# Exam-7 by shitingting

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```									Islamic University of Gaza                                         Eng.Monther Abu Sultan
Faculty of Engineering                                             Eng. Alaa Abu Auda
Electrical Engineering Dept.                                       Fall 2011

Time allowed: 2Hours                 Electronic I         Date:9/1/2012
Total mark: 50                        Final Exam          Closed Book Exam
Student Name:                                             Student #:
Problem #1:     15 point
1. For the following clipper circuit
Assume the input vin(t) varying form -20 ≤vin(t)≤ 20,D1,D2 are Si Diodes
a) [5pts]Sketch transfer curve?
b) [2pts]What the rang of vin(t) that make Vout(t)=       vin(t) ?
c) [3pts]Assume the triangular voltage is applied to the input of clipper, sketch Vout(t)

-12

D2
R1
Vout(t)
Vin(t)
2k
RL

1k
D1

-12
0

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2. For the following clamper circuit
The voltage signal vin(t) is applied to the input of clamper circuit
 [5pts]Sketch the voltage waveform Across the capacitor Vc?

10

D2

+Vc-
Vout(t)
Vin(t)
RL

D1   1k

-7
0

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Problem #2:      15 point
For following common emitter amplifier, the transistor β =50, VBE=0.7v.
a) [4pts]Determine the Q-point for BJT transistor?
b) [2pt ]Draw AC equivalent circuit using re model?
c) [2pts]Drive the input impedance Zin,output impedance Zout?
d) [3pts]Drive the voltage gain            ?
e) [2pts]Drive the total voltage gain
f) [2pts]Assume Vsig=0.3sin(wt) mvolt
i.  Sketch the total output voltage vout(t)
ii. Sketch the total collector voltage vc(t)

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Problem #3:      20 point
1. For the following combination network
a) [4pts]Determine the Dc voltages V1,V2?
b) [4pts]Determine the Q-point of each transistor?
c) [2pts]Sketch transfer curve for FET transistor?

+9v              +9v

2.2k             2k

Beta=100
V1
V2
IDss=8mA
Vp=-4v

10M                          0.5k
0.750k

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2. For the following Zener Diode circuit
The operating currents of the zener diodes Z1 is 30 mA(Vz=10v) ,Z2 is 15mA(Vz=5v)
a) [5pts]Determine the values of limiting resistance R1,R2?
b) [5pts]Determine the lowest value of Vsupply for which the current through 500Ω
is fixed ,when the operating current in Z1 is reduced to 5mA

R1                               R2

1k
25v                           Vz=10v                          Vz=5v       500
Z1                              Z2
Vsupply

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