3
6E-9
C4
3E-9
B
For the above circuit, determine the equivalent capacitance between A and B.
b.
L3
L1
A
1
2
1
20uH
2
10uH
2
2
L2
5uH
1
2
L4
15uH
1
L5
20uH
1
B
For the above circuit, determine the equivalent inductance between A and B.
1
Electric Circuits
ECSE 2010
c.
A
Prof. Shayla Sawyer
HW04
C6
Spring 2015
R2
L6
1
4E-9
2
10uH
2k
R1
1k
C7
3E-9
B
Find the equivalent impedance between node A and B. (Remember, ZR=R, ZL=sL, and ZC=1/sC).
2) Amplifier circuits
U1 7
3
Vin
0
L1
1
V+
OS2
+
2
OUT
2
-
OS1
V-
4
uA741
5
6
Vout
1
R
a. For the RL amplifier circuit, determine the relationship between Vout and Vin. As with RC amplifier
circuits, KCL is a good starting point. (The power is taken out for simplicity but the op amp is powered up).
b. What type of op amp is this?
2
Electric Circuits
ECSE 2010
Prof. Shayla Sawyer
HW04
U1 7
3
V1
V+
OS2
+
0
C1
1.59E-7
5
6
OUT
2
-
1
OS1
V-
4
uA741
Spring 2015
R5
2k
R2
4
R1
2
-
VOS1
1k
2k
OUT
R4
3
3k
+ 7
OS2
V+
U3
uA741
1
Vout
6
5
R6
6k
U2 7
3
V2
R3
+
0
OUT
2
2k
V+
OS2
-
4
uA741
OS1
V-
5
6
0
1
L1
1
2
1.27H
b. In the above circuit V1=V2=1sin(2π f t) where the frequency is 1 kHz. Determine Vout.
3
Electric Circuits
ECSE 2010
Prof. Shayla Sawyer
HW04
Spring 2015
3) Voltage/Current continuity
R1
R2
+ 2k -
+
+
-
V1
3k
+
C1
1E-9
-
2
L1
1E-6
1
In the above circuit, the voltage is defined as follows:
 5V
V1 = 
10V
t<0
0<t
(the voltage source turns on at t = 0)
a. Determine a mathematical expression for the source.
b. At t =0- (just before the voltage changes), for the polarities indicated, determine the voltage across each
component and the current through each component.
4
Electric Circuits
ECSE 2010
Prof. Shayla Sawyer
HW04
Spring 2015
b. At t=0+ (just after the voltage changes), determine the voltage across each component and the current
through each component for the polarities indicated in the circuit.
5
Electric Circuits
ECSE 2010
Prof. Shayla Sawyer
HW04
Spring 2015
4)
R1
10k
V1
C1
1E-9
a. Determine the voltage as a function of time for the source voltage V1 = 10 u(t).
b. Determine the voltage as a function of time for the source voltage
t<0
0

V 1 = 10 0 < t < 0.001
0
0.001 < t

[v]
6
Electric Circuits
ECSE 2010
Prof. Shayla Sawyer
HW04
5.
Spring 2015
R1
4k
R2
2k
V1
V
1n
1
R3
4k
TCLOSE = 3E-4
1
U2
2
2
10
TCLOSE = 1E-4
C3
2
1
U1
U3
TOPEN = 3E-4
R4
1k
0
In the above circuit, the voltage source turns on at t = 0. Switch U1 closes at t = 0.1 ms. Switch U2 closes
and switch U3 opens at t = 0.3 ms (effectively putting resistor R3 in series with C3 at t = 0.3 ms).
a. Determine the voltage across R3 as a function of time for t > 0.
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