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EE11 FINAL
FALL 09
1
2
3
4
5
6
7
TOTAL
TOTAL
1.4
GRADE
Put your answers in the space provided
PROBLEM 1
Vo
Find Vo and Zo in the circuit of Fig.1.
20K
20K
+
20K
Zo
+
12V
6V
Vo = 6
FIG 1
Zo = 6.67K
R1
Vs
20K
Vs
Vo
Vo
R1
20K
FIG 3
FIG 2
Choose R1 in the circuit of
Fig.2 so that Vo/Vs = -5
Choose R1 in the circuit of
Fig.3 so that Vo/Vs = 5
R1 = 4K
R1 = 5K
10K
Choose R1 in the circuit of Fig.4 so that Vo/Vs = -50
20K
Vs
20K
Vo
R1
FIG 4
R1 = 870 ohms
PROBLEM 2
R1
Choose the resistors in Fig.1 so that
Vo = V1 + 3V2 - 4V3 - 2V4
One resistor is not needed. Set its value to .
R1 = 20K
R2 = 6.66K
R3 = 5K
R4 = 10K
R5 = 6.66K
R6 = 
R5
V1
R2
V2
-
Vo
R3
20K
R4
R6
V3
V4
FIG 1
Choose the resistors of the circuit so that
for Vs = 0V, Vo= -5 and for Vs=1, Vo=+5.
Vs
Vo
5V
R1
20K
R2
FIG 2
R1 = 20K
R2 = 2.5K
Choose the resistors of Fig.3 so that
For Vs = 1 + (0.2V/OF)T, Vo = -(1V/OF)T
One resistor is not needed. Set its value to .
5
V
R1
R2
Vo
R3
Vs
20K
R4
FIG 3
R1 = 20K
R2 = 4K
R3 = 4K
R4 = ∞
PROBLEM 3
3K
Determine the trip points for the circuit in Fig.1.
13K
Vs
13V
FIG 1
UTP = 3V
LTP = -3V
Determine the trip points for the circuit in Fig.2.
3K
13K
13V
Vs
FIG 2
UTP = 2.44V
LTP = -2.44V
1V
Determine the trip points for the circuit in Fig.3.
1K
13K
Vs
13V
3K
UTP = 0
LTP = -6V
FIG 3
Find the frequency of the multivibrator of Fig.4.
5K
13K
10K
±13V
FIG 4
fo = 65.4Hz
1uf
PROBLEM 4
FIG 1
A filter with the Bode plot of Fig.1 has the transfer function
H(jω) = K (1+jω/ω1)
(1+jω/ω2)
Find K, ω1, ω2.
K=1
ω1= 2
ω2 = 200
Find the differential equation that relates Vo to Vs for the filter
Vs
in Fig.2.
[ _0__
[ ___
(d2/dt2) + __1__ (d/dt) + __0__
10K
1uf 20K
Vo
] Vo =
(d2/dt2) + __-2__ (d/dt) + _-100__ ] Vs
FIG 2
H(s) = - (20K + 106/s)/10K
PROBLEM 5
6
15K
Vs
Vo
5
4
R1
V1
FIG 1
3
2
1
Choose R1 and V1 in the circuit of Fig.1 so
that for the input, shown as a broken line in
Fig.2, the output follows the solid line of the 0
figure. The diode drops a constant
0.6Vwhen it conducts.
t
time
FIG 2
V1 = 2.4V
R1 = 7.5K
Determine the gain of the amplifier in Fig.3 when the diode of the circuit is off.
∆Vo/∆Vs (Diode off) = 2
The diode on voltage is 0.6V. Determine Vo when the diode
begins to conduct.
Vo = Vs+0.6
Vo = 2Vs
V
Vo(Diode on.) = 1.2
Vs
Vo
20K
20K
20K
FIG 3
Determine the gain of the amplifier when the diode is
on.
ΔVo/ΔVs (Diode on) = 1.5V
Draw a Bridge rectifier in the block of Fog.4
FIG 4
PROBLEM 6
Vc
IC
N1:N2
RO
VB
120 rms
60Hz
IB
C
+
10V
Iz
10K
R1
-IE
IA
IL
Vo
FIG 1
In the power supply of Fig.1,
Vin = 170Cos(377t) VcMAX = 33V
Vo = 20V
IZ = 12ma.
<Vc> = 30V
IA = 1ma
The transistor beta = 100 and the VBE = 0.7V.
Find the transformer turns ratio
N1/N2 = 4.94 (or 4.7)
Find the value of Ro
Ro = 892 ohms
Find the value of R1
R1 = 10K
Find the current IC
IC = 114ma
Find the value of C
C = 158uf
Find the value of -IE
-IE = 101ma
Find the value of IB
IB = 1ma
Find the value of VB
VB = 20.7V
IL = 100ma
PROBLEM 7
+30V
In the circuit of Fig.1,Choose RE so that the
amplifier has an AC gain of -5.
R1
20K
IC
Vc
RE = 4K
Neglect the transistor base current and choose
VEQ so that the transistor is optimally biased
for sinusoidal operation. Take VBEQ as 0.6V
+
VsCos(t)
Vo
VB
VE
50K
RE
FIG 1
VEQ= 2.5V
VCQ = 17.5V
Find the D.C. collector voltage VCQ
Find the value of R1 for optimal sinusoidal operation.
R1 = 434K
Neglect base current and find the
transistor D.C. collector current ICQ.
ICQ = 0.625ma
Find the maximum value of Vs for which
the amplifier output is not distorted.
VsMAX = 2.5V
(or 5Vp-p)
Complete the truth table of Fig.3 for the MOS logic gate of
Fig.3. Take VDD as logical one and 0V as logical zero.
AB
00
01
11
10
CD
00
1
1
X
1
X=undefined
01
X
X
0
X
11
X
X
0
X
10
X
X
0
X
A
B
C
D
Z
C
D
Z
Write the logical expression for the circuit.
Z(A,B,C,D) = undefined. (Oops!)
VDD
A
B
FIG 2